From 991559357f6a03c3a5b70c053c8c2554aa8d5ee4 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@nicira.com>
Date: Wed, 25 Aug 2010 10:26:40 -0700
Subject: [PATCH] Implement initial Python bindings for Open vSwitch database.

These initial bindings pass a few hundred of the corresponding tests
for C implementations of various bits of the Open vSwitch library API.
The poorest part of them is actually the Python IDL interface in
ovs.db.idl, which has not received enough attention yet.  It appears
to work, but it doesn't yet support writes (transactions) and it is
difficult to use.  I hope to improve it as it becomes clear what
semantics Python applications actually want from an IDL.
---
 Makefile.am                    |   2 +-
 lib/automake.mk                |   3 +-
 ovsdb/OVSDB.py                 | 510 -----------------------------
 ovsdb/automake.mk              |   7 +-
 ovsdb/ovsdb-doc.in             |  27 +-
 ovsdb/ovsdb-dot.in             |   7 +-
 ovsdb/ovsdb-idlc.in            | 127 +++-----
 python/ovs/__init__.py         |   1 +
 python/ovs/automake.mk         |  42 +++
 python/ovs/daemon.py           | 431 +++++++++++++++++++++++++
 python/ovs/db/__init__.py      |   1 +
 python/ovs/db/data.py          | 433 +++++++++++++++++++++++++
 python/ovs/db/error.py         |  34 ++
 python/ovs/db/idl.py           | 305 ++++++++++++++++++
 python/ovs/db/parser.py        | 105 ++++++
 python/ovs/db/schema.py        | 159 ++++++++++
 python/ovs/db/types.py         | 545 +++++++++++++++++++++++++++++++
 python/ovs/dirs.py             |   7 +
 python/ovs/fatal_signal.py     | 121 +++++++
 python/ovs/json.py             | 528 +++++++++++++++++++++++++++++++
 python/ovs/jsonrpc.py          | 526 ++++++++++++++++++++++++++++++
 python/ovs/ovsuuid.py          |  72 +++++
 python/ovs/poller.py           | 123 +++++++
 python/ovs/process.py          |  39 +++
 python/ovs/reconnect.py        | 563 +++++++++++++++++++++++++++++++++
 python/ovs/socket_util.py      | 143 +++++++++
 python/ovs/stream.py           | 316 ++++++++++++++++++
 python/ovs/timeval.py          |  24 ++
 python/ovs/util.py             |  43 +++
 tests/atlocal.in               |   3 +
 tests/automake.mk              |  11 +
 tests/daemon-py.at             | 185 +++++++++++
 tests/daemon.at                |   2 +-
 tests/json.at                  |  45 ++-
 tests/jsonrpc-py.at            |  48 +++
 tests/jsonrpc.at               |   2 +-
 tests/ovsdb-column.at          |   6 +-
 tests/ovsdb-data.at            | 104 +++---
 tests/ovsdb-idl-py.at          | 149 +++++++++
 tests/ovsdb-schema.at          |   6 +-
 tests/ovsdb-table.at           |  14 +-
 tests/ovsdb-types.at           | 108 +++----
 tests/ovsdb.at                 |  57 ++++
 tests/reconnect.at             |  18 +-
 tests/test-daemon.py           |  66 ++++
 tests/test-json.py             |  92 ++++++
 tests/test-jsonrpc.c           |   2 +-
 tests/test-jsonrpc.py          | 221 +++++++++++++
 tests/test-ovsdb.py            | 372 ++++++++++++++++++++++
 tests/test-reconnect.py        | 195 ++++++++++++
 tests/testsuite.at             |   2 +
 xenserver/README               |   6 +
 xenserver/automake.mk          |   3 +-
 xenserver/openvswitch-xen.spec |  32 +-
 xenserver/uuid.py              | 541 +++++++++++++++++++++++++++++++
 55 files changed, 6776 insertions(+), 758 deletions(-)
 delete mode 100644 ovsdb/OVSDB.py
 create mode 100644 python/ovs/__init__.py
 create mode 100644 python/ovs/automake.mk
 create mode 100644 python/ovs/daemon.py
 create mode 100644 python/ovs/db/__init__.py
 create mode 100644 python/ovs/db/data.py
 create mode 100644 python/ovs/db/error.py
 create mode 100644 python/ovs/db/idl.py
 create mode 100644 python/ovs/db/parser.py
 create mode 100644 python/ovs/db/schema.py
 create mode 100644 python/ovs/db/types.py
 create mode 100644 python/ovs/dirs.py
 create mode 100644 python/ovs/fatal_signal.py
 create mode 100644 python/ovs/json.py
 create mode 100644 python/ovs/jsonrpc.py
 create mode 100644 python/ovs/ovsuuid.py
 create mode 100644 python/ovs/poller.py
 create mode 100644 python/ovs/process.py
 create mode 100644 python/ovs/reconnect.py
 create mode 100644 python/ovs/socket_util.py
 create mode 100644 python/ovs/stream.py
 create mode 100644 python/ovs/timeval.py
 create mode 100644 python/ovs/util.py
 create mode 100644 tests/daemon-py.at
 create mode 100644 tests/jsonrpc-py.at
 create mode 100644 tests/ovsdb-idl-py.at
 create mode 100644 tests/test-daemon.py
 create mode 100644 tests/test-json.py
 create mode 100644 tests/test-jsonrpc.py
 create mode 100644 tests/test-ovsdb.py
 create mode 100644 tests/test-reconnect.py
 create mode 100644 xenserver/uuid.py

diff --git a/Makefile.am b/Makefile.am
index eb7f4f78b..da4c1b334 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -130,4 +130,4 @@ include debian/automake.mk
 include vswitchd/automake.mk
 include ovsdb/automake.mk
 include xenserver/automake.mk
-
+include python/ovs/automake.mk
diff --git a/lib/automake.mk b/lib/automake.mk
index 801be72d6..efb84c5a0 100644
--- a/lib/automake.mk
+++ b/lib/automake.mk
@@ -234,7 +234,8 @@ lib/dirs.c: Makefile
 	 echo 'const char ovs_bindir[] = "$(bindir)";') > lib/dirs.c.tmp
 	mv lib/dirs.c.tmp lib/dirs.c
 
-install-data-local:
+install-data-local: lib-install-data-local
+lib-install-data-local:
 	$(MKDIR_P) $(DESTDIR)$(RUNDIR)
 	$(MKDIR_P) $(DESTDIR)$(PKIDIR)
 	$(MKDIR_P) $(DESTDIR)$(LOGDIR)
diff --git a/ovsdb/OVSDB.py b/ovsdb/OVSDB.py
deleted file mode 100644
index 3acc7b87a..000000000
--- a/ovsdb/OVSDB.py
+++ /dev/null
@@ -1,510 +0,0 @@
-import re
-
-class Error(Exception):
-    def __init__(self, msg):
-        Exception.__init__(self)
-        self.msg = msg
-
-def getMember(json, name, validTypes, description, default=None):
-    if name in json:
-        member = json[name]
-        if len(validTypes) and type(member) not in validTypes:
-            raise Error("%s: type mismatch for '%s' member"
-                        % (description, name))
-        return member
-    return default
-
-def mustGetMember(json, name, expectedType, description):
-    member = getMember(json, name, expectedType, description)
-    if member == None:
-        raise Error("%s: missing '%s' member" % (description, name))
-    return member
-
-class DbSchema:
-    def __init__(self, name, tables):
-        self.name = name
-        self.tables = tables
-
-    @staticmethod
-    def fromJson(json):
-        name = mustGetMember(json, 'name', [unicode], 'database')
-        tablesJson = mustGetMember(json, 'tables', [dict], 'database')
-        tables = {}
-        for tableName, tableJson in tablesJson.iteritems():
-            tables[tableName] = TableSchema.fromJson(tableJson,
-                                                     "%s table" % tableName)
-        return DbSchema(name, tables)
-
-class IdlSchema(DbSchema):
-    def __init__(self, name, tables, idlPrefix, idlHeader):
-        DbSchema.__init__(self, name, tables)
-        self.idlPrefix = idlPrefix
-        self.idlHeader = idlHeader
-
-    @staticmethod
-    def fromJson(json):
-        schema = DbSchema.fromJson(json)
-        idlPrefix = mustGetMember(json, 'idlPrefix', [unicode], 'database')
-        idlHeader = mustGetMember(json, 'idlHeader', [unicode], 'database')
-        return IdlSchema(schema.name, schema.tables, idlPrefix, idlHeader)
-
-class TableSchema:
-    def __init__(self, columns):
-        self.columns = columns
-
-    @staticmethod
-    def fromJson(json, description):
-        columnsJson = mustGetMember(json, 'columns', [dict], description)
-        columns = {}
-        for name, json in columnsJson.iteritems():
-            columns[name] = ColumnSchema.fromJson(
-                json, "column %s in %s" % (name, description))
-        return TableSchema(columns)
-
-class ColumnSchema:
-    def __init__(self, type, persistent):
-        self.type = type
-        self.persistent = persistent
-
-    @staticmethod
-    def fromJson(json, description):
-        type = Type.fromJson(mustGetMember(json, 'type', [dict, unicode],
-                                           description),
-                             'type of %s' % description)
-        ephemeral = getMember(json, 'ephemeral', [bool], description)
-        persistent = ephemeral != True
-        return ColumnSchema(type, persistent)
-
-def escapeCString(src):
-    dst = ""
-    for c in src:
-        if c in "\\\"":
-            dst += "\\" + c
-        elif ord(c) < 32:
-            if c == '\n':
-                dst += '\\n'
-            elif c == '\r':
-                dst += '\\r'
-            elif c == '\a':
-                dst += '\\a'
-            elif c == '\b':
-                dst += '\\b'
-            elif c == '\f':
-                dst += '\\f'
-            elif c == '\t':
-                dst += '\\t'
-            elif c == '\v':
-                dst += '\\v'
-            else:
-                dst += '\\%03o' % ord(c)
-        else:
-            dst += c
-    return dst
-
-def returnUnchanged(x):
-    return x
-
-class UUID:
-    x = "[0-9a-fA-f]"
-    uuidRE = re.compile("^(%s{8})-(%s{4})-(%s{4})-(%s{4})-(%s{4})(%s{8})$"
-                        % (x, x, x, x, x, x))
-
-    def __init__(self, value):
-        self.value = value
-
-    @staticmethod
-    def fromString(s):
-        if not uuidRE.match(s):
-            raise Error("%s is not a valid UUID" % s)
-        return UUID(s)
-
-    @staticmethod
-    def fromJson(json):
-        if UUID.isValidJson(json):
-            return UUID(json[1])
-        else:
-            raise Error("%s is not valid JSON for a UUID" % json)
-
-    @staticmethod
-    def isValidJson(json):
-        return len(json) == 2 and json[0] == "uuid" and uuidRE.match(json[1])
-            
-    def toJson(self):
-        return ["uuid", self.value]
-
-    def cInitUUID(self, var):
-        m = re.match(self.value)
-        return ["%s.parts[0] = 0x%s;" % (var, m.group(1)),
-                "%s.parts[1] = 0x%s%s;" % (var, m.group(2), m.group(3)),
-                "%s.parts[2] = 0x%s%s;" % (var, m.group(4), m.group(5)),
-                "%s.parts[3] = 0x%s;" % (var, m.group(6))]
-
-class Atom:
-    def __init__(self, type, value):
-        self.type = type
-        self.value = value
-
-    @staticmethod
-    def fromJson(type_, json):
-        if ((type_ == 'integer' and type(json) in [int, long])
-            or (type_ == 'real' and type(json) in [int, long, float])
-            or (type_ == 'boolean' and json in [True, False])
-            or (type_ == 'string' and type(json) in [str, unicode])):
-            return Atom(type_, json)
-        elif type_ == 'uuid':
-            return UUID.fromJson(json)
-        else:
-            raise Error("%s is not valid JSON for type %s" % (json, type_))
-
-    def toJson(self):
-        if self.type == 'uuid':
-            return self.value.toString()
-        else:
-            return self.value
-
-    def cInitAtom(self, var):
-        if self.type == 'integer':
-            return ['%s.integer = %d;' % (var, self.value)]
-        elif self.type == 'real':
-            return ['%s.real = %.15g;' % (var, self.value)]
-        elif self.type == 'boolean':
-            if self.value:
-                return ['%s.boolean = true;']
-            else:
-                return ['%s.boolean = false;']
-        elif self.type == 'string':
-            return ['%s.string = xstrdup("%s");'
-                    % (var, escapeCString(self.value))]
-        elif self.type == 'uuid':
-            return self.value.cInitUUID(var)
-
-    def toEnglish(self, escapeLiteral=returnUnchanged):
-        if self.type == 'integer':
-            return '%d' % self.value
-        elif self.type == 'real':
-            return '%.15g' % self.value
-        elif self.type == 'boolean':
-            if self.value:
-                return 'true'
-            else:
-                return 'false'
-        elif self.type == 'string':
-            return escapeLiteral(self.value)
-        elif self.type == 'uuid':
-            return self.value.value
-
-# Returns integer x formatted in decimal with thousands set off by commas.
-def commafy(x):
-    return _commafy("%d" % x)
-def _commafy(s):
-    if s.startswith('-'):
-        return '-' + _commafy(s[1:])
-    elif len(s) <= 3:
-        return s
-    else:
-        return _commafy(s[:-3]) + ',' + _commafy(s[-3:])
-
-class BaseType:
-    def __init__(self, type,
-                 enum=None,
-                 refTable=None, refType="strong",
-                 minInteger=None, maxInteger=None,
-                 minReal=None, maxReal=None,
-                 minLength=None, maxLength=None):
-        self.type = type
-        self.enum = enum
-        self.refTable = refTable
-        self.refType = refType
-        self.minInteger = minInteger
-        self.maxInteger = maxInteger
-        self.minReal = minReal
-        self.maxReal = maxReal
-        self.minLength = minLength
-        self.maxLength = maxLength
-
-    @staticmethod
-    def fromJson(json, description):
-        if type(json) == unicode:
-            return BaseType(json)
-        else:
-            atomicType = mustGetMember(json, 'type', [unicode], description)
-            enum = getMember(json, 'enum', [], description)
-            if enum:
-                enumType = Type(atomicType, None, 0, 'unlimited')
-                enum = Datum.fromJson(enumType, enum)
-            refTable = getMember(json, 'refTable', [unicode], description)
-            refType = getMember(json, 'refType', [unicode], description)
-            if refType == None:
-                refType = "strong"
-            minInteger = getMember(json, 'minInteger', [int, long], description)
-            maxInteger = getMember(json, 'maxInteger', [int, long], description)
-            minReal = getMember(json, 'minReal', [int, long, float], description)
-            maxReal = getMember(json, 'maxReal', [int, long, float], description)
-            minLength = getMember(json, 'minLength', [int], description)
-            maxLength = getMember(json, 'minLength', [int], description)
-            return BaseType(atomicType, enum, refTable, refType, minInteger, maxInteger, minReal, maxReal, minLength, maxLength)
-
-    def toEnglish(self, escapeLiteral=returnUnchanged):
-        if self.type == 'uuid' and self.refTable:
-            s = escapeLiteral(self.refTable)
-            if self.refType == 'weak':
-                s = "weak reference to " + s
-            return s
-        else:
-            return self.type
-
-    def constraintsToEnglish(self, escapeLiteral=returnUnchanged):
-        if self.enum:
-            literals = [value.toEnglish(escapeLiteral)
-                        for value in self.enum.values]
-            if len(literals) == 2:
-                return 'either %s or %s' % (literals[0], literals[1])
-            else:
-                return 'one of %s, %s, or %s' % (literals[0],
-                                                 ', '.join(literals[1:-1]),
-                                                 literals[-1])
-        elif self.minInteger != None and self.maxInteger != None:
-            return 'in range %s to %s' % (commafy(self.minInteger),
-                                         commafy(self.maxInteger))
-        elif self.minInteger != None:
-            return 'at least %s' % commafy(self.minInteger)
-        elif self.maxInteger != None:
-            return 'at most %s' % commafy(self.maxInteger)
-        elif self.minReal != None and self.maxReal != None:
-            return 'in range %g to %g' % (self.minReal, self.maxReal)
-        elif self.minReal != None:
-            return 'at least %g' % self.minReal
-        elif self.maxReal != None:
-            return 'at most %g' % self.maxReal
-        elif self.minLength != None and self.maxLength != None:
-            if self.minLength == self.maxLength:
-                return 'exactly %d characters long' % (self.minLength)
-            else:
-                return 'between %d and %d characters long' % (self.minLength, self.maxLength)
-        elif self.minLength != None:
-            return 'at least %d characters long' % self.minLength
-        elif self.maxLength != None:
-            return 'at most %d characters long' % self.maxLength
-        else:
-            return ''
-
-    def toCType(self, prefix):
-        if self.refTable:
-            return "struct %s%s *" % (prefix, self.refTable.lower())
-        else:
-            return {'integer': 'int64_t ',
-                    'real': 'double ',
-                    'uuid': 'struct uuid ',
-                    'boolean': 'bool ',
-                    'string': 'char *'}[self.type]
-
-    def toAtomicType(self):
-        return "OVSDB_TYPE_%s" % self.type.upper()
-
-    def copyCValue(self, dst, src):
-        args = {'dst': dst, 'src': src}
-        if self.refTable:
-            return ("%(dst)s = %(src)s->header_.uuid;") % args
-        elif self.type == 'string':
-            return "%(dst)s = xstrdup(%(src)s);" % args
-        else:
-            return "%(dst)s = %(src)s;" % args
-
-    def initCDefault(self, var, isOptional):
-        if self.refTable:
-            return "%s = NULL;" % var
-        elif self.type == 'string' and not isOptional:
-            return "%s = \"\";" % var
-        else:
-            return {'integer': '%s = 0;',
-                    'real': '%s = 0.0;',
-                    'uuid': 'uuid_zero(&%s);',
-                    'boolean': '%s = false;',
-                    'string': '%s = NULL;'}[self.type] % var
-
-    def cInitBaseType(self, indent, var):
-        stmts = []
-        stmts.append('ovsdb_base_type_init(&%s, OVSDB_TYPE_%s);' % (
-                var, self.type.upper()),)
-        if self.enum:
-            stmts.append("%s.enum_ = xmalloc(sizeof *%s.enum_);"
-                         % (var, var))
-            stmts += self.enum.cInitDatum("%s.enum_" % var)
-        if self.type == 'integer':
-            if self.minInteger != None:
-                stmts.append('%s.u.integer.min = INT64_C(%d);' % (var, self.minInteger))
-            if self.maxInteger != None:
-                stmts.append('%s.u.integer.max = INT64_C(%d);' % (var, self.maxInteger))
-        elif self.type == 'real':
-            if self.minReal != None:
-                stmts.append('%s.u.real.min = %d;' % (var, self.minReal))
-            if self.maxReal != None:
-                stmts.append('%s.u.real.max = %d;' % (var, self.maxReal))
-        elif self.type == 'string':
-            if self.minLength != None:
-                stmts.append('%s.u.string.minLen = %d;' % (var, self.minLength))            
-            if self.maxLength != None:
-                stmts.append('%s.u.string.maxLen = %d;' % (var, self.maxLength))
-        elif self.type == 'uuid':
-            if self.refTable != None:
-                stmts.append('%s.u.uuid.refTableName = "%s";' % (var, escapeCString(self.refTable)))
-        return '\n'.join([indent + stmt for stmt in stmts])
-
-class Type:
-    def __init__(self, key, value=None, min=1, max=1):
-        self.key = key
-        self.value = value
-        self.min = min
-        self.max = max
-    
-    @staticmethod
-    def fromJson(json, description):
-        if type(json) == unicode:
-            return Type(BaseType(json))
-        else:
-            keyJson = mustGetMember(json, 'key', [dict, unicode], description)
-            key = BaseType.fromJson(keyJson, 'key in %s' % description)
-
-            valueJson = getMember(json, 'value', [dict, unicode], description)
-            if valueJson:
-                value = BaseType.fromJson(valueJson,
-                                          'value in %s' % description)
-            else:
-                value = None
-
-            min = getMember(json, 'min', [int], description, 1)
-            max = getMember(json, 'max', [int, unicode], description, 1)
-            return Type(key, value, min, max)
-
-    def isScalar(self):
-        return self.min == 1 and self.max == 1 and not self.value
-
-    def isOptional(self):
-        return self.min == 0 and self.max == 1
-
-    def isOptionalPointer(self):
-        return (self.min == 0 and self.max == 1 and not self.value
-                and (self.key.type == 'string' or self.key.refTable))
-
-    def toEnglish(self, escapeLiteral=returnUnchanged):
-        keyName = self.key.toEnglish(escapeLiteral)
-        if self.value:
-            valueName = self.value.toEnglish(escapeLiteral)
-
-        if self.isScalar():
-            return keyName
-        elif self.isOptional():
-            if self.value:
-                return "optional %s-%s pair" % (keyName, valueName)
-            else:
-                return "optional %s" % keyName
-        else:
-            if self.max == "unlimited":
-                if self.min:
-                    quantity = "%d or more " % self.min
-                else:
-                    quantity = ""
-            elif self.min:
-                quantity = "%d to %d " % (self.min, self.max)
-            else:
-                quantity = "up to %d " % self.max
-
-            if self.value:
-                return "map of %s%s-%s pairs" % (quantity, keyName, valueName)
-            else:
-                if keyName.endswith('s'):
-                    plural = keyName + "es"
-                else:
-                    plural = keyName + "s"
-                return "set of %s%s" % (quantity, plural)
-
-    def constraintsToEnglish(self, escapeLiteral=returnUnchanged):
-        s = ""
-
-        constraints = []
-        keyConstraints = self.key.constraintsToEnglish(escapeLiteral)
-        if keyConstraints:
-            if self.value:
-                constraints += ['key ' + keyConstraints]
-            else:
-                constraints += [keyConstraints]
-
-        if self.value:
-            valueConstraints = self.value.constraintsToEnglish(escapeLiteral)
-            if valueConstraints:
-                constraints += ['value ' + valueConstraints]
-
-        return ', '.join(constraints)
-                
-    def cDeclComment(self):
-        if self.min == 1 and self.max == 1 and self.key.type == "string":
-            return "\t/* Always nonnull. */"
-        else:
-            return ""
-
-    def cInitType(self, indent, var):
-        initKey = self.key.cInitBaseType(indent, "%s.key" % var)
-        if self.value:
-            initValue = self.value.cInitBaseType(indent, "%s.value" % var)
-        else:
-            initValue = ('%sovsdb_base_type_init(&%s.value, '
-                         'OVSDB_TYPE_VOID);' % (indent, var))
-        initMin = "%s%s.n_min = %s;" % (indent, var, self.min)
-        if self.max == "unlimited":
-            max = "UINT_MAX"
-        else:
-            max = self.max
-        initMax = "%s%s.n_max = %s;" % (indent, var, max)
-        return "\n".join((initKey, initValue, initMin, initMax))
-
-class Datum:
-    def __init__(self, type, values):
-        self.type = type
-        self.values = values
-
-    @staticmethod
-    def fromJson(type_, json):
-        if not type_.value:
-            if len(json) == 2 and json[0] == "set":
-                values = []
-                for atomJson in json[1]:
-                    values += [Atom.fromJson(type_.key, atomJson)]
-            else:
-                values = [Atom.fromJson(type_.key, json)]
-        else:
-            if len(json) != 2 or json[0] != "map":
-                raise Error("%s is not valid JSON for a map" % json)
-            values = []
-            for pairJson in json[1]:
-                values += [(Atom.fromJson(type_.key, pairJson[0]),
-                            Atom.fromJson(type_.value, pairJson[1]))]
-        return Datum(type_, values)
-
-    def cInitDatum(self, var):
-        if len(self.values) == 0:
-            return ["ovsdb_datum_init_empty(%s);" % var]
-
-        s = ["%s->n = %d;" % (var, len(self.values))]
-        s += ["%s->keys = xmalloc(%d * sizeof *%s->keys);"
-              % (var, len(self.values), var)]
-
-        for i in range(len(self.values)):
-            key = self.values[i]
-            if self.type.value:
-                key = key[0]
-            s += key.cInitAtom("%s->keys[%d]" % (var, i))
-        
-        if self.type.value:
-            s += ["%s->values = xmalloc(%d * sizeof *%s->values);"
-                  % (var, len(self.values), var)]
-            for i in range(len(self.values)):
-                value = self.values[i][1]
-                s += key.cInitAtom("%s->values[%d]" % (var, i))
-        else:
-            s += ["%s->values = NULL;" % var]
-
-        if len(self.values) > 1:
-            s += ["ovsdb_datum_sort_assert(%s, OVSDB_TYPE_%s);"
-                  % (var, self.type.key.upper())]
-
-        return s
diff --git a/ovsdb/automake.mk b/ovsdb/automake.mk
index 5745697ae..5b46e168e 100644
--- a/ovsdb/automake.mk
+++ b/ovsdb/automake.mk
@@ -60,7 +60,6 @@ EXTRA_DIST += ovsdb/ovsdb-server.1.in
 
 # ovsdb-idlc
 EXTRA_DIST += \
-	ovsdb/OVSDB.py \
 	ovsdb/SPECS \
 	ovsdb/simplejson/__init__.py \
 	ovsdb/simplejson/_speedups.c				\
@@ -90,7 +89,7 @@ EXTRA_DIST += \
 	ovsdb/ovsdb-idlc.1
 DISTCLEANFILES += ovsdb/ovsdb-idlc
 SUFFIXES += .ovsidl
-OVSDB_IDLC = $(PYTHON) $(srcdir)/ovsdb/ovsdb-idlc.in
+OVSDB_IDLC = $(run_python) $(srcdir)/ovsdb/ovsdb-idlc.in
 .ovsidl.c:
 	$(OVSDB_IDLC) c-idl-source $< > $@.tmp
 	mv $@.tmp $@
@@ -115,12 +114,12 @@ $(OVSIDL_BUILT): ovsdb/ovsdb-idlc.in
 EXTRA_DIST += ovsdb/ovsdb-doc.in
 noinst_SCRIPTS += ovsdb/ovsdb-doc
 DISTCLEANFILES += ovsdb/ovsdb-doc
-OVSDB_DOC = $(PYTHON) $(srcdir)/ovsdb/ovsdb-doc.in
+OVSDB_DOC = $(run_python) $(srcdir)/ovsdb/ovsdb-doc.in
 
 # ovsdb-dot
 EXTRA_DIST += ovsdb/ovsdb-dot.in
 noinst_SCRIPTS += ovsdb/ovsdb-dot
 DISTCLEANFILES += ovsdb/ovsdb-dot
-OVSDB_DOT = $(PYTHON) $(srcdir)/ovsdb/ovsdb-dot.in
+OVSDB_DOT = $(run_python) $(srcdir)/ovsdb/ovsdb-dot.in
 
 include ovsdb/ovsdbmonitor/automake.mk
diff --git a/ovsdb/ovsdb-doc.in b/ovsdb/ovsdb-doc.in
index 4950e47e4..90de4521a 100755
--- a/ovsdb/ovsdb-doc.in
+++ b/ovsdb/ovsdb-doc.in
@@ -7,10 +7,9 @@ import re
 import sys
 import xml.dom.minidom
 
-sys.path.insert(0, "@abs_top_srcdir@/ovsdb")
-import simplejson as json
-
-from OVSDB import *
+import ovs.json
+from ovs.db import error
+import ovs.db.schema
 
 argv0 = sys.argv[0]
 
@@ -29,7 +28,7 @@ def textToNroff(s, font=r'\fR'):
         elif c == "'":
             return r'\(cq'
         else:
-            raise Error("bad escape")
+            raise error.Error("bad escape")
 
     # Escape - \ " ' as needed by nroff.
     s = re.sub('([-"\'\\\\])', escape, s)
@@ -58,7 +57,7 @@ def inlineXmlToNroff(node, font):
             elif node.hasAttribute('group'):
                 s += node.attributes['group'].nodeValue
             else:
-                raise Error("'ref' lacks column and table attributes")
+                raise error.Error("'ref' lacks column and table attributes")
             return s + font
         elif node.tagName == 'var':
             s = r'\fI'
@@ -66,9 +65,9 @@ def inlineXmlToNroff(node, font):
                 s += inlineXmlToNroff(child, r'\fI')
             return s + font
         else:
-            raise Error("element <%s> unknown or invalid here" % node.tagName)
+            raise error.Error("element <%s> unknown or invalid here" % node.tagName)
     else:
-        raise Error("unknown node %s in inline xml" % node)
+        raise error.Error("unknown node %s in inline xml" % node)
 
 def blockXmlToNroff(nodes, para='.PP'):
     s = ''
@@ -87,7 +86,7 @@ def blockXmlToNroff(nodes, para='.PP'):
                         s += ".IP \\(bu\n" + blockXmlToNroff(liNode.childNodes, ".IP")
                     elif (liNode.nodeType != node.TEXT_NODE
                           or not liNode.data.isspace()):
-                        raise Error("<ul> element may only have <li> children")
+                        raise error.Error("<ul> element may only have <li> children")
                 s += ".RE\n"
             elif node.tagName == 'dl':
                 if s != "":
@@ -109,7 +108,7 @@ def blockXmlToNroff(nodes, para='.PP'):
                         prev = 'dd'
                     elif (liNode.nodeType != node.TEXT_NODE
                           or not liNode.data.isspace()):
-                        raise Error("<dl> element may only have <dt> and <dd> children")
+                        raise error.Error("<dl> element may only have <dt> and <dd> children")
                     s += blockXmlToNroff(liNode.childNodes, ".IP")
                 s += ".RE\n"
             elif node.tagName == 'p':
@@ -121,7 +120,7 @@ def blockXmlToNroff(nodes, para='.PP'):
             else:
                 s += inlineXmlToNroff(node, r'\fR')
         else:
-            raise Error("unknown node %s in block xml" % node)
+            raise error.Error("unknown node %s in block xml" % node)
     if s != "" and not s.endswith('\n'):
         s += '\n'
     return s
@@ -165,7 +164,7 @@ def columnGroupToNroff(table, groupXml):
             body += '.ST "%s:"\n' % textToNroff(title)
             body += subIntro + subBody
         else:
-            raise Error("unknown element %s in <table>" % node.tagName)
+            raise error.Error("unknown element %s in <table>" % node.tagName)
     return summary, intro, body
 
 def tableSummaryToNroff(summary, level=0):
@@ -214,7 +213,7 @@ Column	Type
     return s
 
 def docsToNroff(schemaFile, xmlFile, erFile, title=None):
-    schema = DbSchema.fromJson(json.load(open(schemaFile, "r")))
+    schema = ovs.db.schema.DbSchema.from_json(ovs.json.from_file(schemaFile))
     doc = xml.dom.minidom.parse(xmlFile).documentElement
     
     schemaDate = os.stat(schemaFile).st_mtime
@@ -352,7 +351,7 @@ if __name__ == "__main__":
             if len(line):
                 print line
             
-    except Error, e:
+    except error.Error, e:
         sys.stderr.write("%s: %s\n" % (argv0, e.msg))
         sys.exit(1)
 
diff --git a/ovsdb/ovsdb-dot.in b/ovsdb/ovsdb-dot.in
index 179353035..3a9d9b0e8 100755
--- a/ovsdb/ovsdb-dot.in
+++ b/ovsdb/ovsdb-dot.in
@@ -6,11 +6,6 @@ import os
 import re
 import sys
 
-sys.path.insert(0, "@abs_top_srcdir@/ovsdb")
-import simplejson as json
-
-from OVSDB import *
-
 argv0 = sys.argv[0]
 
 def printEdge(tableName, baseType, label):
@@ -25,7 +20,7 @@ def printEdge(tableName, baseType, label):
             ', '.join(['%s=%s' % (k,v) for k,v in options.items()]))
 
 def schemaToDot(schemaFile):
-    schema = DbSchema.fromJson(json.load(open(schemaFile, "r")))
+    schema = DbSchema.fromJson(ovs.json.from_file(schemaFile))
 
     print "digraph %s {" % schema.name
     for tableName, table in schema.tables.iteritems():
diff --git a/ovsdb/ovsdb-idlc.in b/ovsdb/ovsdb-idlc.in
index 6c33f0784..e8371aa1d 100755
--- a/ovsdb/ovsdb-idlc.in
+++ b/ovsdb/ovsdb-idlc.in
@@ -5,72 +5,19 @@ import os
 import re
 import sys
 
-sys.path.insert(0, "@abs_top_srcdir@/ovsdb")
-import simplejson as json
-
-from OVSDB import *
+import ovs.json
+import ovs.db.error
+import ovs.db.schema
 
 argv0 = sys.argv[0]
 
-class Datum:
-    def __init__(self, type, values):
-        self.type = type
-        self.values = values
-
-    @staticmethod
-    def fromJson(type_, json):
-        if not type_.value:
-            if len(json) == 2 and json[0] == "set":
-                values = []
-                for atomJson in json[1]:
-                    values += [Atom.fromJson(type_.key, atomJson)]
-            else:
-                values = [Atom.fromJson(type_.key, json)]
-        else:
-            if len(json) != 2 or json[0] != "map":
-                raise Error("%s is not valid JSON for a map" % json)
-            values = []
-            for pairJson in json[1]:
-                values += [(Atom.fromJson(type_.key, pairJson[0]),
-                            Atom.fromJson(type_.value, pairJson[1]))]
-        return Datum(type_, values)
-
-    def cInitDatum(self, var):
-        if len(self.values) == 0:
-            return ["ovsdb_datum_init_empty(%s);" % var]
-
-        s = ["%s->n = %d;" % (var, len(self.values))]
-        s += ["%s->keys = xmalloc(%d * sizeof *%s->keys);"
-              % (var, len(self.values), var)]
-
-        for i in range(len(self.values)):
-            key = self.values[i]
-            if self.type.value:
-                key = key[0]
-            s += key.cInitAtom("%s->keys[%d]" % (var, i))
-        
-        if self.type.value:
-            s += ["%s->values = xmalloc(%d * sizeof *%s->values);"
-                  % (var, len(self.values), var)]
-            for i in range(len(self.values)):
-                value = self.values[i][1]
-                s += key.cInitAtom("%s->values[%d]" % (var, i))
-        else:
-            s += ["%s->values = NULL;" % var]
-
-        if len(self.values) > 1:
-            s += ["ovsdb_datum_sort_assert(%s, OVSDB_TYPE_%s);"
-                  % (var, self.type.key.upper())]
-
-        return s
-
 def parseSchema(filename):
-    return IdlSchema.fromJson(json.load(open(filename, "r")))
+    return ovs.db.schema.IdlSchema.from_json(ovs.json.from_file(filename))
 
 def annotateSchema(schemaFile, annotationFile):
-    schemaJson = json.load(open(schemaFile, "r"))
+    schemaJson = ovs.json.from_file(schemaFile)
     execfile(annotationFile, globals(), {"s": schemaJson})
-    json.dump(schemaJson, sys.stdout)
+    ovs.json.to_stream(schemaJson, sys.stdout)
 
 def constify(cType, const):
     if (const
@@ -82,12 +29,12 @@ def constify(cType, const):
 
 def cMembers(prefix, columnName, column, const):
     type = column.type
-    if type.min == 1 and type.max == 1:
+    if type.n_min == 1 and type.n_max == 1:
         singleton = True
         pointer = ''
     else:
         singleton = False
-        if type.isOptionalPointer():
+        if type.is_optional_pointer():
             pointer = ''
         else:
             pointer = '*'
@@ -106,7 +53,7 @@ def cMembers(prefix, columnName, column, const):
              'comment': type.cDeclComment()}
         members = [m]
 
-    if not singleton and not type.isOptionalPointer():
+    if not singleton and not type.is_optional_pointer():
         members.append({'name': 'n_%s' % columnName,
                         'type': 'size_t ',
                         'comment': ''})
@@ -270,28 +217,28 @@ static void
                 keyVar = "row->%s" % columnName
                 valueVar = None
 
-            if (type.min == 1 and type.max == 1) or type.isOptionalPointer():
+            if (type.n_min == 1 and type.n_max == 1) or type.is_optional_pointer():
                 print
                 print "    assert(inited);"
                 print "    if (datum->n >= 1) {"
-                if not type.key.refTable:
-                    print "        %s = datum->keys[0].%s;" % (keyVar, type.key.type)
+                if not type.key.ref_table:
+                    print "        %s = datum->keys[0].%s;" % (keyVar, type.key.type.to_string())
                 else:
-                    print "        %s = %s%s_cast(ovsdb_idl_get_row_arc(row_, &%stable_classes[%sTABLE_%s], &datum->keys[0].uuid));" % (keyVar, prefix, type.key.refTable.lower(), prefix, prefix.upper(), type.key.refTable.upper())
+                    print "        %s = %s%s_cast(ovsdb_idl_get_row_arc(row_, &%stable_classes[%sTABLE_%s], &datum->keys[0].uuid));" % (keyVar, prefix, type.key.ref_table.lower(), prefix, prefix.upper(), type.key.ref_table.upper())
 
                 if valueVar:
-                    if type.value.refTable:
-                        print "        %s = datum->values[0].%s;" % (valueVar, type.value.type)
+                    if type.value.ref_table:
+                        print "        %s = datum->values[0].%s;" % (valueVar, type.value.type.to_string())
                     else:
-                        print "        %s = %s%s_cast(ovsdb_idl_get_row_arc(row_, &%stable_classes[%sTABLE_%s], &datum->values[0].uuid));" % (valueVar, prefix, type.value.refTable.lower(), prefix, prefix.upper(), type.value.refTable.upper())
+                        print "        %s = %s%s_cast(ovsdb_idl_get_row_arc(row_, &%stable_classes[%sTABLE_%s], &datum->values[0].uuid));" % (valueVar, prefix, type.value.ref_table.lower(), prefix, prefix.upper(), type.value.ref_table.upper())
                 print "    } else {"
-                print "        %s" % type.key.initCDefault(keyVar, type.min == 0)
+                print "        %s" % type.key.initCDefault(keyVar, type.n_min == 0)
                 if valueVar:
-                    print "        %s" % type.value.initCDefault(valueVar, type.min == 0)
+                    print "        %s" % type.value.initCDefault(valueVar, type.n_min == 0)
                 print "    }"
             else:
-                if type.max != 'unlimited':
-                    print "    size_t n = MIN(%d, datum->n);" % type.max
+                if type.n_max != sys.maxint:
+                    print "    size_t n = MIN(%d, datum->n);" % type.n_max
                     nMax = "n"
                 else:
                     nMax = "datum->n"
@@ -304,18 +251,18 @@ static void
                 print "    row->n_%s = 0;" % columnName
                 print "    for (i = 0; i < %s; i++) {" % nMax
                 refs = []
-                if type.key.refTable:
-                    print "        struct %s%s *keyRow = %s%s_cast(ovsdb_idl_get_row_arc(row_, &%stable_classes[%sTABLE_%s], &datum->keys[i].uuid));" % (prefix, type.key.refTable.lower(), prefix, type.key.refTable.lower(), prefix, prefix.upper(), type.key.refTable.upper())
+                if type.key.ref_table:
+                    print "        struct %s%s *keyRow = %s%s_cast(ovsdb_idl_get_row_arc(row_, &%stable_classes[%sTABLE_%s], &datum->keys[i].uuid));" % (prefix, type.key.ref_table.lower(), prefix, type.key.ref_table.lower(), prefix, prefix.upper(), type.key.ref_table.upper())
                     keySrc = "keyRow"
                     refs.append('keyRow')
                 else:
-                    keySrc = "datum->keys[i].%s" % type.key.type
-                if type.value and type.value.refTable:
-                    print "        struct %s%s *valueRow = %s%s_cast(ovsdb_idl_get_row_arc(row_, &%stable_classes[%sTABLE_%s], &datum->values[i].uuid));" % (prefix, type.value.refTable.lower(), prefix, type.value.refTable.lower(), prefix, prefix.upper(), type.value.refTable.upper())
+                    keySrc = "datum->keys[i].%s" % type.key.type.to_string()
+                if type.value and type.value.ref_table:
+                    print "        struct %s%s *valueRow = %s%s_cast(ovsdb_idl_get_row_arc(row_, &%stable_classes[%sTABLE_%s], &datum->values[i].uuid));" % (prefix, type.value.ref_table.lower(), prefix, type.value.ref_table.lower(), prefix, prefix.upper(), type.value.ref_table.upper())
                     valueSrc = "valueRow"
                     refs.append('valueRow')
                 elif valueVar:
-                    valueSrc = "datum->values[i].%s" % type.value.type
+                    valueSrc = "datum->values[i].%s" % type.value.type.to_string()
                 if refs:
                     print "        if (%s) {" % ' && '.join(refs)
                     indent = "            "
@@ -338,7 +285,7 @@ static void
         # Unparse functions.
         for columnName, column in sorted(table.columns.iteritems()):
             type = column.type
-            if (type.min != 1 or type.max != 1) and not type.isOptionalPointer():
+            if (type.n_min != 1 or type.n_max != 1) and not type.is_optional_pointer():
                 print '''
 static void
 %(s)s_unparse_%(c)s(struct ovsdb_idl_row *row_)
@@ -467,24 +414,24 @@ const struct ovsdb_datum *
                  'args': ', '.join(['%(type)s%(name)s' % m for m in members])}
             print "{"
             print "    struct ovsdb_datum datum;"
-            if type.min == 1 and type.max == 1:
+            if type.n_min == 1 and type.n_max == 1:
                 print
                 print "    assert(inited);"
                 print "    datum.n = 1;"
                 print "    datum.keys = xmalloc(sizeof *datum.keys);"
-                print "    " + type.key.copyCValue("datum.keys[0].%s" % type.key.type, keyVar)
+                print "    " + type.key.copyCValue("datum.keys[0].%s" % type.key.type.to_string(), keyVar)
                 if type.value:
                     print "    datum.values = xmalloc(sizeof *datum.values);"
-                    print "    "+ type.value.copyCValue("datum.values[0].%s" % type.value.type, valueVar)
+                    print "    "+ type.value.copyCValue("datum.values[0].%s" % type.value.type.to_string(), valueVar)
                 else:
                     print "    datum.values = NULL;"
-            elif type.isOptionalPointer():
+            elif type.is_optional_pointer():
                 print
                 print "    assert(inited);"
                 print "    if (%s) {" % keyVar
                 print "        datum.n = 1;"
                 print "        datum.keys = xmalloc(sizeof *datum.keys);"
-                print "        " + type.key.copyCValue("datum.keys[0].%s" % type.key.type, keyVar)
+                print "        " + type.key.copyCValue("datum.keys[0].%s" % type.key.type.to_string(), keyVar)
                 print "    } else {"
                 print "        datum.n = 0;"
                 print "        datum.keys = NULL;"
@@ -501,9 +448,9 @@ const struct ovsdb_datum *
                 else:
                     print "    datum.values = NULL;"
                 print "    for (i = 0; i < %s; i++) {" % nVar
-                print "        " + type.key.copyCValue("datum.keys[i].%s" % type.key.type, "%s[i]" % keyVar)
+                print "        " + type.key.copyCValue("datum.keys[i].%s" % type.key.type.to_string(), "%s[i]" % keyVar)
                 if type.value:
-                    print "        " + type.value.copyCValue("datum.values[i].%s" % type.value.type, "%s[i]" % valueVar)
+                    print "        " + type.value.copyCValue("datum.values[i].%s" % type.value.type.to_string(), "%s[i]" % valueVar)
                 print "    }"
                 if type.value:
                     valueType = type.value.toAtomicType()
@@ -573,7 +520,7 @@ def ovsdb_escape(string):
     def escape(match):
         c = match.group(0)
         if c == '\0':
-            raise Error("strings may not contain null bytes")
+            raise ovs.db.error.Error("strings may not contain null bytes")
         elif c == '\\':
             return '\\\\'
         elif c == '\n':
@@ -654,8 +601,8 @@ if __name__ == "__main__":
             sys.exit(1)
 
         func(*args[1:])
-    except Error, e:
-        sys.stderr.write("%s: %s\n" % (argv0, e.msg))
+    except ovs.db.error.Error, e:
+        sys.stderr.write("%s: %s\n" % (argv0, e))
         sys.exit(1)
 
 # Local variables:
diff --git a/python/ovs/__init__.py b/python/ovs/__init__.py
new file mode 100644
index 000000000..218d8921e
--- /dev/null
+++ b/python/ovs/__init__.py
@@ -0,0 +1 @@
+# This file intentionally left blank.
diff --git a/python/ovs/automake.mk b/python/ovs/automake.mk
new file mode 100644
index 000000000..5c10c2a91
--- /dev/null
+++ b/python/ovs/automake.mk
@@ -0,0 +1,42 @@
+run_python = PYTHONPATH=$(top_srcdir)/python:$$PYTHON_PATH $(PYTHON)
+
+ovs_pyfiles = \
+	python/ovs/__init__.py \
+	python/ovs/daemon.py \
+	python/ovs/db/__init__.py \
+	python/ovs/db/data.py \
+	python/ovs/db/error.py \
+	python/ovs/db/idl.py \
+	python/ovs/db/parser.py \
+	python/ovs/db/schema.py \
+	python/ovs/db/types.py \
+	python/ovs/fatal_signal.py \
+	python/ovs/json.py \
+	python/ovs/jsonrpc.py \
+	python/ovs/ovsuuid.py \
+	python/ovs/poller.py \
+	python/ovs/process.py \
+	python/ovs/reconnect.py \
+	python/ovs/socket_util.py \
+	python/ovs/stream.py \
+	python/ovs/timeval.py \
+	python/ovs/util.py
+EXTRA_DIST += $(ovs_pyfiles) python/ovs/dirs.py
+
+if HAVE_PYTHON
+nobase_pkgdata_DATA = $(ovs_pyfiles)
+ovs-install-data-local:
+	$(MKDIR_P) python/ovs
+	(echo 'PKGDATADIR = """$(pkgdatadir)"""' && \
+	 echo 'RUNDIR = """@RUNDIR@"""' && \
+	 echo 'LOGDIR = """@LOGDIR@"""' && \
+	 echo 'BINDIR = """$(bindir)"""') > python/ovs/dirs.py.tmp
+	$(MKDIR_P) $(DESTDIR)$(pkgdatadir)/python/ovs
+	$(INSTALL_DATA) python/ovs/dirs.py.tmp $(DESTDIR)$(pkgdatadir)/python/ovs/dirs.py
+	rm python/ovs/dirs.py.tmp
+endif
+install-data-local: ovs-install-data-local
+
+uninstall-local: ovs-uninstall-local
+ovs-uninstall-local:
+	rm -f $(DESTDIR)$(pkgdatadir)/python/ovs/dirs.py
diff --git a/python/ovs/daemon.py b/python/ovs/daemon.py
new file mode 100644
index 000000000..a8373cfd0
--- /dev/null
+++ b/python/ovs/daemon.py
@@ -0,0 +1,431 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+import fcntl
+import logging
+import os
+import resource
+import signal
+import sys
+import time
+
+import ovs.dirs
+import ovs.fatal_signal
+#import ovs.lockfile
+import ovs.process
+import ovs.socket_util
+import ovs.timeval
+import ovs.util
+
+# --detach: Should we run in the background?
+_detach = False
+
+# --pidfile: Name of pidfile (null if none).
+_pidfile = None
+
+# --overwrite-pidfile: Create pidfile even if one already exists and is locked?
+_overwrite_pidfile = False
+
+# --no-chdir: Should we chdir to "/"?
+_chdir = True
+
+# --monitor: Should a supervisory process monitor the daemon and restart it if
+# it dies due to an error signal?
+_monitor = False
+
+# File descriptor used by daemonize_start() and daemonize_complete().
+_daemonize_fd = None
+
+def make_pidfile_name(name):
+    """Returns the file name that would be used for a pidfile if 'name' were
+    provided to set_pidfile()."""
+    if name is None or name == "":
+        return "%s/%s.pid" % (ovs.dirs.RUNDIR, ovs.util.PROGRAM_NAME)
+    else:
+        return ovs.util.abs_file_name(ovs.dirs.RUNDIR, name)
+
+def set_pidfile(name):
+    """Sets up a following call to daemonize() to create a pidfile named
+    'name'.  If 'name' begins with '/', then it is treated as an absolute path.
+    Otherwise, it is taken relative to ovs.util.RUNDIR, which is
+    $(prefix)/var/run by default.
+    
+    If 'name' is null, then ovs.util.PROGRAM_NAME followed by ".pid" is
+    used."""
+    global _pidfile
+    _pidfile = make_pidfile_name(name)
+
+def get_pidfile():
+    """Returns an absolute path to the configured pidfile, or None if no
+    pidfile is configured.  The caller must not modify or free the returned
+    string."""
+    return _pidfile
+
+def set_no_chdir():
+    """Sets that we do not chdir to "/"."""
+    global _chdir
+    _chdir = False
+
+def is_chdir_enabled():
+    """Will we chdir to "/" as part of daemonizing?"""
+    return _chdir
+
+def ignore_existing_pidfile():
+    """Normally, die_if_already_running() will terminate the program with a
+    message if a locked pidfile already exists.  If this function is called,
+    die_if_already_running() will merely log a warning."""
+    global _overwrite_pidfile
+    _overwrite_pidfile = True
+
+def set_detach():
+    """Sets up a following call to daemonize() to detach from the foreground
+    session, running this process in the background."""
+    global _detach
+    _detach = True
+
+def get_detach():
+    """Will daemonize() really detach?"""
+    return _detach
+
+def set_monitor():
+    """Sets up a following call to daemonize() to fork a supervisory process to
+    monitor the daemon and restart it if it dies due to an error signal."""
+    global _monitor
+    _monitor = True
+
+def _already_running():
+    """If a pidfile has been configured and that pidfile already exists and is
+    locked by a running process, returns True.  Otherwise, returns False."""
+    if _pidfile is not None:
+        try:
+            file = open(_pidfile, "r+")
+            try:
+                try:
+                    fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
+                except IOError, e:
+                    if e.errno in [errno.EACCES, errno.EAGAIN]:
+                        return True
+                    logging.error("error locking %s (%s)"
+                                  % (_pidfile, os.strerror(e.errno)))
+                    return False
+            finally:
+                # This releases the lock, which we don't really want.
+                file.close()
+        except IOError, e:
+            if e.errno == errno.ENOENT:
+                return False
+            logging.error("error opening %s (%s)"
+                          % (_pidfile, os.strerror(e.errno)))
+    return False
+
+def die_if_already_running():
+    """If a locked pidfile exists, issue a warning message and, unless
+    ignore_existing_pidfile() has been called, terminate the program."""
+    if _already_running():
+        if not _overwrite_pidfile:
+            sys.stderr.write("%s: already running\n" % get_pidfile())
+            sys.exit(1)
+        else:
+            logging.warn("%s: %s already running"
+                         % (get_pidfile(), ovs.util.PROGRAM_NAME))
+
+def _make_pidfile():
+    """If a pidfile has been configured, creates it and stores the running
+    process's pid in it.  Ensures that the pidfile will be deleted when the
+    process exits."""
+    if _pidfile is not None:
+        # Create pidfile via temporary file, so that observers never see an
+        # empty pidfile or an unlocked pidfile.
+        pid = os.getpid()
+        tmpfile = "%s.tmp%d" % (_pidfile, pid)
+        ovs.fatal_signal.add_file_to_unlink(tmpfile)
+
+        try:
+            # This is global to keep Python from garbage-collecting and
+            # therefore closing our file after this function exits.  That would
+            # unlock the lock for us, and we don't want that.
+            global file
+
+            file = open(tmpfile, "w")
+        except IOError, e:
+            logging.error("%s: create failed: %s"
+                          % (tmpfile, os.strerror(e.errno)))
+            return
+            
+        try:
+            fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
+        except IOError, e:
+            logging.error("%s: fcntl failed: %s"
+                          % (tmpfile, os.strerror(e.errno)))
+            file.close()
+            return
+
+        try:
+            file.write("%s\n" % pid)
+            file.flush()
+            ovs.fatal_signal.add_file_to_unlink(_pidfile)
+        except OSError, e:
+            logging.error("%s: write failed: %s"
+                          % (tmpfile, os.strerror(e.errno)))
+            file.close()
+            return
+            
+        try:
+            os.rename(tmpfile, _pidfile)
+        except OSError, e:
+            ovs.fatal_signal.remove_file_to_unlink(_pidfile)
+            logging.error("failed to rename \"%s\" to \"%s\": %s"
+                          % (tmpfile, _pidfile, os.strerror(e.errno)))
+            file.close()
+            return
+
+def daemonize():
+    """If configured with set_pidfile() or set_detach(), creates the pid file
+    and detaches from the foreground session."""
+    daemonize_start()
+    daemonize_complete()
+
+def _waitpid(pid, options):
+    while True:
+        try:
+            return os.waitpid(pid, options)
+        except OSError, e:
+            if e.errno == errno.EINTR:
+                pass
+            return -e.errno, 0
+
+def _fork_and_wait_for_startup():
+    try:
+        rfd, wfd = os.pipe()
+    except OSError, e:
+        sys.stderr.write("pipe failed: %s\n" % os.strerror(e.errno))
+        sys.exit(1)
+
+    try:
+        pid = os.fork()
+    except OSError, e:
+        sys.stderr.write("could not fork: %s\n" % os.strerror(e.errno))
+        sys.exit(1)
+
+    if pid > 0:
+        # Running in parent process.
+        os.close(wfd)
+        ovs.fatal_signal.fork()
+        try:
+            s = os.read(rfd, 1)
+        except OSError, e:
+            s = ""
+        if len(s) != 1:
+            retval, status = _waitpid(pid, 0)
+            if (retval == pid and
+                os.WIFEXITED(status) and os.WEXITSTATUS(status)):
+                # Child exited with an error.  Convey the same error to
+                # our parent process as a courtesy.
+                sys.exit(os.WEXITSTATUS(status))
+            else:
+                sys.stderr.write("fork child failed to signal startup\n")
+                sys.exit(1)
+
+        os.close(rfd)
+    else:
+        # Running in parent process.
+        os.close(rfd)
+        ovs.timeval.postfork()
+        #ovs.lockfile.postfork()
+
+        global _daemonize_fd
+        _daemonize_fd = wfd
+    return pid
+
+def _fork_notify_startup(fd):
+    if fd is not None:
+        error, bytes_written = ovs.socket_util.write_fully(fd, "0")
+        if error:
+            sys.stderr.write("could not write to pipe\n")
+            sys.exit(1)
+        os.close(fd)
+
+def _should_restart(status):
+    if os.WIFSIGNALED(status):
+        for signame in ("SIGABRT", "SIGALRM", "SIGBUS", "SIGFPE", "SIGILL",
+                        "SIGPIPE", "SIGSEGV", "SIGXCPU", "SIGXFSZ"):
+            if (signame in signal.__dict__ and
+                os.WTERMSIG(status) == signal.__dict__[signame]):
+                return True
+    return False
+
+def _monitor_daemon(daemon_pid):
+    # XXX should log daemon's stderr output at startup time
+    # XXX should use setproctitle module if available
+    last_restart = None
+    while True:
+        retval, status = _waitpid(daemon_pid, 0)
+        if retval < 0:
+            sys.stderr.write("waitpid failed\n")
+            sys.exit(1)
+        elif retval == daemon_pid:
+            status_msg = ("pid %d died, %s"
+                          % (daemon_pid, ovs.process.status_msg(status)))
+            
+            if _should_restart(status):
+                if os.WCOREDUMP(status):
+                    # Disable further core dumps to save disk space.
+                    try:
+                        resource.setrlimit(resource.RLIMIT_CORE, (0, 0))
+                    except resource.error:
+                        logging.warning("failed to disable core dumps")
+
+                # Throttle restarts to no more than once every 10 seconds.
+                if (last_restart is not None and
+                    ovs.timeval.msec() < last_restart + 10000):
+                    logging.warning("%s, waiting until 10 seconds since last "
+                                    "restart" % status_msg)
+                    while True:
+                        now = ovs.timeval.msec()
+                        wakeup = last_restart + 10000
+                        if now > wakeup:
+                            break
+                        print "sleep %f" % ((wakeup - now) / 1000.0)
+                        time.sleep((wakeup - now) / 1000.0)
+                last_restart = ovs.timeval.msec()
+
+                logging.error("%s, restarting" % status_msg)
+                daemon_pid = _fork_and_wait_for_startup()
+                if not daemon_pid:
+                    break
+            else:
+                logging.info("%s, exiting" % status_msg)
+                sys.exit(0)
+
+   # Running in new daemon process.
+
+def _close_standard_fds():
+    """Close stdin, stdout, stderr.  If we're started from e.g. an SSH session,
+    then this keeps us from holding that session open artificially."""
+    null_fd = ovs.socket_util.get_null_fd()
+    if null_fd >= 0:
+        os.dup2(null_fd, 0)
+        os.dup2(null_fd, 1)
+        os.dup2(null_fd, 2)
+
+def daemonize_start():
+    """If daemonization is configured, then starts daemonization, by forking
+    and returning in the child process.  The parent process hangs around until
+    the child lets it know either that it completed startup successfully (by
+    calling daemon_complete()) or that it failed to start up (by exiting with a
+    nonzero exit code)."""
+    
+    if _detach:
+        if _fork_and_wait_for_startup() > 0:
+            # Running in parent process.
+            sys.exit(0)
+        # Running in daemon or monitor process.
+
+    if _monitor:
+        saved_daemonize_fd = _daemonize_fd
+        daemon_pid = _fork_and_wait_for_startup()
+        if daemon_pid > 0:
+            # Running in monitor process.
+            _fork_notify_startup(saved_daemonize_fd)
+            _close_standard_fds()
+            _monitor_daemon(daemon_pid)
+        # Running in daemon process
+    
+    _make_pidfile()
+
+def daemonize_complete():
+    """If daemonization is configured, then this function notifies the parent
+    process that the child process has completed startup successfully."""
+    _fork_notify_startup(_daemonize_fd)
+
+    if _detach:
+        os.setsid()
+        if _chdir:
+            os.chdir("/")
+        _close_standard_fds()
+
+def usage():
+    sys.stdout.write("""
+Daemon options:
+   --detach                run in background as daemon
+   --no-chdir              do not chdir to '/'
+   --pidfile[=FILE]        create pidfile (default: %s/%s.pid)
+   --overwrite-pidfile     with --pidfile, start even if already running
+""" % (ovs.dirs.RUNDIR, ovs.util.PROGRAM_NAME))
+
+def read_pidfile(pidfile):
+    """Opens and reads a PID from 'pidfile'.  Returns the nonnegative PID if
+    successful, otherwise a negative errno value."""
+    try:
+        file = open(pidfile, "r")
+    except IOError, e:
+        logging.warning("%s: open: %s" % (pidfile, os.strerror(e.errno)))
+        return -e.errno
+
+    # Python fcntl doesn't directly support F_GETLK so we have to just try
+    # to lock it.  If we get a conflicting lock that's "success"; otherwise
+    # the file is not locked.
+    try:
+        fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
+        # File isn't locked if we get here, so treat that as an error.
+        logging.warning("%s: pid file is not locked" % pidfile)
+        try:
+            # As a side effect, this drops the lock.
+            file.close()
+        except IOError:
+            pass
+        return -errno.ESRCH
+    except IOError, e:
+        if e.errno not in [errno.EACCES, errno.EAGAIN]:
+            logging.warn("%s: fcntl: %s" % (pidfile, os.strerror(e.errno)))
+            return -e.errno
+
+    try:
+        try:
+            return int(file.readline())
+        except IOError, e:
+            logging.warning("%s: read: %s" % (pidfile, e.strerror))
+            return -e.errno
+        except ValueError:
+            logging.warning("%s does not contain a pid" % pidfile)
+            return -errno.EINVAL
+    finally:
+        try:
+            file.close()
+        except IOError:
+            pass
+
+# XXX Python's getopt does not support options with optional arguments, so we
+# have to separate --pidfile (with no argument) from --pidfile-name (with an
+# argument).  Need to write our own getopt I guess.
+LONG_OPTIONS = ["detach", "no-chdir", "pidfile", "pidfile-name=",
+                "overwrite-pidfile", "monitor"]
+
+def parse_opt(option, arg):
+    if option == '--detach':
+        set_detach()
+    elif option == '--no-chdir':
+        set_no_chdir()
+    elif option == '--pidfile':
+        set_pidfile(None)
+    elif option == '--pidfile-name':
+        set_pidfile(arg)
+    elif option == '--overwrite-pidfile':
+        ignore_existing_pidfile()
+    elif option == '--monitor':
+        set_monitor()
+    else:
+        return False
+    return True
diff --git a/python/ovs/db/__init__.py b/python/ovs/db/__init__.py
new file mode 100644
index 000000000..218d8921e
--- /dev/null
+++ b/python/ovs/db/__init__.py
@@ -0,0 +1 @@
+# This file intentionally left blank.
diff --git a/python/ovs/db/data.py b/python/ovs/db/data.py
new file mode 100644
index 000000000..bfdc11cbc
--- /dev/null
+++ b/python/ovs/db/data.py
@@ -0,0 +1,433 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+import logging
+import os
+import re
+import select
+import sys
+import uuid
+
+import ovs.poller
+import ovs.socket_util
+import ovs.json
+import ovs.jsonrpc
+import ovs.ovsuuid
+
+import ovs.db.parser
+from ovs.db import error
+import ovs.db.types
+
+class ConstraintViolation(error.Error):
+    def __init__(self, msg, json=None):
+        error.Error.__init__(self, msg, json, tag="constraint violation")
+
+def escapeCString(src):
+    dst = ""
+    for c in src:
+        if c in "\\\"":
+            dst += "\\" + c
+        elif ord(c) < 32:
+            if c == '\n':
+                dst += '\\n'
+            elif c == '\r':
+                dst += '\\r'
+            elif c == '\a':
+                dst += '\\a'
+            elif c == '\b':
+                dst += '\\b'
+            elif c == '\f':
+                dst += '\\f'
+            elif c == '\t':
+                dst += '\\t'
+            elif c == '\v':
+                dst += '\\v'
+            else:
+                dst += '\\%03o' % ord(c)
+        else:
+            dst += c
+    return dst
+
+def returnUnchanged(x):
+    return x
+
+class Atom(object):
+    def __init__(self, type, value=None):
+        self.type = type
+        if value is not None:
+            self.value = value
+        else:
+            self.value = type.default_atom()
+
+    def __cmp__(self, other):
+        if not isinstance(other, Atom) or self.type != other.type:
+            return NotImplemented
+        elif self.value < other.value:
+            return -1
+        elif self.value > other.value:
+            return 1
+        else:
+            return 0
+
+    def __hash__(self):
+        return hash(self.value)
+
+    @staticmethod
+    def default(type):
+        return Atom(type)
+
+    def is_default(self):
+        return self == default(self.type)
+
+    @staticmethod
+    def from_json(base, json, symtab=None):
+        type_ = base.type
+        json = ovs.db.parser.float_to_int(json)
+        if ((type_ == ovs.db.types.IntegerType and type(json) in [int, long])
+            or (type_ == ovs.db.types.RealType and type(json) in [int, long, float])
+            or (type_ == ovs.db.types.BooleanType and type(json) == bool)
+            or (type_ == ovs.db.types.StringType and type(json) in [str, unicode])):
+            atom = Atom(type_, json)
+        elif type_ == ovs.db.types.UuidType:
+            atom = Atom(type_, ovs.ovsuuid.UUID.from_json(json, symtab))
+        else:
+            raise error.Error("expected %s" % type_.to_string(), json)
+        atom.check_constraints(base)
+        return atom
+
+    def check_constraints(self, base):
+        """Checks whether 'atom' meets the constraints (if any) defined in
+        'base' and raises an ovs.db.error.Error if any constraint is violated.
+
+        'base' and 'atom' must have the same type.
+
+        Checking UUID constraints is deferred to transaction commit time, so
+        this function does nothing for UUID constraints."""
+        assert base.type == self.type
+        if base.enum is not None and self not in base.enum:
+            raise ConstraintViolation(
+                "%s is not one of the allowed values (%s)"
+                % (self.to_string(), base.enum.to_string()))
+        elif base.type in [ovs.db.types.IntegerType, ovs.db.types.RealType]:
+            if ((base.min is None or self.value >= base.min) and
+                (base.max is None or self.value <= base.max)):
+                pass
+            elif base.min is not None and base.max is not None:
+                raise ConstraintViolation(
+                    "%s is not in the valid range %.15g to %.15g (inclusive)"
+                    % (self.to_string(), base.min, base.max))
+            elif base.min is not None:
+                raise ConstraintViolation(
+                    "%s is less than minimum allowed value %.15g"
+                            % (self.to_string(), base.min))
+            else:
+                raise ConstraintViolation(
+                    "%s is greater than maximum allowed value %.15g"
+                    % (self.to_string(), base.max))
+        elif base.type == ovs.db.types.StringType:
+            # XXX The C version validates that the string is valid UTF-8 here.
+            # Do we need to do that in Python too?
+            s = self.value
+            length = len(s)
+            if length < base.min_length:
+                raise ConstraintViolation(
+                    "\"%s\" length %d is less than minimum allowed length %d"
+                    % (s, length, base.min_length))
+            elif length > base.max_length:
+                raise ConstraintViolation(
+                    "\"%s\" length %d is greater than maximum allowed "
+                    "length %d" % (s, length, base.max_length))
+    
+    def to_json(self):
+        if self.type == ovs.db.types.UuidType:
+            return self.value.to_json()
+        else:
+            return self.value
+
+    def cInitAtom(self, var):
+        if self.type == ovs.db.types.IntegerType:
+            return ['%s.integer = %d;' % (var, self.value)]
+        elif self.type == ovs.db.types.RealType:
+            return ['%s.real = %.15g;' % (var, self.value)]
+        elif self.type == ovs.db.types.BooleanType:
+            if self.value:
+                return ['%s.boolean = true;']
+            else:
+                return ['%s.boolean = false;']
+        elif self.type == ovs.db.types.StringType:
+            return ['%s.string = xstrdup("%s");'
+                    % (var, escapeCString(self.value))]
+        elif self.type == ovs.db.types.UuidType:
+            return self.value.cInitUUID(var)
+
+    def toEnglish(self, escapeLiteral=returnUnchanged):
+        if self.type == ovs.db.types.IntegerType:
+            return '%d' % self.value
+        elif self.type == ovs.db.types.RealType:
+            return '%.15g' % self.value
+        elif self.type == ovs.db.types.BooleanType:
+            if self.value:
+                return 'true'
+            else:
+                return 'false'
+        elif self.type == ovs.db.types.StringType:
+            return escapeLiteral(self.value)
+        elif self.type == ovs.db.types.UuidType:
+            return self.value.value
+
+    __need_quotes_re = re.compile("$|true|false|[^_a-zA-Z]|.*[^-._a-zA-Z]")
+    @staticmethod
+    def __string_needs_quotes(s):
+        return Atom.__need_quotes_re.match(s)
+
+    def to_string(self):
+        if self.type == ovs.db.types.IntegerType:
+            return '%d' % self.value
+        elif self.type == ovs.db.types.RealType:
+            return '%.15g' % self.value
+        elif self.type == ovs.db.types.BooleanType:
+            if self.value:
+                return 'true'
+            else:
+                return 'false'
+        elif self.type == ovs.db.types.StringType:
+            if Atom.__string_needs_quotes(self.value):
+                return ovs.json.to_string(self.value)
+            else:
+                return self.value
+        elif self.type == ovs.db.types.UuidType:
+            return str(self.value)
+
+    @staticmethod
+    def new(x):
+        if type(x) in [int, long]:
+            t = ovs.db.types.IntegerType
+        elif type(x) == float:
+            t = ovs.db.types.RealType
+        elif x in [False, True]:
+            t = ovs.db.types.RealType
+        elif type(x) in [str, unicode]:
+            t = ovs.db.types.StringType
+        elif isinstance(x, uuid):
+            t = ovs.db.types.UuidType
+        else:
+            raise TypeError
+        return Atom(t, x)
+
+class Datum(object):
+    def __init__(self, type, values={}):
+        self.type = type
+        self.values = values
+
+    def __cmp__(self, other):
+        if not isinstance(other, Datum):
+            return NotImplemented
+        elif self.values < other.values:
+            return -1
+        elif self.values > other.values:
+            return 1
+        else:
+            return 0
+
+    __hash__ = None
+
+    def __contains__(self, item):
+        return item in self.values
+
+    def clone(self):
+        return Datum(self.type, dict(self.values))
+
+    @staticmethod
+    def default(type):
+        if type.n_min == 0:
+            values = {}
+        elif type.is_map():
+            values = {type.key.default(): type.value.default()}
+        else:
+            values = {type.key.default(): None}
+        return Datum(type, values)
+
+    @staticmethod
+    def is_default(self):
+        return self == default(self.type)
+
+    def check_constraints(self):
+        """Checks that each of the atoms in 'datum' conforms to the constraints
+        specified by its 'type' and raises an ovs.db.error.Error.
+
+        This function is not commonly useful because the most ordinary way to
+        obtain a datum is ultimately via Datum.from_json() or Atom.from_json(),
+        which check constraints themselves."""
+        for keyAtom, valueAtom in self.values:
+            keyAtom.check_constraints()
+            if valueAtom is not None:
+                valueAtom.check_constraints()
+
+    @staticmethod
+    def from_json(type_, json, symtab=None):
+        """Parses 'json' as a datum of the type described by 'type'.  If
+        successful, returns a new datum.  On failure, raises an
+        ovs.db.error.Error.
+        
+        Violations of constraints expressed by 'type' are treated as errors.
+        
+        If 'symtab' is nonnull, then named UUIDs in 'symtab' are accepted.
+        Refer to ovsdb/SPECS for information about this, and for the syntax
+        that this function accepts."""
+        is_map = type_.is_map()
+        if (is_map or
+            (type(json) == list and len(json) > 0 and json[0] == "set")):
+            if is_map:
+                class_ = "map"
+            else:
+                class_ = "set"
+
+            inner = ovs.db.parser.unwrap_json(json, class_, list)
+            n = len(inner)
+            if n < type_.n_min or n > type_.n_max:
+                raise error.Error("%s must have %d to %d members but %d are "
+                                  "present" % (class_, type_.n_min,
+                                               type_.n_max, n),
+                                  json)
+
+            values = {}
+            for element in inner:
+                if is_map:
+                    key, value = ovs.db.parser.parse_json_pair(element)
+                    keyAtom = Atom.from_json(type_.key, key, symtab)
+                    valueAtom = Atom.from_json(type_.value, value, symtab)
+                else:
+                    keyAtom = Atom.from_json(type_.key, element, symtab)
+                    valueAtom = None
+
+                if keyAtom in values:
+                    if is_map:
+                        raise error.Error("map contains duplicate key")
+                    else:
+                        raise error.Error("set contains duplicate")
+
+                values[keyAtom] = valueAtom
+
+            return Datum(type_, values)
+        else:
+            keyAtom = Atom.from_json(type_.key, json, symtab)
+            return Datum(type_, {keyAtom: None})
+
+    def to_json(self):
+        if len(self.values) == 1 and not self.type.is_map():
+            key = self.values.keys()[0]
+            return key.to_json()
+        elif not self.type.is_map():
+            return ["set", [k.to_json() for k in sorted(self.values.keys())]]
+        else:
+            return ["map", [[k.to_json(), v.to_json()]
+                            for k, v in sorted(self.values.items())]]
+
+    def to_string(self):
+        if self.type.n_max > 1 or len(self.values) == 0:
+            if self.type.is_map():
+                s = "{"
+            else:
+                s = "["
+        else:
+            s = ""
+
+        i = 0
+        for key in sorted(self.values):
+            if i > 0:
+                s += ", "
+            i += 1
+
+            if self.type.is_map():
+                s += "%s=%s" % (key.to_string(), self.values[key].to_string())
+            else:
+                s += key.to_string()
+
+        if self.type.n_max > 1 or len(self.values) == 0:
+            if self.type.is_map():
+                s += "}"
+            else:
+                s += "]"
+        return s
+
+    def as_list(self):
+        if self.type.is_map():
+            return [[k.value, v.value] for k, v in self.values.iteritems()]
+        else:
+            return [k.value for k in self.values.iterkeys()]
+        
+    def as_scalar(self):
+        if len(self.values) == 1:
+            if self.type.is_map():
+                k, v = self.values.iteritems()[0]
+                return [k.value, v.value]
+            else:
+                return self.values.keys()[0].value
+        else:
+            return None
+
+    def __getitem__(self, key):
+        if not isinstance(key, Atom):
+            key = Atom.new(key)
+        if not self.type.is_map():
+            raise IndexError
+        elif key not in self.values:
+            raise KeyError
+        else:
+            return self.values[key].value
+
+    def get(self, key, default=None):
+        if not isinstance(key, Atom):
+            key = Atom.new(key)
+        if key in self.values:
+            return self.values[key].value
+        else:
+            return default
+        
+    def __str__(self):
+        return self.to_string()
+
+    def conforms_to_type(self):
+        n = len(self.values)
+        return n >= self.type.n_min and n <= self.type.n_max
+
+    def cInitDatum(self, var):
+        if len(self.values) == 0:
+            return ["ovsdb_datum_init_empty(%s);" % var]
+
+        s = ["%s->n = %d;" % (var, len(self.values))]
+        s += ["%s->keys = xmalloc(%d * sizeof *%s->keys);"
+              % (var, len(self.values), var)]
+
+        i = 0
+        for key, value in sorted(self.values.items()):
+            s += key.cInitAtom("%s->keys[%d]" % (var, i))
+            i += 1
+        
+        if self.type.value:
+            s += ["%s->values = xmalloc(%d * sizeof *%s->values);"
+                  % (var, len(self.values), var)]
+            i = 0
+            for key, value in sorted(self.values.items()):
+                s += value.cInitAtom("%s->values[%d]" % (var, i))
+                i += 1
+        else:
+            s += ["%s->values = NULL;" % var]
+
+        if len(self.values) > 1:
+            s += ["ovsdb_datum_sort_assert(%s, OVSDB_TYPE_%s);"
+                  % (var, self.type.key.type.to_string().upper())]
+
+        return s
diff --git a/python/ovs/db/error.py b/python/ovs/db/error.py
new file mode 100644
index 000000000..084db6e2e
--- /dev/null
+++ b/python/ovs/db/error.py
@@ -0,0 +1,34 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import ovs.json
+
+class Error(Exception):
+    def __init__(self, msg, json=None, tag=None):
+        Exception.__init__(self)
+        self.msg = msg
+        self.json = json
+        if tag is None:
+            if json is None:
+                self.tag = "ovsdb error"
+            else:
+                self.tag = "syntax error"
+        else:
+            self.tag = tag
+
+    def __str__(self):
+        syntax = ""
+        if self.json is not None:
+                syntax = "syntax \"%s\": " % ovs.json.to_string(self.json)
+        return "%s%s: %s" % (syntax, self.tag, self.msg)
diff --git a/python/ovs/db/idl.py b/python/ovs/db/idl.py
new file mode 100644
index 000000000..5260d983f
--- /dev/null
+++ b/python/ovs/db/idl.py
@@ -0,0 +1,305 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+
+import ovs.jsonrpc
+import ovs.db.schema
+from ovs.db import error
+import ovs.ovsuuid
+
+class Idl:
+    """Open vSwitch Database Interface Definition Language (OVSDB IDL).
+
+    The OVSDB IDL maintains an in-memory replica of a database.  It issues RPC
+    requests to an OVSDB database server and parses the responses, converting
+    raw JSON into data structures that are easier for clients to digest.
+
+    The IDL also assists with issuing database transactions.  The client
+    creates a transaction, manipulates the IDL data structures, and commits or
+    aborts the transaction.  The IDL then composes and issues the necessary
+    JSON-RPC requests and reports to the client whether the transaction
+    completed successfully.
+
+    If 'schema_cb' is provided, it should be a callback function that accepts
+    an ovs.db.schema.DbSchema as its argument.  It should determine whether the
+    schema is acceptable and raise an ovs.db.error.Error if it is not.  It may
+    also delete any tables or columns from the schema that the client has no
+    interest in monitoring, to save time and bandwidth during monitoring.  Its
+    return value is ignored."""
+
+    def __init__(self, remote, db_name, schema_cb=None):
+        """Creates and returns a connection to the database named 'db_name' on
+        'remote', which should be in a form acceptable to
+        ovs.jsonrpc.session.open().  The connection will maintain an in-memory
+        replica of the remote database."""
+        self.remote = remote
+        self.session = ovs.jsonrpc.Session.open(remote)
+        self.db_name = db_name
+        self.last_seqno = None
+        self.schema = None
+        self.state = None
+        self.change_seqno = 0
+        self.data = {}
+        self.schema_cb = schema_cb
+
+    def close(self):
+        self.session.close()
+
+    def run(self):
+        """Processes a batch of messages from the database server.  Returns
+        True if the database as seen through the IDL changed, False if it did
+        not change.  The initial fetch of the entire contents of the remote
+        database is considered to be one kind of change.
+
+        This function can return occasional false positives, that is, report
+        that the database changed even though it didn't.  This happens if the
+        connection to the database drops and reconnects, which causes the
+        database contents to be reloaded even if they didn't change.  (It could
+        also happen if the database server sends out a "change" that reflects
+        what we already thought was in the database, but the database server is
+        not supposed to do that.)
+
+        As an alternative to checking the return value, the client may check
+        for changes in the value returned by self.get_seqno()."""
+        initial_change_seqno = self.change_seqno
+        self.session.run()
+        if self.session.is_connected():
+            seqno = self.session.get_seqno()
+            if seqno != self.last_seqno:
+                self.last_seqno = seqno
+                self.state = (self.__send_schema_request, None)
+            if self.state:
+                self.state[0]()
+        return initial_change_seqno != self.change_seqno
+
+    def wait(self, poller):
+        """Arranges for poller.block() to wake up when self.run() has something
+        to do or when activity occurs on a transaction on 'self'."""
+        self.session.wait(poller)
+        if self.state and self.state[1]:
+            self.state[1](poller)
+
+    def get_seqno(self):
+        """Returns a number that represents the IDL's state.  When the IDL
+        updated (by self.run()), the return value changes."""
+        return self.change_seqno
+        
+    def __send_schema_request(self):
+        msg = ovs.jsonrpc.Message.create_request("get_schema", [self.db_name])
+        self.session.send(msg)
+        self.state = (lambda: self.__recv_schema(msg.id), self.__recv_wait)
+
+    def __recv_schema(self, id):
+        msg = self.session.recv()
+        if msg and msg.type == ovs.jsonrpc.Message.T_REPLY and msg.id == id:
+            try:
+                self.schema = ovs.db.schema.DbSchema.from_json(msg.result)
+            except error.Error, e:
+                logging.error("%s: parse error in received schema: %s"
+                              % (self.remote, e))
+                self.__error()
+                return
+
+            if self.schema_cb:
+                try:
+                    self.schema_cb(self.schema)
+                except error.Error, e:
+                    logging.error("%s: error validating schema: %s"
+                                  % (self.remote, e))
+                    self.__error()
+                    return
+
+            self.__send_monitor_request()
+        elif msg:
+            logging.error("%s: unexpected message expecting schema: %s"
+                          % (self.remote, msg))
+            self.__error()
+            
+    def __recv_wait(self, poller):
+        self.session.recv_wait(poller)
+
+    def __send_monitor_request(self):
+        monitor_requests = {}
+        for table in self.schema.tables.itervalues():
+            monitor_requests[table.name] = {"columns": table.columns.keys()}
+        msg = ovs.jsonrpc.Message.create_request(
+            "monitor", [self.db_name, None, monitor_requests])
+        self.session.send(msg)
+        self.state = (lambda: self.__recv_monitor_reply(msg.id),
+                      self.__recv_wait)
+
+    def __recv_monitor_reply(self, id):
+        msg = self.session.recv()
+        if msg and msg.type == ovs.jsonrpc.Message.T_REPLY and msg.id == id:
+            try:
+                self.change_seqno += 1
+                self.state = (self.__recv_update, self.__recv_wait)
+                self.__clear()
+                self.__parse_update(msg.result)
+            except error.Error, e:
+                logging.error("%s: parse error in received schema: %s"
+                              % (self.remote, e))
+                self.__error()
+        elif msg:
+            logging.error("%s: unexpected message expecting schema: %s"
+                          % (self.remote, msg))
+            self.__error()
+
+    def __recv_update(self):
+        msg = self.session.recv()
+        if (msg and msg.type == ovs.jsonrpc.Message.T_NOTIFY and
+            type(msg.params) == list and len(msg.params) == 2 and
+            msg.params[0] is None):
+            self.__parse_update(msg.params[1])
+        elif msg:
+            logging.error("%s: unexpected message expecting update: %s"
+                          % (self.remote, msg))
+            self.__error()
+
+    def __error(self):
+        self.session.force_reconnect()
+
+    def __parse_update(self, update):
+        try:
+            self.__do_parse_update(update)
+        except error.Error, e:
+            logging.error("%s: error parsing update: %s" % (self.remote, e))
+
+    def __do_parse_update(self, table_updates):
+        if type(table_updates) != dict:
+            raise error.Error("<table-updates> is not an object",
+                              table_updates)
+
+        for table_name, table_update in table_updates.iteritems():
+            table = self.schema.tables.get(table_name)
+            if not table:
+                raise error.Error("<table-updates> includes unknown "
+                                  "table \"%s\"" % table_name)
+
+            if type(table_update) != dict:
+                raise error.Error("<table-update> for table \"%s\" is not "
+                                  "an object" % table_name, table_update)
+
+            for uuid_string, row_update in table_update.iteritems():
+                if not ovs.ovsuuid.UUID.is_valid_string(uuid_string):
+                    raise error.Error("<table-update> for table \"%s\" "
+                                      "contains bad UUID \"%s\" as member "
+                                      "name" % (table_name, uuid_string),
+                                      table_update)
+                uuid = ovs.ovsuuid.UUID.from_string(uuid_string)
+
+                if type(row_update) != dict:
+                    raise error.Error("<table-update> for table \"%s\" "
+                                      "contains <row-update> for %s that "
+                                      "is not an object"
+                                      % (table_name, uuid_string))
+
+                old = row_update.get("old", None)
+                new = row_update.get("new", None)
+
+                if old is not None and type(old) != dict:
+                    raise error.Error("\"old\" <row> is not object", old)
+                if new is not None and type(new) != dict:
+                    raise error.Error("\"new\" <row> is not object", new)
+                if (old is not None) + (new is not None) != len(row_update):
+                    raise error.Error("<row-update> contains unexpected "
+                                      "member", row_update)
+                if not old and not new:
+                    raise error.Error("<row-update> missing \"old\" and "
+                                      "\"new\" members", row_update)
+
+                if self.__parse_row_update(table, uuid, old, new):
+                    self.change_seqno += 1
+
+    def __parse_row_update(self, table, uuid, old, new):
+        """Returns True if a column changed, False otherwise."""
+        row = self.data[table.name].get(uuid)
+        if not new:
+            # Delete row.
+            if row:
+                del self.data[table.name][uuid]
+            else:
+                # XXX rate-limit
+                logging.warning("cannot delete missing row %s from table %s"
+                                % (uuid, table.name))
+                return False
+        elif not old:
+            # Insert row.
+            if not row:
+                row = self.__create_row(table, uuid)
+            else:
+                # XXX rate-limit
+                logging.warning("cannot add existing row %s to table %s"
+                                % (uuid, table.name))
+            self.__modify_row(table, row, new)
+        else:
+            if not row:
+                row = self.__create_row(table, uuid)
+                # XXX rate-limit
+                logging.warning("cannot modify missing row %s in table %s"
+                                % (uuid, table_name))
+            self.__modify_row(table, row, new)
+        return True
+
+    def __modify_row(self, table, row, row_json):
+        changed = False
+        for column_name, datum_json in row_json.iteritems():
+            column = table.columns.get(column_name)
+            if not column:
+                # XXX rate-limit
+                logging.warning("unknown column %s updating table %s"
+                                % (column_name, table.name))
+                continue
+
+            try:
+                datum = ovs.db.data.Datum.from_json(column.type, datum_json)
+            except error.Error, e:
+                # XXX rate-limit
+                logging.warning("error parsing column %s in table %s: %s"
+                                % (column_name, table_name, e))
+                continue
+
+            if datum != row.__dict__[column_name]:
+                row.__dict__[column_name] = datum
+                changed = True
+            else:
+                # Didn't really change but the OVSDB monitor protocol always
+                # includes every value in a row.
+                pass
+        return changed
+
+    def __clear(self):
+        if self.data != {}:
+            for table_name in self.schema.tables:
+                if self.data[table_name] != {}:
+                    self.change_seqno += 1
+                    break
+
+        self.data = {}
+        for table_name in self.schema.tables:
+            self.data[table_name] = {}
+
+    def __create_row(self, table, uuid):
+        class Row(object):
+            pass
+        row = self.data[table.name][uuid] = Row()
+        for column in table.columns.itervalues():
+            row.__dict__[column.name] = ovs.db.data.Datum.default(column.type)
+        return row
+
+    def force_reconnect(self):
+        """Forces the IDL to drop its connection to the database and reconnect.
+        In the meantime, the contents of the IDL will not change."""
+        self.session.force_reconnect()
diff --git a/python/ovs/db/parser.py b/python/ovs/db/parser.py
new file mode 100644
index 000000000..07ce8e2b0
--- /dev/null
+++ b/python/ovs/db/parser.py
@@ -0,0 +1,105 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import re
+
+from ovs.db import error
+
+class Parser(object):
+    def __init__(self, json, name):
+        self.name = name
+        self.json = json
+        if type(json) != dict:
+            self.__raise_error("Object expected.")
+        self.used = set()
+
+    def __get(self, name, types, optional, default=None):
+        if name in self.json:
+            self.used.add(name)
+            member = float_to_int(self.json[name])
+            if is_identifier(member) and "id" in types:
+                return member
+            if len(types) and type(member) not in types:
+                self.__raise_error("Type mismatch for member '%s'." % name)
+            return member
+        else:
+            if not optional:        
+                self.__raise_error("Required '%s' member is missing." % name)
+            return default
+
+    def get(self, name, types):
+        return self.__get(name, types, False)
+
+    def get_optional(self, name, types, default=None):
+        return self.__get(name, types, True, default)
+
+    def __raise_error(self, message):
+        raise error.Error("Parsing %s failed: %s" % (self.name, message),
+                          self.json)
+
+    def finish(self):
+        missing = set(self.json) - set(self.used)
+        if missing:
+            name = missing.pop()
+            if len(missing) > 1:
+                self.__raise_error("Member '%s' and %d other members "
+                                   "are present but not allowed here"
+                                   % (name, len(missing)))
+            elif missing:
+                self.__raise_error("Member '%s' and 1 other member "
+                                   "are present but not allowed here" % name)
+            else:
+                self.__raise_error("Member '%s' is present but not "
+                                   "allowed here" % name)
+    
+def float_to_int(x):
+    # XXX still needed?
+    if type(x) == float:
+        integer = int(x)
+        if integer == x and integer >= -2**53 and integer < 2**53:
+            return integer
+    return x
+
+id_re = re.compile("[_a-zA-Z][_a-zA-Z0-9]*$")
+def is_identifier(s):
+    return type(s) in [str, unicode] and id_re.match(s)
+
+def json_type_to_string(type):
+    if type == None:
+        return "null"
+    elif type == bool:
+        return "boolean"
+    elif type == dict:
+        return "object"
+    elif type == list:
+        return "array"
+    elif type in [int, long, float]:
+        return "number"
+    elif type in [str, unicode]:
+        return "string"
+    else:
+        return "<invalid>"
+
+def unwrap_json(json, name, need_type):
+    if (type(json) != list or len(json) != 2 or json[0] != name or
+        type(json[1]) != need_type):
+        raise error.Error("expected [\"%s\", <%s>]"
+                          % (name, json_type_to_string(need_type)), json)
+    return json[1]
+
+def parse_json_pair(json):
+    if type(json) != list or len(json) != 2:
+        raise error.Error("expected 2-element array", json)
+    return json
+
diff --git a/python/ovs/db/schema.py b/python/ovs/db/schema.py
new file mode 100644
index 000000000..189b137c7
--- /dev/null
+++ b/python/ovs/db/schema.py
@@ -0,0 +1,159 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import sys
+
+from ovs.db import error
+import ovs.db.parser
+from ovs.db import types
+
+class DbSchema(object):
+    """Schema for an OVSDB database."""
+
+    def __init__(self, name, tables):
+        self.name = name
+        self.tables = tables
+
+        # Validate that all ref_tables refer to the names of tables
+        # that exist.
+        for table in self.tables.itervalues():
+            for column in table.columns.itervalues():
+                self.__check_ref_table(column, column.type.key, "key")
+                self.__check_ref_table(column, column.type.value, "value")
+
+    @staticmethod
+    def from_json(json):
+        parser = ovs.db.parser.Parser(json, "database schema")
+        name = parser.get("name", ['id'])
+        tablesJson = parser.get("tables", [dict])
+        parser.finish()
+
+        tables = {}
+        for tableName, tableJson in tablesJson.iteritems():
+            if tableName.startswith('_'):
+                raise error.Error("names beginning with \"_\" are reserved",
+                                  json)
+            elif not ovs.db.parser.is_identifier(tableName):
+                raise error.Error("name must be a valid id", json)
+            tables[tableName] = TableSchema.from_json(tableJson, tableName)
+
+        return DbSchema(name, tables)
+
+    def to_json(self):
+        tables = {}
+        for table in self.tables.itervalues():
+            tables[table.name] = table.to_json()
+        return {"name": self.name, "tables": tables}
+
+    def __check_ref_table(self, column, base, base_name):
+        if (base and base.type == types.UuidType and base.ref_table and
+            base.ref_table not in self.tables):
+            raise error.Error("column %s %s refers to undefined table %s"
+                              % (column.name, base_name, base.ref_table),
+                              tag="syntax error")
+
+class IdlSchema(DbSchema):
+    def __init__(self, name, tables, idlPrefix, idlHeader):
+        DbSchema.__init__(self, name, tables)
+        self.idlPrefix = idlPrefix
+        self.idlHeader = idlHeader
+
+    @staticmethod
+    def from_json(json):
+        parser = ovs.db.parser.Parser(json, "IDL schema")
+        idlPrefix = parser.get("idlPrefix", [unicode])
+        idlHeader = parser.get("idlHeader", [unicode])
+
+        subjson = dict(json)
+        del subjson["idlPrefix"]
+        del subjson["idlHeader"]
+        schema = DbSchema.from_json(subjson)
+
+        return IdlSchema(schema.name, schema.tables, idlPrefix, idlHeader)
+
+class TableSchema(object):
+    def __init__(self, name, columns, mutable=True, max_rows=sys.maxint):
+        self.name = name
+        self.columns = columns
+        self.mutable = mutable
+        self.max_rows = max_rows        
+
+    @staticmethod
+    def from_json(json, name):
+        parser = ovs.db.parser.Parser(json, "table schema for table %s" % name)
+        columnsJson = parser.get("columns", [dict])
+        mutable = parser.get_optional("mutable", [bool], True)
+        max_rows = parser.get_optional("maxRows", [int])
+        parser.finish()
+
+        if max_rows == None:
+            max_rows = sys.maxint
+        elif max_rows <= 0:
+            raise error.Error("maxRows must be at least 1", json)
+
+        if not columnsJson:
+            raise error.Error("table must have at least one column", json)
+
+        columns = {}
+        for columnName, columnJson in columnsJson.iteritems():
+            if columnName.startswith('_'):
+                raise error.Error("names beginning with \"_\" are reserved",
+                                  json)
+            elif not ovs.db.parser.is_identifier(columnName):
+                raise error.Error("name must be a valid id", json)
+            columns[columnName] = ColumnSchema.from_json(columnJson,
+                                                         columnName)
+
+        return TableSchema(name, columns, mutable, max_rows)
+
+    def to_json(self):
+        json = {}
+        if not self.mutable:
+            json["mutable"] = False
+
+        json["columns"] = columns = {}
+        for column in self.columns.itervalues():
+            if not column.name.startswith("_"):
+                columns[column.name] = column.to_json()
+
+        if self.max_rows != sys.maxint:
+            json["maxRows"] = self.max_rows
+
+        return json
+
+class ColumnSchema(object):
+    def __init__(self, name, mutable, persistent, type):
+        self.name = name
+        self.mutable = mutable
+        self.persistent = persistent
+        self.type = type
+
+    @staticmethod
+    def from_json(json, name):
+        parser = ovs.db.parser.Parser(json, "schema for column %s" % name)
+        mutable = parser.get_optional("mutable", [bool], True)
+        ephemeral = parser.get_optional("ephemeral", [bool], False)
+        type = types.Type.from_json(parser.get("type", [dict, unicode]))
+        parser.finish()
+
+        return ColumnSchema(name, mutable, not ephemeral, type)
+
+    def to_json(self):
+        json = {"type": self.type.to_json()}
+        if not self.mutable:
+            json["mutable"] = False
+        if not self.persistent:
+            json["ephemeral"] = True
+        return json
+
diff --git a/python/ovs/db/types.py b/python/ovs/db/types.py
new file mode 100644
index 000000000..aa0a8eda8
--- /dev/null
+++ b/python/ovs/db/types.py
@@ -0,0 +1,545 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import sys
+
+from ovs.db import error
+import ovs.db.parser
+import ovs.db.data
+import ovs.ovsuuid
+
+class AtomicType(object):
+    def __init__(self, name, default):
+        self.name = name
+        self.default = default
+
+    @staticmethod
+    def from_string(s):
+        if s != "void":
+            for atomic_type in ATOMIC_TYPES:
+                if s == atomic_type.name:
+                    return atomic_type
+        raise error.Error("\"%s\" is not an atomic type" % s)
+
+    @staticmethod
+    def from_json(json):
+        if type(json) not in [str, unicode]:
+            raise error.Error("atomic-type expected", json)
+        try:
+            return AtomicType.from_string(json)
+        except error.Error:
+            raise error.Error("\"%s\" is not an atomic-type" % json, json)
+
+    def __str__(self):
+        return self.name
+
+    def to_string(self):
+        return self.name
+
+    def to_json(self):
+        return self.name
+
+    def default_atom(self):
+        return ovs.db.data.Atom(self, self.default)
+
+VoidType = AtomicType("void", None)
+IntegerType = AtomicType("integer", 0)
+RealType = AtomicType("real", 0.0)
+BooleanType = AtomicType("boolean", False)
+StringType = AtomicType("string", "")
+UuidType = AtomicType("uuid", ovs.ovsuuid.UUID.zero())
+
+ATOMIC_TYPES = [VoidType, IntegerType, RealType, BooleanType, StringType,
+                UuidType]
+
+def escapeCString(src):
+    dst = ""
+    for c in src:
+        if c in "\\\"":
+            dst += "\\" + c
+        elif ord(c) < 32:
+            if c == '\n':
+                dst += '\\n'
+            elif c == '\r':
+                dst += '\\r'
+            elif c == '\a':
+                dst += '\\a'
+            elif c == '\b':
+                dst += '\\b'
+            elif c == '\f':
+                dst += '\\f'
+            elif c == '\t':
+                dst += '\\t'
+            elif c == '\v':
+                dst += '\\v'
+            else:
+                dst += '\\%03o' % ord(c)
+        else:
+            dst += c
+    return dst
+
+def commafy(x):
+    """Returns integer x formatted in decimal with thousands set off by
+    commas."""
+    return _commafy("%d" % x)
+def _commafy(s):
+    if s.startswith('-'):
+        return '-' + _commafy(s[1:])
+    elif len(s) <= 3:
+        return s
+    else:
+        return _commafy(s[:-3]) + ',' + _commafy(s[-3:])
+
+def returnUnchanged(x):
+    return x
+
+class BaseType(object):
+    def __init__(self, type_, enum=None, min=None, max=None,
+                 min_length = 0, max_length=sys.maxint, ref_table=None):
+        assert isinstance(type_, AtomicType)
+        self.type = type_
+        self.enum = enum
+        self.min = min
+        self.max = max
+        self.min_length = min_length
+        self.max_length = max_length
+        self.ref_table = ref_table
+
+    def default(self):
+        return ovs.db.data.Atom.default(self.type)
+
+    def __eq__(self, other):
+        if not isinstance(other, BaseType):
+            return NotImplemented
+        return (self.type == other.type and self.enum == other.enum and
+                self.min == other.min and self.max == other.max and
+                self.min_length == other.min_length and
+                self.max_length == other.max_length and
+                self.ref_table == other.ref_table)
+
+    def __ne__(self, other):
+        if not isinstance(other, BaseType):
+            return NotImplemented
+        else:
+            return not (self == other)
+
+    @staticmethod
+    def __parse_uint(parser, name, default):
+        value = parser.get_optional(name, [int, long])
+        if value is None:
+            value = default
+        else:
+            max_value = 2**32 - 1
+            if value < 0 or value > max_value:
+                raise error.Error("%s out of valid range 0 to %d"
+                                  % (name, max_value), value)
+        return value
+
+    @staticmethod
+    def from_json(json):
+        if type(json) == unicode:
+            return BaseType(AtomicType.from_json(json))
+
+        parser = ovs.db.parser.Parser(json, "ovsdb type")
+        atomic_type = AtomicType.from_json(parser.get("type", [str, unicode]))
+
+        base = BaseType(atomic_type)
+
+        enum = parser.get_optional("enum", [])
+        if enum is not None:
+            base.enum = ovs.db.data.Datum.from_json(BaseType.get_enum_type(base.type), enum)
+        elif base.type == IntegerType:
+            base.min = parser.get_optional("minInteger", [int, long])
+            base.max = parser.get_optional("maxInteger", [int, long])
+            if base.min is not None and base.max is not None and base.min > base.max:
+                raise error.Error("minInteger exceeds maxInteger", json)
+        elif base.type == RealType:
+            base.min = parser.get_optional("minReal", [int, long, float])
+            base.max = parser.get_optional("maxReal", [int, long, float])
+            if base.min is not None and base.max is not None and base.min > base.max:
+                raise error.Error("minReal exceeds maxReal", json)
+        elif base.type == StringType:
+            base.min_length = BaseType.__parse_uint(parser, "minLength", 0)
+            base.max_length = BaseType.__parse_uint(parser, "maxLength",
+                                                    sys.maxint)
+            if base.min_length > base.max_length:
+                raise error.Error("minLength exceeds maxLength", json)
+        elif base.type == UuidType:
+            base.ref_table = parser.get_optional("refTable", ['id'])
+            if base.ref_table:
+                base.ref_type = parser.get_optional("refType", [str, unicode],
+                                                   "strong")
+                if base.ref_type not in ['strong', 'weak']:
+                    raise error.Error("refType must be \"strong\" or \"weak\" "
+                                      "(not \"%s\")" % base.ref_type)
+        parser.finish()
+
+        return base
+
+    def to_json(self):
+        if not self.has_constraints():
+            return self.type.to_json()
+
+        json = {'type': self.type.to_json()}
+
+        if self.enum:
+            json['enum'] = self.enum.to_json()
+
+        if self.type == IntegerType:
+            if self.min is not None:
+                json['minInteger'] = self.min
+            if self.max is not None:
+                json['maxInteger'] = self.max
+        elif self.type == RealType:
+            if self.min is not None:
+                json['minReal'] = self.min
+            if self.max is not None:
+                json['maxReal'] = self.max
+        elif self.type == StringType:
+            if self.min_length != 0:
+                json['minLength'] = self.min_length
+            if self.max_length != sys.maxint:
+                json['maxLength'] = self.max_length
+        elif self.type == UuidType:
+            if self.ref_table:
+                json['refTable'] = self.ref_table
+                if self.ref_type != 'strong':
+                    json['refType'] = self.ref_type
+        return json
+
+    def clone(self):
+        return BaseType(self.type, self.enum.clone(), self.min, self.max,
+                        self.min_length, self.max_length, self.ref_table)
+
+    def is_valid(self):
+        if self.type in (VoidType, BooleanType, UuidType):
+            return True
+        elif self.type in (IntegerType, RealType):
+            return self.min is None or self.max is None or self.min <= self.max
+        elif self.type == StringType:
+            return self.min_length <= self.max_length
+        else:
+            return False
+
+    def has_constraints(self):
+        return (self.enum is not None or self.min is not None or self.max is not None or
+                self.min_length != 0 or self.max_length != sys.maxint or
+                self.ref_table is not None)
+
+    def without_constraints(self):
+        return BaseType(self.type)
+
+    @staticmethod
+    def get_enum_type(atomic_type):
+        """Returns the type of the 'enum' member for a BaseType whose
+        'type' is 'atomic_type'."""
+        return Type(BaseType(atomic_type), None, 1, sys.maxint)
+    
+    def is_ref(self):
+        return self.type == UuidType and self.ref_table is not None
+
+    def is_strong_ref(self):
+        return self.is_ref() and self.ref_type == 'strong'
+
+    def is_weak_ref(self):
+        return self.is_ref() and self.ref_type == 'weak'
+
+    def toEnglish(self, escapeLiteral=returnUnchanged):
+        if self.type == UuidType and self.ref_table:
+            s = escapeLiteral(self.ref_table)
+            if self.ref_type == 'weak':
+                s = "weak reference to " + s
+            return s
+        else:
+            return self.type.to_string()
+
+    def constraintsToEnglish(self, escapeLiteral=returnUnchanged):
+        if self.enum:
+            literals = [value.toEnglish(escapeLiteral)
+                        for value in self.enum.values]
+            if len(literals) == 2:
+                return 'either %s or %s' % (literals[0], literals[1])
+            else:
+                return 'one of %s, %s, or %s' % (literals[0],
+                                                 ', '.join(literals[1:-1]),
+                                                 literals[-1])
+        elif self.min is not None and self.max is not None:
+            if self.type == IntegerType:
+                return 'in range %s to %s' % (commafy(self.min),
+                                              commafy(self.max))
+            else:
+                return 'in range %g to %g' % (self.min, self.max)
+        elif self.min is not None:
+            if self.type == IntegerType:
+                return 'at least %s' % commafy(self.min)
+            else:
+                return 'at least %g' % self.min
+        elif self.max is not None:
+            if self.type == IntegerType:
+                return 'at most %s' % commafy(self.max)
+            else:
+                return 'at most %g' % self.max
+        elif self.min_length is not None and self.max_length is not None:
+            if self.min_length == self.max_length:
+                return 'exactly %d characters long' % (self.min_length)
+            else:
+                return 'between %d and %d characters long' % (self.min_length, self.max_length)
+        elif self.min_length is not None:
+            return 'at least %d characters long' % self.min_length
+        elif self.max_length is not None:
+            return 'at most %d characters long' % self.max_length
+        else:
+            return ''
+
+    def toCType(self, prefix):
+        if self.ref_table:
+            return "struct %s%s *" % (prefix, self.ref_table.lower())
+        else:
+            return {IntegerType: 'int64_t ',
+                    RealType: 'double ',
+                    UuidType: 'struct uuid ',
+                    BooleanType: 'bool ',
+                    StringType: 'char *'}[self.type]
+
+    def toAtomicType(self):
+        return "OVSDB_TYPE_%s" % self.type.to_string().upper()
+
+    def copyCValue(self, dst, src):
+        args = {'dst': dst, 'src': src}
+        if self.ref_table:
+            return ("%(dst)s = %(src)s->header_.uuid;") % args
+        elif self.type == StringType:
+            return "%(dst)s = xstrdup(%(src)s);" % args
+        else:
+            return "%(dst)s = %(src)s;" % args
+
+    def initCDefault(self, var, is_optional):
+        if self.ref_table:
+            return "%s = NULL;" % var
+        elif self.type == StringType and not is_optional:
+            return "%s = \"\";" % var
+        else:
+            pattern = {IntegerType: '%s = 0;',
+                       RealType: '%s = 0.0;',
+                       UuidType: 'uuid_zero(&%s);',
+                       BooleanType: '%s = false;',
+                       StringType: '%s = NULL;'}[self.type]
+            return pattern % var
+            
+    def cInitBaseType(self, indent, var):
+        stmts = []
+        stmts.append('ovsdb_base_type_init(&%s, OVSDB_TYPE_%s);' % (
+                var, self.type.to_string().upper()),)
+        if self.enum:
+            stmts.append("%s.enum_ = xmalloc(sizeof *%s.enum_);"
+                         % (var, var))
+            stmts += self.enum.cInitDatum("%s.enum_" % var)
+        if self.type == IntegerType:
+            if self.min is not None:
+                stmts.append('%s.u.integer.min = INT64_C(%d);' % (var, self.min))
+            if self.max is not None:
+                stmts.append('%s.u.integer.max = INT64_C(%d);' % (var, self.max))
+        elif self.type == RealType:
+            if self.min is not None:
+                stmts.append('%s.u.real.min = %d;' % (var, self.min))
+            if self.max is not None:
+                stmts.append('%s.u.real.max = %d;' % (var, self.max))
+        elif self.type == StringType:
+            if self.min_length is not None:
+                stmts.append('%s.u.string.minLen = %d;' % (var, self.min_length))            
+            if self.max_length is not None:
+                stmts.append('%s.u.string.maxLen = %d;' % (var, self.max_length))
+        elif self.type == UuidType:
+            if self.ref_table is not None:
+                stmts.append('%s.u.uuid.refTableName = "%s";' % (var, escapeCString(self.ref_table)))
+        return '\n'.join([indent + stmt for stmt in stmts])
+
+class Type(object):
+    def __init__(self, key, value=None, n_min=1, n_max=1):
+        self.key = key
+        self.value = value
+        self.n_min = n_min
+        self.n_max = n_max
+
+    def clone(self):
+        if self.value is None:
+            value = None
+        else:
+            value = self.value.clone()
+        return Type(self.key.clone(), value, self.n_min, self.n_max)
+
+    def __eq__(self, other):
+        if not isinstance(other, Type):
+            return NotImplemented
+        return (self.key == other.key and self.value == other.value and
+                self.n_min == other.n_min and self.n_max == other.n_max)
+
+    def __ne__(self, other):
+        if not isinstance(other, BaseType):
+            return NotImplemented
+        else:
+            return not (self == other)
+
+    def is_valid(self):
+        return (self.key.type != VoidType and self.key.is_valid() and
+                (self.value is None or
+                 (self.value.type != VoidType and self.value.is_valid())) and
+                self.n_min <= 1 and
+                self.n_min <= self.n_max and
+                self.n_max >= 1)
+
+    def is_scalar(self):
+        return self.n_min == 1 and self.n_max == 1 and not self.value
+
+    def is_optional(self):
+        return self.n_min == 0 and self.n_max == 1
+
+    def is_composite(self):
+        return self.n_max > 1
+
+    def is_set(self):
+        return self.value is None and (self.n_min != 1 or self.n_max != 1)
+
+    def is_map(self):
+        return self.value is not None
+
+    def is_optional_pointer(self):
+        return (self.is_optional() and not self.value
+                and (self.key.type == StringType or self.key.ref_table))
+
+    @staticmethod
+    def __n_from_json(json, default):
+        if json is None:
+            return default
+        elif type(json) == int and json >= 0 and json <= sys.maxint:
+            return json
+        else:
+            raise error.Error("bad min or max value", json)
+    
+    @staticmethod
+    def from_json(json):
+        if type(json) in [str, unicode]:
+            return Type(BaseType.from_json(json))
+
+        parser = ovs.db.parser.Parser(json, "ovsdb type")
+        key_json = parser.get("key", [dict, unicode])
+        value_json = parser.get_optional("value", [dict, unicode])
+        min_json = parser.get_optional("min", [int])
+        max_json = parser.get_optional("max", [int, str, unicode])
+        parser.finish()
+
+        key = BaseType.from_json(key_json)
+        if value_json:
+            value = BaseType.from_json(value_json)
+        else:
+            value = None
+
+        n_min = Type.__n_from_json(min_json, 1)
+
+        if max_json == 'unlimited':
+            n_max = sys.maxint
+        else:
+            n_max = Type.__n_from_json(max_json, 1)            
+
+        type_ = Type(key, value, n_min, n_max)
+        if not type_.is_valid():
+            raise error.Error("ovsdb type fails constraint checks", json)
+        return type_
+
+    def to_json(self):
+        if self.is_scalar() and not self.key.has_constraints():
+            return self.key.to_json()
+
+        json = {"key": self.key.to_json()}
+        if self.value is not None:
+            json["value"] = self.value.to_json()
+        if self.n_min != 1:
+            json["min"] = self.n_min
+        if self.n_max == sys.maxint:
+            json["max"] = "unlimited"
+        elif self.n_max != 1:
+            json["max"] = self.n_max
+        return json
+
+    def toEnglish(self, escapeLiteral=returnUnchanged):
+        keyName = self.key.toEnglish(escapeLiteral)
+        if self.value:
+            valueName = self.value.toEnglish(escapeLiteral)
+
+        if self.is_scalar():
+            return keyName
+        elif self.is_optional():
+            if self.value:
+                return "optional %s-%s pair" % (keyName, valueName)
+            else:
+                return "optional %s" % keyName
+        else:
+            if self.n_max == sys.maxint:
+                if self.n_min:
+                    quantity = "%d or more " % self.n_min
+                else:
+                    quantity = ""
+            elif self.n_min:
+                quantity = "%d to %d " % (self.n_min, self.n_max)
+            else:
+                quantity = "up to %d " % self.n_max
+
+            if self.value:
+                return "map of %s%s-%s pairs" % (quantity, keyName, valueName)
+            else:
+                if keyName.endswith('s'):
+                    plural = keyName + "es"
+                else:
+                    plural = keyName + "s"
+                return "set of %s%s" % (quantity, plural)
+
+    def constraintsToEnglish(self, escapeLiteral=returnUnchanged):
+        s = ""
+
+        constraints = []
+        keyConstraints = self.key.constraintsToEnglish(escapeLiteral)
+        if keyConstraints:
+            if self.value:
+                constraints += ['key ' + keyConstraints]
+            else:
+                constraints += [keyConstraints]
+
+        if self.value:
+            valueConstraints = self.value.constraintsToEnglish(escapeLiteral)
+            if valueConstraints:
+                constraints += ['value ' + valueConstraints]
+
+        return ', '.join(constraints)
+                
+    def cDeclComment(self):
+        if self.n_min == 1 and self.n_max == 1 and self.key.type == StringType:
+            return "\t/* Always nonnull. */"
+        else:
+            return ""
+
+    def cInitType(self, indent, var):
+        initKey = self.key.cInitBaseType(indent, "%s.key" % var)
+        if self.value:
+            initValue = self.value.cInitBaseType(indent, "%s.value" % var)
+        else:
+            initValue = ('%sovsdb_base_type_init(&%s.value, '
+                         'OVSDB_TYPE_VOID);' % (indent, var))
+        initMin = "%s%s.n_min = %s;" % (indent, var, self.n_min)
+        if self.n_max == sys.maxint:
+            max = "UINT_MAX"
+        else:
+            max = self.n_max
+        initMax = "%s%s.n_max = %s;" % (indent, var, max)
+        return "\n".join((initKey, initValue, initMin, initMax))
+
diff --git a/python/ovs/dirs.py b/python/ovs/dirs.py
new file mode 100644
index 000000000..f8e73087f
--- /dev/null
+++ b/python/ovs/dirs.py
@@ -0,0 +1,7 @@
+# These are the default directories.  They will be replaced by the
+# configured directories at install time.
+
+PKGDATADIR = "/usr/local/share/openvswitch"
+RUNDIR = "/var/run"
+LOGDIR = "/usr/local/var/log"
+BINDIR = "/usr/local/bin"
diff --git a/python/ovs/fatal_signal.py b/python/ovs/fatal_signal.py
new file mode 100644
index 000000000..5fca820e6
--- /dev/null
+++ b/python/ovs/fatal_signal.py
@@ -0,0 +1,121 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import atexit
+import logging
+import os
+import signal
+
+_inited = False
+_hooks = []
+
+def _init():
+    global _inited
+    if not _inited:
+        _inited = True
+
+        for signr in (signal.SIGTERM, signal.SIGINT,
+                      signal.SIGHUP, signal.SIGALRM):
+            if signal.getsignal(signr) == signal.SIG_DFL:
+                signal.signal(signr, _signal_handler)
+        atexit.register(_atexit_handler)
+
+def add_hook(hook, cancel, run_at_exit):
+    _init()
+
+    global _hooks
+    _hooks.append((hook, cancel, run_at_exit))
+
+def fork():
+    """Clears all of the fatal signal hooks without executing them.  If any of
+    the hooks passed a 'cancel' function to add_hook(), then those functions
+    will be called, allowing them to free resources, etc.
+
+    Following a fork, one of the resulting processes can call this function to
+    allow it to terminate without calling the hooks registered before calling
+    this function.  New hooks registered after calling this function will take
+    effect normally."""
+    global _hooks
+    for hook, cancel, run_at_exit in _hooks:
+        if cancel:
+            cancel()
+
+    _hooks = []
+
+_added_hook = False
+_files = {}
+
+def add_file_to_unlink(file):
+    """Registers 'file' to be unlinked when the program terminates via
+    sys.exit() or a fatal signal."""
+    global _added_hook
+    if not _added_hook:
+        _added_hook = True
+        add_hook(_unlink_files, _cancel_files, True)
+    _files[file] = None
+
+def remove_file_to_unlink(file):
+    """Unregisters 'file' from being unlinked when the program terminates via
+    sys.exit() or a fatal signal."""
+    if file in _files:
+        del _files[file]
+
+def unlink_file_now(file):
+    """Like fatal_signal_remove_file_to_unlink(), but also unlinks 'file'.
+    Returns 0 if successful, otherwise a positive errno value."""
+    error = _unlink(file)
+    if error:
+        logging.warning("could not unlink \"%s\" (%s)"
+                        % (file, os.strerror(error)))
+    remove_file_to_unlink(file)
+    return error
+
+def _unlink_files():
+    for file in _files:
+        _unlink(file)
+
+def _cancel_files():
+    global _added_hook
+    global _files
+    _added_hook = False
+    _files = {}
+
+def _unlink(file):
+    try:
+        os.unlink(file)
+        return 0
+    except OSError, e:
+        return e.errno
+
+def _signal_handler(signr, frame):
+    _call_hooks(signr)
+
+    # Re-raise the signal with the default handling so that the program
+    # termination status reflects that we were killed by this signal.
+    signal.signal(signr, signal.SIG_DFL)
+    os.kill(os.getpid(), signr)
+
+def _atexit_handler():
+    _call_hooks(0)
+
+recurse = False
+def _call_hooks(signr):
+    global recurse
+    if recurse:
+        return
+    recurse = True
+
+    for hook, cancel, run_at_exit in _hooks:
+        if signr != 0 or run_at_exit:
+            hook()
diff --git a/python/ovs/json.py b/python/ovs/json.py
new file mode 100644
index 000000000..1e26a6290
--- /dev/null
+++ b/python/ovs/json.py
@@ -0,0 +1,528 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import re
+import StringIO
+import sys
+
+escapes = {ord('"'): u"\\\"",
+           ord("\\"): u"\\\\",
+           ord("\b"): u"\\b",
+           ord("\f"): u"\\f",
+           ord("\n"): u"\\n",
+           ord("\r"): u"\\r",
+           ord("\t"): u"\\t"}
+for i in range(32):
+    if i not in escapes:
+        escapes[i] = u"\\u%04x" % i
+
+def __dump_string(stream, s):
+    stream.write(u"\"")
+    for c in s:
+        x = ord(c)
+        escape = escapes.get(x)
+        if escape:
+            stream.write(escape)
+        else:
+            stream.write(c)
+    stream.write(u"\"")
+
+def to_stream(obj, stream, pretty=False, sort_keys=True):
+    if obj is None:
+        stream.write(u"null")
+    elif obj is False:
+        stream.write(u"false")
+    elif obj is True:
+        stream.write(u"true")
+    elif type(obj) in (int, long):
+        stream.write(u"%d" % obj)
+    elif type(obj) == float:
+        stream.write("%.15g" % obj)
+    elif type(obj) == unicode:
+        __dump_string(stream, obj)
+    elif type(obj) == str:
+        __dump_string(stream, unicode(obj))
+    elif type(obj) == dict:
+        stream.write(u"{")
+        if sort_keys:
+            items = sorted(obj.items())
+        else:
+            items = obj.iteritems()
+        i = 0
+        for key, value in items:
+            if i > 0:
+                stream.write(u",")
+            i += 1
+            __dump_string(stream, unicode(key))
+            stream.write(u":")
+            to_stream(value, stream, pretty, sort_keys)
+        stream.write(u"}")
+    elif type(obj) in (list, tuple):
+        stream.write(u"[")
+        i = 0
+        for value in obj:
+            if i > 0:
+                stream.write(u",")
+            i += 1
+            to_stream(value, stream, pretty, sort_keys)
+        stream.write(u"]")
+    else:
+        raise Error("can't serialize %s as JSON" % obj)
+
+def to_file(obj, name, pretty=False, sort_keys=True):
+    stream = open(name, "w")
+    try:
+        to_stream(obj, stream, pretty, sort_keys)
+    finally:
+        stream.close()
+
+def to_string(obj, pretty=False, sort_keys=True):
+    output = StringIO.StringIO()
+    to_stream(obj, output, pretty, sort_keys)
+    s = output.getvalue()
+    output.close()
+    return s
+
+def from_stream(stream):
+    p = Parser(check_trailer=True)
+    while True:
+        buf = stream.read(4096)
+        if buf == "" or p.feed(buf) != len(buf):
+            break
+    return p.finish()
+
+def from_file(name):
+    stream = open(name, "r")
+    try:
+        return from_stream(stream)
+    finally:
+        stream.close()
+
+def from_string(s):
+    try:
+        s = unicode(s, 'utf-8')
+    except UnicodeDecodeError, e:
+        seq = ' '.join(["0x%2x" % ord(c) for c in e.object[e.start:e.end]])
+        raise Error("\"%s\" is not a valid UTF-8 string: "
+                    "invalid UTF-8 sequence %s" % (s, seq),
+                    tag="constraint violation")
+    p = Parser(check_trailer=True)
+    p.feed(s)
+    return p.finish()
+
+class Parser(object):
+    ## Maximum height of parsing stack. ##
+    MAX_HEIGHT = 1000
+
+    def __init__(self, check_trailer=False):
+        self.check_trailer = check_trailer
+
+        # Lexical analysis.
+        self.lex_state = Parser.__lex_start
+        self.buffer = ""
+        self.line_number = 0
+        self.column_number = 0
+        self.byte_number = 0
+        
+        # Parsing.
+        self.parse_state = Parser.__parse_start
+        self.stack = []
+        self.member_name = None
+
+        # Parse status.
+        self.done = False
+        self.error = None
+
+    def __lex_start_space(self, c):
+        pass
+    def __lex_start_alpha(self, c):
+        self.buffer = c
+        self.lex_state = Parser.__lex_keyword
+    def __lex_start_token(self, c):
+        self.__parser_input(c)
+    def __lex_start_number(self, c):
+        self.buffer = c
+        self.lex_state = Parser.__lex_number
+    def __lex_start_string(self, c):
+        self.lex_state = Parser.__lex_string
+    def __lex_start_error(self, c):
+        if ord(c) >= 32 and ord(c) < 128:
+            self.__error("invalid character '%s'" % c)
+        else:
+            self.__error("invalid character U+%04x" % ord(c))
+
+    __lex_start_actions = {}
+    for c in " \t\n\r":
+        __lex_start_actions[c] = __lex_start_space
+    for c in "abcdefghijklmnopqrstuvwxyz":
+        __lex_start_actions[c] = __lex_start_alpha
+    for c in "[{]}:,":
+        __lex_start_actions[c] = __lex_start_token
+    for c in "-0123456789":
+        __lex_start_actions[c] = __lex_start_number
+    __lex_start_actions['"'] = __lex_start_string
+    def __lex_start(self, c):
+        Parser.__lex_start_actions.get(
+            c, Parser.__lex_start_error)(self, c)
+        return True
+
+    __lex_alpha = {}
+    for c in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ":
+        __lex_alpha[c] = True
+    def __lex_finish_keyword(self):
+        if self.buffer == "false":
+            self.__parser_input(False)
+        elif self.buffer == "true":
+            self.__parser_input(True)
+        elif self.buffer == "null":
+            self.__parser_input(None)
+        else:
+            self.__error("invalid keyword '%s'" % self.buffer)
+    def __lex_keyword(self, c):
+        if c in Parser.__lex_alpha:
+            self.buffer += c
+            return True
+        else:
+            self.__lex_finish_keyword()
+            return False
+
+    __number_re = re.compile("(-)?(0|[1-9][0-9]*)(?:\.([0-9]+))?(?:[eE]([-+]?[0-9]+))?$")
+    def __lex_finish_number(self):
+        s = self.buffer
+        m = Parser.__number_re.match(s)
+        if m:
+            sign, integer, fraction, exp = m.groups() 
+            if (exp is not None and
+                (long(exp) > sys.maxint or long(exp) < -sys.maxint - 1)):
+                self.__error("exponent outside valid range")
+                return
+
+            if fraction is not None and len(fraction.lstrip('0')) == 0:
+                fraction = None
+
+            sig_string = integer
+            if fraction is not None:
+                sig_string += fraction
+            significand = int(sig_string)
+
+            pow10 = 0
+            if fraction is not None:
+                pow10 -= len(fraction)
+            if exp is not None:
+                pow10 += long(exp)
+
+            if significand == 0:
+                self.__parser_input(0)
+                return
+            elif significand <= 2**63:
+                while pow10 > 0 and significand <= 2*63:
+                    significand *= 10
+                    pow10 -= 1
+                while pow10 < 0 and significand % 10 == 0:
+                    significand /= 10
+                    pow10 += 1
+                if (pow10 == 0 and
+                    ((not sign and significand < 2**63) or
+                     (sign and significand <= 2**63))):
+                    if sign:
+                        self.__parser_input(-significand)
+                    else:
+                        self.__parser_input(significand)
+                    return
+
+            value = float(s)
+            if value == float("inf") or value == float("-inf"):
+                self.__error("number outside valid range")
+                return
+            if value == 0:
+                # Suppress negative zero.
+                value = 0
+            self.__parser_input(value)
+        elif re.match("-?0[0-9]", s):
+            self.__error("leading zeros not allowed")
+        elif re.match("-([^0-9]|$)", s):
+            self.__error("'-' must be followed by digit")
+        elif re.match("-?(0|[1-9][0-9]*)\.([^0-9]|$)", s):
+            self.__error("decimal point must be followed by digit")
+        elif re.search("e[-+]?([^0-9]|$)", s):
+            self.__error("exponent must contain at least one digit")
+        else:
+            self.__error("syntax error in number")
+            
+    def __lex_number(self, c):
+        if c in ".0123456789eE-+":
+            self.buffer += c
+            return True
+        else:
+            self.__lex_finish_number()
+            return False
+
+    __4hex_re = re.compile("[0-9a-fA-F]{4}")
+    def __lex_4hex(self, s):
+        if len(s) < 4:
+            self.__error("quoted string ends within \\u escape")
+        elif not Parser.__4hex_re.match(s):
+            self.__error("malformed \\u escape")
+        elif s == "0000":
+            self.__error("null bytes not supported in quoted strings")
+        else:
+            return int(s, 16)
+    @staticmethod
+    def __is_leading_surrogate(c):
+        """Returns true if 'c' is a Unicode code point for a leading
+        surrogate."""
+        return c >= 0xd800 and c <= 0xdbff
+    @staticmethod
+    def __is_trailing_surrogate(c):
+        """Returns true if 'c' is a Unicode code point for a trailing
+        surrogate."""
+        return c >= 0xdc00 and c <= 0xdfff
+    @staticmethod
+    def __utf16_decode_surrogate_pair(leading, trailing):
+        """Returns the unicode code point corresponding to leading surrogate
+        'leading' and trailing surrogate 'trailing'.  The return value will not
+        make any sense if 'leading' or 'trailing' are not in the correct ranges
+        for leading or trailing surrogates."""
+        #  Leading surrogate:         110110wwwwxxxxxx
+        # Trailing surrogate:         110111xxxxxxxxxx
+        #         Code point: 000uuuuuxxxxxxxxxxxxxxxx
+        w = (leading >> 6) & 0xf
+        u = w + 1
+        x0 = leading & 0x3f
+        x1 = trailing & 0x3ff
+        return (u << 16) | (x0 << 10) | x1
+    __unescape = {'"': u'"',
+                  "\\": u"\\",
+                  "/": u"/",
+                  "b": u"\b",
+                  "f": u"\f",
+                  "n": u"\n",
+                  "r": u"\r",
+                  "t": u"\t"}
+    def __lex_finish_string(self):
+        inp = self.buffer
+        out = u""
+        while len(inp):
+            backslash = inp.find('\\')
+            if backslash == -1:
+                out += inp
+                break
+            out += inp[:backslash]
+            inp = inp[backslash + 1:]
+            if inp == "":
+                self.__error("quoted string may not end with backslash")
+                return
+
+            replacement = Parser.__unescape.get(inp[0])
+            if replacement is not None:
+                out += replacement
+                inp = inp[1:]
+                continue
+            elif inp[0] != u'u':
+                self.__error("bad escape \\%s" % inp[0])
+                return
+            
+            c0 = self.__lex_4hex(inp[1:5])
+            if c0 is None:
+                return
+            inp = inp[5:]
+
+            if Parser.__is_leading_surrogate(c0):
+                if inp[:2] != u'\\u':
+                    self.__error("malformed escaped surrogate pair")
+                    return
+                c1 = self.__lex_4hex(inp[2:6])
+                if c1 is None:
+                    return
+                if not Parser.__is_trailing_surrogate(c1):
+                    self.__error("second half of escaped surrogate pair is "
+                                 "not trailing surrogate")
+                    return
+                code_point = Parser.__utf16_decode_surrogate_pair(c0, c1)
+                inp = inp[6:]
+            else:
+                code_point = c0
+            out += unichr(code_point)
+        self.__parser_input('string', out)
+
+    def __lex_string_escape(self, c):
+        self.buffer += c
+        self.lex_state = Parser.__lex_string
+        return True
+    def __lex_string(self, c):
+        if c == '\\':
+            self.buffer += c
+            self.lex_state = Parser.__lex_string_escape
+        elif c == '"':
+            self.__lex_finish_string()
+        elif ord(c) >= 0x20:
+            self.buffer += c
+        else:
+            self.__error("U+%04X must be escaped in quoted string" % ord(c))
+        return True
+
+    def __lex_input(self, c):
+        self.byte_number += 1
+        if c == '\n':
+            self.column_number = 0
+            self.line_number += 1
+        else:
+            self.column_number += 1
+
+        eat = self.lex_state(self, c)
+        assert eat is True or eat is False
+        return eat
+
+    def __parse_start(self, token, string):
+        if token == '{':
+            self.__push_object()
+        elif token == '[':
+            self.__push_array()
+        else:
+            self.__error("syntax error at beginning of input")
+    def __parse_end(self, token, string):
+        self.__error("trailing garbage at end of input")
+    def __parse_object_init(self, token, string):
+        if token == '}':
+            self.__parser_pop()
+        else:
+            self.__parse_object_name(token, string)
+    def __parse_object_name(self, token, string):
+        if token == 'string':
+            self.member_name = string
+            self.parse_state = Parser.__parse_object_colon
+        else:
+            self.__error("syntax error parsing object expecting string")
+    def __parse_object_colon(self, token, string):
+        if token == ":":
+            self.parse_state = Parser.__parse_object_value
+        else:
+            self.__error("syntax error parsing object expecting ':'")
+    def __parse_object_value(self, token, string):
+        self.__parse_value(token, string, Parser.__parse_object_next)
+    def __parse_object_next(self, token, string):
+        if token == ",":
+            self.parse_state = Parser.__parse_object_name
+        elif token == "}":
+            self.__parser_pop()
+        else:
+            self.__error("syntax error expecting '}' or ','")
+    def __parse_array_init(self, token, string):
+        if token == ']':
+            self.__parser_pop()
+        else:
+            self.__parse_array_value(token, string)
+    def __parse_array_value(self, token, string):
+        self.__parse_value(token, string, Parser.__parse_array_next)
+    def __parse_array_next(self, token, string):
+        if token == ",":
+            self.parse_state = Parser.__parse_array_value
+        elif token == "]":
+            self.__parser_pop()
+        else:
+            self.__error("syntax error expecting ']' or ','")
+    def __parser_input(self, token, string=None):
+        self.lex_state = Parser.__lex_start
+        self.buffer = ""
+        #old_state = self.parse_state
+        self.parse_state(self, token, string)
+        #print ("token=%s string=%s old_state=%s new_state=%s"
+        #       % (token, string, old_state, self.parse_state))
+
+    def __put_value(self, value):
+        top = self.stack[-1]
+        if type(top) == dict:
+            top[self.member_name] = value
+        else:
+            top.append(value)
+
+    def __parser_push(self, new_json, next_state):
+        if len(self.stack) < Parser.MAX_HEIGHT:
+            if len(self.stack) > 0:
+                self.__put_value(new_json)
+            self.stack.append(new_json)
+            self.parse_state = next_state
+        else:
+            self.__error("input exceeds maximum nesting depth %d" %
+                         Parser.MAX_HEIGHT)
+    def __push_object(self):
+        self.__parser_push({}, Parser.__parse_object_init)
+    def __push_array(self):
+        self.__parser_push([], Parser.__parse_array_init)
+
+    def __parser_pop(self):
+        if len(self.stack) == 1:
+            self.parse_state = Parser.__parse_end
+            if not self.check_trailer:
+                self.done = True
+        else:
+            self.stack.pop()
+            top = self.stack[-1]
+            if type(top) == list:
+                self.parse_state = Parser.__parse_array_next
+            else:
+                self.parse_state = Parser.__parse_object_next
+
+    def __parse_value(self, token, string, next_state):
+        if token in [False, None, True] or type(token) in [int, long, float]:
+            self.__put_value(token)
+        elif token == 'string':
+            self.__put_value(string)
+        else:
+            if token == '{':
+                self.__push_object()
+            elif token == '[':
+                self.__push_array()
+            else:
+                self.__error("syntax error expecting value")
+            return
+        self.parse_state = next_state
+
+    def __error(self, message):
+        if self.error is None:
+            self.error = ("line %d, column %d, byte %d: %s"
+                          % (self.line_number, self.column_number,
+                             self.byte_number, message))
+            self.done = True
+
+    def feed(self, s):
+        i = 0
+        while True:
+            if self.done or i >= len(s):
+                return i
+            if self.__lex_input(s[i]):
+                i += 1
+
+    def is_done(self):
+        return self.done
+
+    def finish(self):
+        if self.lex_state == Parser.__lex_start:
+            pass
+        elif self.lex_state in (Parser.__lex_string,
+                                Parser.__lex_string_escape):
+            self.__error("unexpected end of input in quoted string")
+        else:
+            self.__lex_input(" ")
+
+        if self.parse_state == Parser.__parse_start:
+            self.__error("empty input stream")
+        elif self.parse_state != Parser.__parse_end:
+            self.__error("unexpected end of input")
+
+        if self.error == None:
+            assert len(self.stack) == 1
+            return self.stack.pop()
+        else:
+            return self.error
diff --git a/python/ovs/jsonrpc.py b/python/ovs/jsonrpc.py
new file mode 100644
index 000000000..975d40f71
--- /dev/null
+++ b/python/ovs/jsonrpc.py
@@ -0,0 +1,526 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+import logging
+import os
+
+import ovs.poller
+import ovs.reconnect
+import ovs.stream
+import ovs.timeval
+
+EOF = -1
+
+class Message(object):
+    T_REQUEST = 0               # Request.
+    T_NOTIFY = 1                # Notification.
+    T_REPLY = 2                 # Successful reply.
+    T_ERROR = 3                 # Error reply.
+
+    __types = {T_REQUEST: "request",
+               T_NOTIFY: "notification",
+               T_REPLY: "reply",
+               T_ERROR: "error"}
+    __next_id = 0
+
+    def __init__(self, type, method, params, result, error, id):
+        self.type = type
+        self.method = method
+        self.params = params
+        self.result = result
+        self.error = error
+        self.id = id
+
+    _next_id = 0
+    @staticmethod
+    def _create_id():
+        this_id = Message._next_id
+        Message._next_id += 1
+        return this_id
+
+    @staticmethod
+    def create_request(method, params):
+        return Message(Message.T_REQUEST, method, params, None, None,
+                       Message._create_id())
+
+    @staticmethod
+    def create_notify(method, params):
+        return Message(Message.T_NOTIFY, method, params, None, None,
+                       None)
+
+    @staticmethod
+    def create_reply(result, id):
+        return Message(Message.T_REPLY, None, None, result, None, id)
+
+    @staticmethod
+    def create_error(error, id):
+        return Message(Message.T_ERROR, None, None, None, error, id)
+
+    @staticmethod
+    def type_to_string(type):
+        return Message.__types[type]
+
+    @staticmethod
+    def __validate_arg(value, name, must_have):
+        if (value is not None) == (must_have != 0):
+            return None
+        else:
+            type_name = Message.type_to_string(self.type)
+            if must_have:
+                verb = "must"
+            else:
+                verb = "must not"
+            return "%s %s have \"%s\"" % (type_name, verb, name)
+
+    def is_valid(self):
+        if self.params is not None and type(self.params) != list:
+            return "\"params\" must be JSON array"
+
+        pattern = {Message.T_REQUEST: 0x11001,
+                   Message.T_NOTIFY:  0x11000,
+                   Message.T_REPLY:   0x00101,
+                   Message.T_ERROR:   0x00011}.get(self.type)
+        if pattern is None:
+            return "invalid JSON-RPC message type %s" % self.type
+
+        return (
+            Message.__validate_arg(self.method, "method", pattern & 0x10000) or
+            Message.__validate_arg(self.params, "params", pattern & 0x1000) or
+            Message.__validate_arg(self.result, "result", pattern & 0x100) or
+            Message.__validate_arg(self.error, "error", pattern & 0x10) or
+            Message.__validate_arg(self.id, "id", pattern & 0x1))
+
+    @staticmethod
+    def from_json(json):
+        if type(json) != dict:
+            return "message is not a JSON object"
+
+        # Make a copy to avoid modifying the caller's dict.
+        json = dict(json)
+
+        if "method" in json:
+            method = json.pop("method")
+            if type(method) not in [str, unicode]:
+                return "method is not a JSON string"
+        else:
+            method = None
+
+        params = json.pop("params", None)
+        result = json.pop("result", None)
+        error = json.pop("error", None)
+        id = json.pop("id", None)
+        if len(json):
+            return "message has unexpected member \"%s\"" % json.popitem()[0]
+
+        if result is not None:
+            msg_type = Message.T_REPLY
+        elif error is not None:
+            msg_type = Message.T_ERROR
+        elif id is not None:
+            msg_type = Message.T_REQUEST
+        else:
+            msg_type = Message.T_NOTIFY
+        
+        msg = Message(msg_type, method, params, result, error, id)
+        validation_error = msg.is_valid()
+        if validation_error is not None:
+            return validation_error
+        else:
+            return msg
+
+    def to_json(self):
+        json = {}
+
+        if self.method is not None:
+            json["method"] = self.method
+
+        if self.params is not None:
+            json["params"] = self.params
+
+        if self.result is not None or self.type == Message.T_ERROR:
+            json["result"] = self.result
+
+        if self.error is not None or self.type == Message.T_REPLY:
+            json["error"] = self.error
+
+        if self.id is not None or self.type == Message.T_NOTIFY:
+            json["id"] = self.id
+
+        return json
+
+    def __str__(self):
+        s = [Message.type_to_string(self.type)]
+        if self.method is not None:
+            s.append("method=\"%s\"" % self.method)
+        if self.params is not None:
+            s.append("params=" + ovs.json.to_string(self.params))
+        if self.error is not None:
+            s.append("error=" + ovs.json.to_string(self.error))
+        if self.id is not None:
+            s.append("id=" + ovs.json.to_string(self.id))
+        return ", ".join(s)
+
+class Connection(object):
+    def __init__(self, stream):
+        self.name = stream.get_name()
+        self.stream = stream
+        self.status = 0
+        self.input = ""
+        self.output = ""
+        self.parser = None
+
+    def close(self):
+        self.stream.close()
+        self.stream = None
+
+    def run(self):
+        if self.status:
+            return
+
+        while len(self.output):
+            retval = self.stream.send(self.output)
+            if retval >= 0:
+                self.output = self.output[retval:]
+            else:
+                if retval != -errno.EAGAIN:
+                    logging.warn("%s: send error: %s" % (self.name,
+                                                         os.strerror(-retval)))
+                    self.error(-retval)
+                break
+
+    def wait(self, poller):
+        if not self.status:
+            self.stream.run_wait(poller)
+            if len(self.output):
+                self.stream.send_wait()
+
+    def get_status(self):
+        return self.status
+
+    def get_backlog(self):
+        if self.status != 0:
+            return 0
+        else:
+            return len(self.output)
+
+    def get_name(self):
+        return self.name
+
+    def __log_msg(self, title, msg):
+        logging.debug("%s: %s %s" % (self.name, title, msg))
+
+    def send(self, msg):
+        if self.status:
+            return self.status
+
+        self.__log_msg("send", msg)
+
+        was_empty = len(self.output) == 0
+        self.output += ovs.json.to_string(msg.to_json())
+        if was_empty:
+            self.run()
+        return self.status
+
+    def send_block(self, msg):
+        error = self.send(msg)
+        if error:
+            return error
+
+        while True:
+            self.run()
+            if not self.get_backlog() or self.get_status():
+                return self.status
+
+            poller = ovs.poller.Poller()
+            self.wait(poller)
+            poller.block()
+
+    def recv(self):
+        if self.status:
+            return self.status, None
+
+        while True:
+            if len(self.input) == 0:
+                error, data = self.stream.recv(4096)
+                if error:
+                    if error == errno.EAGAIN:
+                        return error, None
+                    else:
+                        # XXX rate-limit
+                        logging.warning("%s: receive error: %s"
+                                        % (self.name, os.strerror(error)))
+                        self.error(error)
+                        return self.status, None
+                elif len(data) == 0:
+                    self.error(EOF)
+                    return EOF, None
+                else:
+                    self.input += data
+            else:
+                if self.parser is None:
+                    self.parser = ovs.json.Parser()
+                self.input = self.input[self.parser.feed(self.input):]
+                if self.parser.is_done():
+                    msg = self.__process_msg()
+                    if msg:
+                        return 0, msg
+                    else:
+                        return self.status, None
+
+    def recv_block(self):
+        while True:
+            error, msg = self.recv()
+            if error != errno.EAGAIN:
+                return error, msg
+
+            self.run()
+
+            poller = ovs.poller.Poller()
+            self.wait(poller)
+            self.recv_wait(poller)
+            poller.block()
+    
+    def transact_block(self, request):
+        id = request.id
+
+        error = self.send(request)
+        reply = None
+        while not error:
+            error, reply = self.recv_block()
+            if reply and reply.type == Message.T_REPLY and reply.id == id:
+                break
+        return error, reply
+
+    def __process_msg(self):
+        json = self.parser.finish()
+        self.parser = None
+        if type(json) in [str, unicode]:
+            # XXX rate-limit
+            logging.warning("%s: error parsing stream: %s" % (self.name, json))
+            self.error(errno.EPROTO)
+            return
+
+        msg = Message.from_json(json)
+        if not isinstance(msg, Message):
+            # XXX rate-limit
+            logging.warning("%s: received bad JSON-RPC message: %s"
+                            % (self.name, msg))
+            self.error(errno.EPROTO)
+            return
+
+        self.__log_msg("received", msg)
+        return msg
+        
+    def recv_wait(self, poller):
+        if self.status or len(self.input) > 0:
+            poller.immediate_wake()
+        else:
+            self.stream.recv_wait(poller)
+
+    def error(self, error):
+        if self.status == 0:
+            self.status = error
+            self.stream.close()
+            self.output = ""
+            
+class Session(object):
+    """A JSON-RPC session with reconnection."""
+
+    def __init__(self, reconnect, rpc):
+        self.reconnect = reconnect
+        self.rpc = rpc
+        self.stream = None
+        self.pstream = None
+        self.seqno = 0
+
+    @staticmethod
+    def open(name):
+        """Creates and returns a Session that maintains a JSON-RPC session to
+        'name', which should be a string acceptable to ovs.stream.Stream or
+        ovs.stream.PassiveStream's initializer.
+        
+        If 'name' is an active connection method, e.g. "tcp:127.1.2.3", the new
+        session connects and reconnects, with back-off, to 'name'.
+        
+        If 'name' is a passive connection method, e.g. "ptcp:", the new session
+        listens for connections to 'name'.  It maintains at most one connection
+        at any given time.  Any new connection causes the previous one (if any)
+        to be dropped."""
+        reconnect = ovs.reconnect.Reconnect(ovs.timeval.msec())
+        reconnect.set_name(name)
+        reconnect.enable(ovs.timeval.msec())
+
+        if ovs.stream.PassiveStream.is_valid_name(name):
+            self.reconnect.set_passive(True, ovs.timeval.msec())
+
+        return Session(reconnect, None)
+
+    @staticmethod
+    def open_unreliably(jsonrpc):
+        reconnect = ovs.reconnect.Reconnect(ovs.timeval.msec())
+        reconnect.set_quiet(True)
+        reconnect.set_name(jsonrpc.get_name())
+        reconnect.set_max_tries(0)
+        reconnect.connected(ovs.timeval.msec())
+        return Session(reconnect, jsonrpc)
+
+    def close(self):
+        if self.rpc is not None:
+            self.rpc.close()
+            self.rpc = None
+        if self.stream is not None:
+            self.stream.close()
+            self.stream = None
+        if self.pstream is not None:
+            self.pstream.close()
+            self.pstream = None
+
+    def __disconnect(self):
+        if self.rpc is not None:
+            self.rpc.error(EOF)
+            self.rpc.close()
+            self.rpc = None
+            self.seqno += 1
+        elif self.stream is not None:
+            self.stream.close()
+            self.stream = None
+            self.seqno += 1
+    
+    def __connect(self):
+        self.__disconnect()
+
+        name = self.reconnect.get_name()
+        if not self.reconnect.is_passive():
+            error, self.stream = ovs.stream.Stream.open(name)
+            if not error:
+                self.reconnect.connecting(ovs.timeval.msec())
+            else:
+                self.reconnect.connect_failed(ovs.timeval.msec(), error)
+        elif self.pstream is not None:
+            error, self.pstream = ovs.stream.PassiveStream.open(name)
+            if not error:
+                self.reconnect.listening(ovs.timeval.msec())
+            else:
+                self.reconnect.connect_failed(ovs.timeval.msec(), error)
+
+        self.seqno += 1
+
+    def run(self):
+        if self.pstream is not None:
+            error, stream = self.pstream.accept()
+            if error == 0:
+                if self.rpc or self.stream:
+                    # XXX rate-limit
+                    logging.info("%s: new connection replacing active "
+                                 "connection" % self.reconnect.get_name())
+                    self.__disconnect()
+                self.reconnect.connected(ovs.timeval.msec())
+                self.rpc = Connection(stream)
+            elif error != errno.EAGAIN:
+                self.reconnect.listen_error(ovs.timeval.msec(), error)
+                self.pstream.close()
+                self.pstream = None
+
+        if self.rpc:
+            self.rpc.run()
+            error = self.rpc.get_status()
+            if error != 0:
+                self.reconnect.disconnected(ovs.timeval.msec(), error)
+                self.__disconnect()
+        elif self.stream is not None:
+            self.stream.run()
+            error = self.stream.connect()
+            if error == 0:
+                self.reconnect.connected(ovs.timeval.msec())
+                self.rpc = Connection(self.stream)
+                self.stream = None
+            elif error != errno.EAGAIN:
+                self.reconnect.connect_failed(ovs.timeval.msec(), error)
+                self.stream.close()
+                self.stream = None
+
+        action = self.reconnect.run(ovs.timeval.msec())
+        if action == ovs.reconnect.CONNECT:
+            self.__connect()
+        elif action == ovs.reconnect.DISCONNECT:
+            self.reconnect.disconnected(ovs.timeval.msec(), 0)
+            self.__disconnect()
+        elif action == ovs.reconnect.PROBE:
+            if self.rpc:
+                request = Message.create_request("echo", [])
+                request.id = "echo"
+                self.rpc.send(request)
+        else:
+            assert action == None
+
+    def wait(self, poller):
+        if self.rpc is not None:
+            self.rpc.wait(poller)
+        elif self.stream is not None:
+            self.stream.run_wait(poller)
+            self.stream.connect_wait(poller)
+        if self.pstream is not None:
+            self.pstream.wait(poller)
+        self.reconnect.wait(poller, ovs.timeval.msec())
+
+    def get_backlog(self):
+        if self.rpc is not None:
+            return self.rpc.get_backlog()
+        else:
+            return 0
+
+    def get_name(self):
+        return self.reconnect.get_name()
+
+    def send(self, msg):
+        if self.rpc is not None:
+            return self.rpc.send(msg)
+        else:
+            return errno.ENOTCONN
+
+    def recv(self):
+        if self.rpc is not None:
+            error, msg = self.rpc.recv()
+            if not error:
+                self.reconnect.received(ovs.timeval.msec())
+                if msg.type == Message.T_REQUEST and msg.method == "echo":
+                    # Echo request.  Send reply.
+                    self.send(Message.create_reply(msg.params, msg.id))
+                elif msg.type == Message.T_REPLY and msg.id == "echo":
+                    # It's a reply to our echo request.  Suppress it.
+                    pass
+                else:
+                    return msg
+        return None
+
+    def recv_wait(self, poller):
+        if self.rpc is not None:
+            self.rpc.recv_wait(poller)
+
+    def is_alive(self):
+        if self.rpc is not None or self.stream is not None:
+            return True
+        else:
+            max_tries = self.reconnect.get_max_tries()
+            return max_tries is None or max_tries > 0
+    
+    def is_connected(self):
+        return self.rpc is not None
+
+    def get_seqno(self):
+        return self.seqno
+
+    def force_reconnect(self):
+        self.reconnect.force_reconnect(ovs.timeval.msec())
diff --git a/python/ovs/ovsuuid.py b/python/ovs/ovsuuid.py
new file mode 100644
index 000000000..98c65f3db
--- /dev/null
+++ b/python/ovs/ovsuuid.py
@@ -0,0 +1,72 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import re
+import uuid
+
+from ovs.db import error
+import ovs.db.parser
+
+class UUID(uuid.UUID):
+    x = "[0-9a-fA-f]"
+    uuidRE = re.compile("^(%s{8})-(%s{4})-(%s{4})-(%s{4})-(%s{4})(%s{8})$"
+                        % (x, x, x, x, x, x))
+
+    def __init__(self, s):
+        uuid.UUID.__init__(self, hex=s)
+
+    @staticmethod
+    def zero():
+        return UUID('00000000-0000-0000-0000-000000000000')
+
+    def is_zero(self):
+        return self.int == 0
+
+    @staticmethod
+    def is_valid_string(s):
+        return UUID.uuidRE.match(s) != None
+
+    @staticmethod
+    def from_string(s):
+        if not UUID.is_valid_string(s):
+            raise error.Error("%s is not a valid UUID" % s)
+        return UUID(s)
+
+    @staticmethod
+    def from_json(json, symtab=None):
+        try:
+            s = ovs.db.parser.unwrap_json(json, "uuid", unicode)
+            if not UUID.uuidRE.match(s):
+                raise error.Error("\"%s\" is not a valid UUID" % s, json)
+            return UUID(s)
+        except error.Error, e:
+            try:
+                name = ovs.db.parser.unwrap_json(json, "named-uuid", unicode)
+            except error.Error:
+                raise e
+
+            if name not in symtab:
+                symtab[name] = uuid4()
+            return symtab[name]
+
+    def to_json(self):
+        return ["uuid", str(self)]
+
+    def cInitUUID(self, var):
+        m = re.match(str(self))
+        return ["%s.parts[0] = 0x%s;" % (var, m.group(1)),
+                "%s.parts[1] = 0x%s%s;" % (var, m.group(2), m.group(3)),
+                "%s.parts[2] = 0x%s%s;" % (var, m.group(4), m.group(5)),
+                "%s.parts[3] = 0x%s;" % (var, m.group(6))]
+
diff --git a/python/ovs/poller.py b/python/ovs/poller.py
new file mode 100644
index 000000000..57417c481
--- /dev/null
+++ b/python/ovs/poller.py
@@ -0,0 +1,123 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+import logging
+import select
+
+class Poller(object):
+    """High-level wrapper around the "poll" system call.
+
+    Intended usage is for the program's main loop to go about its business
+    servicing whatever events it needs to.  Then, when it runs out of immediate
+    tasks, it calls each subordinate module or object's "wait" function, which
+    in turn calls one (or more) of the functions Poller.fd_wait(),
+    Poller.immediate_wake(), and Poller.timer_wait() to register to be awakened
+    when the appropriate event occurs.  Then the main loop calls
+    Poller.block(), which blocks until one of the registered events happens."""
+
+    def __init__(self):
+        self.__reset()
+
+    def fd_wait(self, fd, events):
+        """Registers 'fd' as waiting for the specified 'events' (which should
+        be select.POLLIN or select.POLLOUT or their bitwise-OR).  The following
+        call to self.block() will wake up when 'fd' becomes ready for one or
+        more of the requested events.
+        
+        The event registration is one-shot: only the following call to
+        self.block() is affected.  The event will need to be re-registered
+        after self.block() is called if it is to persist.
+
+        'fd' may be an integer file descriptor or an object with a fileno()
+        method that returns an integer file descriptor."""
+        self.poll.register(fd, events)
+
+    def __timer_wait(self, msec):
+        if self.timeout < 0 or msec < self.timeout:
+            self.timeout = msec
+
+    def timer_wait(self, msec):
+        """Causes the following call to self.block() to block for no more than
+        'msec' milliseconds.  If 'msec' is nonpositive, the following call to
+        self.block() will not block at all.
+
+        The timer registration is one-shot: only the following call to
+        self.block() is affected.  The timer will need to be re-registered
+        after self.block() is called if it is to persist."""
+        if msec <= 0:
+            self.immediate_wake()
+        else:
+            self.__timer_wait(msec)
+
+    def timer_wait_until(self, msec):
+        """Causes the following call to self.block() to wake up when the
+        current time, as returned by Time.msec(), reaches 'msec' or later.  If
+        'msec' is earlier than the current time, the following call to
+        self.block() will not block at all.
+
+        The timer registration is one-shot: only the following call to
+        self.block() is affected.  The timer will need to be re-registered
+        after self.block() is called if it is to persist."""
+        now = Time.msec()
+        if msec <= now:
+            self.immediate_wake()
+        else:
+            self.__timer_wait(msec - now)
+
+    def immediate_wake(self):
+        """Causes the following call to self.block() to wake up immediately,
+        without blocking."""
+        self.timeout = 0
+
+    def block(self):
+        """Blocks until one or more of the events registered with
+        self.fd_wait() occurs, or until the minimum duration registered with
+        self.timer_wait() elapses, or not at all if self.immediate_wake() has
+        been called."""
+        try:
+            try:
+                events = self.poll.poll(self.timeout)
+                self.__log_wakeup(events)
+            except select.error, e:
+                # XXX rate-limit
+                error, msg = e
+                if error != errno.EINTR:
+                    logging.error("poll: %s" % e[1])
+        finally:
+            self.__reset()
+
+    def __log_wakeup(self, events):
+        if not events:
+            logging.debug("%d-ms timeout" % self.timeout)
+        else:
+            for fd, revents in events:
+                if revents != 0:
+                    s = ""
+                    if revents & select.POLLIN:
+                        s += "[POLLIN]"
+                    if revents & select.POLLOUT:
+                        s += "[POLLOUT]"
+                    if revents & select.POLLERR:
+                        s += "[POLLERR]"
+                    if revents & select.POLLHUP:
+                        s += "[POLLHUP]"
+                    if revents & select.POLLNVAL:
+                        s += "[POLLNVAL]"
+                    logging.debug("%s on fd %d" % (s, fd))
+
+    def __reset(self):
+        self.poll = select.poll()
+        self.timeout = -1            
+
diff --git a/python/ovs/process.py b/python/ovs/process.py
new file mode 100644
index 000000000..094e08533
--- /dev/null
+++ b/python/ovs/process.py
@@ -0,0 +1,39 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import signal
+
+def _signal_status_msg(type, signr):
+    s = "%s by signal %d" % (type, signr)
+    for name in signal.__dict__:
+        if name.startswith("SIG") and signal.__dict__[name] == signr:
+            return "%s (%s)" % (s, name)
+    return s
+    
+def status_msg(status):
+    """Given 'status', which is a process status in the form reported by
+    waitpid(2) and returned by process_status(), returns a string describing
+    how the process terminated."""
+    if os.WIFEXITED(status):
+        s = "exit status %d" % os.WEXITSTATUS(status)
+    elif os.WIFSIGNALED(status):
+        s = _signal_status_msg("killed", os.WTERMSIG(status))
+    elif os.WIFSTOPPED(status):
+        s = _signal_status_msg("stopped", os.WSTOPSIG(status))
+    else:
+        s = "terminated abnormally (%x)" % status
+    if os.WCOREDUMP(status):
+        s += ", core dumped"
+    return s
diff --git a/python/ovs/reconnect.py b/python/ovs/reconnect.py
new file mode 100644
index 000000000..90485799b
--- /dev/null
+++ b/python/ovs/reconnect.py
@@ -0,0 +1,563 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import logging
+import os
+
+# Values returned by Reconnect.run()
+CONNECT = 'connect'
+DISCONNECT = 'disconnect'
+PROBE = 'probe'
+
+EOF = -1
+
+class Reconnect(object):
+    """A finite-state machine for connecting and reconnecting to a network
+    resource with exponential backoff.  It also provides optional support for
+    detecting a connection on which the peer is no longer responding.
+
+    The library does not implement anything networking related, only an FSM for
+    networking code to use.
+
+    Many Reconnect methods take a "now" argument.  This makes testing easier
+    since there is no hidden state.  When not testing, just pass the return
+    value of ovs.time.msec().  (Perhaps this design should be revisited
+    later.)"""
+
+    class Void(object):
+        name = "VOID"
+        is_connected = False
+
+        @staticmethod
+        def deadline(fsm):
+            return None
+
+        @staticmethod
+        def run(fsm, now):
+            return None
+
+    class Listening(object):
+        name = "LISTENING"
+        is_connected = False
+
+        @staticmethod
+        def deadline(fsm):
+            return None
+
+        @staticmethod
+        def run(fsm, now):
+            return None
+
+    class Backoff(object):
+        name = "BACKOFF"
+        is_connected = False
+
+        @staticmethod
+        def deadline(fsm):
+            return fsm.state_entered + fsm.backoff
+
+        @staticmethod
+        def run(fsm, now):
+            return CONNECT
+
+    class ConnectInProgress(object):
+        name = "CONNECT_IN_PROGRESS"
+        is_connected = False
+
+        @staticmethod
+        def deadline(fsm):
+            return fsm.state_entered + max(1000, fsm.backoff)
+
+        @staticmethod
+        def run(fsm, now):
+            return DISCONNECT
+
+    class Active(object):
+        name = "ACTIVE"
+        is_connected = True
+
+        @staticmethod
+        def deadline(fsm):
+            if fsm.probe_interval:
+                base = max(fsm.last_received, fsm.state_entered)
+                return base + fsm.probe_interval
+            return None
+
+        @staticmethod
+        def run(fsm, now):
+            logging.debug("%s: idle %d ms, sending inactivity probe"
+                          % (fsm.name,
+                             now - max(fsm.last_received, fsm.state_entered)))
+            fsm._transition(now, Reconnect.Idle)
+            return PROBE
+
+    class Idle(object):
+        name = "IDLE"
+        is_connected = True
+
+        @staticmethod
+        def deadline(fsm):
+            return fsm.state_entered + fsm.probe_interval
+
+        @staticmethod
+        def run(fsm, now):
+            logging.error("%s: no response to inactivity probe after %.3g "
+                          "seconds, disconnecting"
+                          % (fsm.name, (now - fsm.state_entered) / 1000.0))
+            return DISCONNECT
+
+    class Reconnect:
+        name = "RECONNECT"
+        is_connected = False
+
+        @staticmethod
+        def deadline(fsm):
+            return fsm.state_entered
+
+        @staticmethod
+        def run(fsm, now):
+            return DISCONNECT
+
+    def __init__(self, now):
+        """Creates and returns a new reconnect FSM with default settings.  The
+        FSM is initially disabled.  The caller will likely want to call
+        self.enable() and self.set_name() on the returned object."""
+
+        self.name = "void"
+        self.min_backoff = 1000
+        self.max_backoff = 8000
+        self.probe_interval = 5000
+        self.passive = False
+        self.info_level = logging.info
+
+        self.state = Reconnect.Void
+        self.state_entered = now
+        self.backoff = 0
+        self.last_received = now
+        self.last_connected = now
+        self.max_tries = None
+
+        self.creation_time = now
+        self.n_attempted_connections = 0
+        self.n_successful_connections = 0
+        self.total_connected_duration = 0
+        self.seqno = 0
+
+    def set_quiet(self, quiet):
+        """If 'quiet' is true, this object will log informational messages at
+        debug level, by default keeping them out of log files.  This is
+        appropriate if the connection is one that is expected to be
+        short-lived, so that the log messages are merely distracting.
+        
+        If 'quiet' is false, this object logs informational messages at info
+        level.  This is the default.
+        
+        This setting has no effect on the log level of debugging, warning, or
+        error messages."""
+        if quiet:
+            self.info_level = logging.debug
+        else:
+            self.info_level = logging.info
+
+    def get_name(self):
+        return self.name
+
+    def set_name(self, name):
+        """Sets this object's name to 'name'.  If 'name' is None, then "void"
+        is used instead.
+        
+        The name is used in log messages."""
+        if name is None:
+            self.name = "void"
+        else:
+            self.name = name
+
+    def get_min_backoff(self):
+        """Return the minimum number of milliseconds to back off between
+        consecutive connection attempts.  The default is 1000 ms."""
+        return self.min_backoff
+
+    def get_max_backoff(self):
+        """Return the maximum number of milliseconds to back off between
+        consecutive connection attempts.  The default is 8000 ms."""
+        return self.max_backoff
+
+    def get_probe_interval(self):
+        """Returns the "probe interval" in milliseconds.  If this is zero, it
+        disables the connection keepalive feature.  If it is nonzero, then if
+        the interval passes while the FSM is connected and without
+        self.received() being called, self.run() returns ovs.reconnect.PROBE.
+        If the interval passes again without self.received() being called,
+        self.run() returns ovs.reconnect.DISCONNECT."""
+        return self.probe_interval
+
+    def set_max_tries(self, max_tries):
+        """Limits the maximum number of times that this object will ask the
+        client to try to reconnect to 'max_tries'.  None (the default) means an
+        unlimited number of tries.
+
+        After the number of tries has expired, the FSM will disable itself
+        instead of backing off and retrying."""
+        self.max_tries = max_tries
+
+    def get_max_tries(self):
+        """Returns the current remaining number of connection attempts,
+        None if the number is unlimited."""
+        return self.max_tries
+
+    def set_backoff(self, min_backoff, max_backoff):
+        """Configures the backoff parameters for this FSM.  'min_backoff' is
+        the minimum number of milliseconds, and 'max_backoff' is the maximum,
+        between connection attempts.
+
+        'min_backoff' must be at least 1000, and 'max_backoff' must be greater
+        than or equal to 'min_backoff'."""
+        self.min_backoff = max(min_backoff, 1000)
+        if self.max_backoff:
+            self.max_backoff = max(max_backoff, 1000)
+        else:
+            self.max_backoff = 8000
+        if self.min_backoff > self.max_backoff:
+            self.max_backoff = self.min_backoff
+
+        if (self.state == Reconnect.Backoff and
+            self.backoff > self.max_backoff):
+                self.backoff = self.max_backoff
+        
+    def set_probe_interval(self, probe_interval):
+        """Sets the "probe interval" to 'probe_interval', in milliseconds.  If
+        this is zero, it disables the connection keepalive feature.  If it is
+        nonzero, then if the interval passes while this FSM is connected and
+        without self.received() being called, self.run() returns
+        ovs.reconnect.PROBE.  If the interval passes again without
+        self.received() being called, self.run() returns
+        ovs.reconnect.DISCONNECT.
+
+        If 'probe_interval' is nonzero, then it will be forced to a value of at
+        least 1000 ms."""
+        if probe_interval:
+            self.probe_interval = max(1000, probe_interval)
+        else:
+            self.probe_interval = 0
+
+    def is_passive(self):
+        """Returns true if 'fsm' is in passive mode, false if 'fsm' is in
+        active mode (the default)."""
+        return self.passive
+
+    def set_passive(self, passive, now):
+        """Configures this FSM for active or passive mode.  In active mode (the
+        default), the FSM is attempting to connect to a remote host.  In
+        passive mode, the FSM is listening for connections from a remote host."""
+        if self.passive != passive:
+            self.passive = passive
+
+            if ((passive and self.state in (Reconnect.ConnectInProgress,
+                                            Reconnect.Reconnect)) or
+                (not passive and self.state == Reconnect.Listening
+                 and self.__may_retry())):
+                self._transition(now, Reconnect.Backoff)
+                self.backoff = 0
+
+    def is_enabled(self):
+        """Returns true if this FSM has been enabled with self.enable().
+        Calling another function that indicates a change in connection state,
+        such as self.disconnected() or self.force_reconnect(), will also enable
+        a reconnect FSM."""
+        return self.state != Reconnect.Void
+
+    def enable(self, now):
+        """If this FSM is disabled (the default for newly created FSMs),
+        enables it, so that the next call to reconnect_run() for 'fsm' will
+        return ovs.reconnect.CONNECT.
+
+        If this FSM is not disabled, this function has no effect."""
+        if self.state == Reconnect.Void and self.__may_retry():
+            self._transition(now, Reconnect.Backoff)
+            self.backoff = 0
+
+    def disable(self, now):
+        """Disables this FSM.  Until 'fsm' is enabled again, self.run() will
+        always return 0."""
+        if self.state != Reconnect.Void:
+            self._transition(now, Reconnect.Void)
+
+    def force_reconnect(self, now):
+        """If this FSM is enabled and currently connected (or attempting to
+        connect), forces self.run() to return ovs.reconnect.DISCONNECT the next
+        time it is called, which should cause the client to drop the connection
+        (or attempt), back off, and then reconnect."""
+        if self.state in (Reconnect.ConnectInProgress,
+                          Reconnect.Active,
+                          Reconnect.Idle):
+            self._transition(now, Reconnect.Reconnect)
+
+    def disconnected(self, now, error):
+        """Tell this FSM that the connection dropped or that a connection
+        attempt failed.  'error' specifies the reason: a positive value
+        represents an errno value, EOF indicates that the connection was closed
+        by the peer (e.g. read() returned 0), and 0 indicates no specific
+        error.
+
+        The FSM will back off, then reconnect."""
+        if self.state not in (Reconnect.Backoff, Reconnect.Void):
+            # Report what happened
+            if self.state in (Reconnect.Active, Reconnect.Idle):
+                if error > 0:
+                    logging.warning("%s: connection dropped (%s)"
+                                    % (self.name, os.strerror(error)))
+                elif error == EOF:
+                    self.info_level("%s: connection closed by peer"
+                                    % self.name)
+                else:
+                    self.info_level("%s: connection dropped" % self.name)
+            elif self.state == Reconnect.Listening:
+                if error > 0:
+                    logging.warning("%s: error listening for connections (%s)"
+                                    % (self.name, os.strerror(error)))
+                else:
+                    self.info_level("%s: error listening for connections"
+                                    % self.name)
+            else:
+                if self.passive:
+                    type = "listen"
+                else:
+                    type = "connection"
+                if error > 0:
+                    logging.warning("%s: %s attempt failed (%s)"
+                                    % (self.name, type, os.strerror(error)))
+                else:
+                    self.info_level("%s: %s attempt timed out"
+                                    % (self.name, type))
+
+            # Back off
+            if (self.state in (Reconnect.Active, Reconnect.Idle) and
+                (self.last_received - self.last_connected >= self.backoff or
+                 self.passive)):
+                if self.passive:
+                    self.backoff = 0
+                else:
+                    self.backoff = self.min_backoff
+            else:
+                if self.backoff < self.min_backoff:
+                    self.backoff = self.min_backoff
+                elif self.backoff >= self.max_backoff / 2:
+                    self.backoff = self.max_backoff
+                else:
+                    self.backoff *= 2
+
+                if self.passive:
+                    self.info_level("%s: waiting %.3g seconds before trying "
+                                    "to listen again"
+                                    % (self.name, self.backoff / 1000.0))
+                else:
+                    self.info_level("%s: waiting %.3g seconds before reconnect"
+                                    % (self.name, self.backoff / 1000.0))
+
+            if self.__may_retry():
+                self._transition(now, Reconnect.Backoff)
+            else:
+                self._transition(now, Reconnect.Void)
+
+    def connecting(self, now):
+        """Tell this FSM that a connection or listening attempt is in progress.
+
+        The FSM will start a timer, after which the connection or listening
+        attempt will be aborted (by returning ovs.reconnect.DISCONNECT from
+        self.run())."""
+        if self.state != Reconnect.ConnectInProgress:
+            if self.passive:
+                self.info_level("%s: listening..." % self.name)
+            else:
+                self.info_level("%s: connecting..." % self.name)
+            self._transition(now, Reconnect.ConnectInProgress)
+            
+    def listening(self, now):
+        """Tell this FSM that the client is listening for connection attempts.
+        This state last indefinitely until the client reports some change.
+        
+        The natural progression from this state is for the client to report
+        that a connection has been accepted or is in progress of being
+        accepted, by calling self.connecting() or self.connected().
+        
+        The client may also report that listening failed (e.g. accept()
+        returned an unexpected error such as ENOMEM) by calling
+        self.listen_error(), in which case the FSM will back off and eventually
+        return ovs.reconnect.CONNECT from self.run() to tell the client to try
+        listening again."""
+        if self.state != Reconnect.Listening:
+            self.info_level("%s: listening..." % self.name)
+            self._transition(now, Reconnect.Listening)
+
+    def listen_error(self, now, error):
+        """Tell this FSM that the client's attempt to accept a connection
+        failed (e.g. accept() returned an unexpected error such as ENOMEM).
+        
+        If the FSM is currently listening (self.listening() was called), it
+        will back off and eventually return ovs.reconnect.CONNECT from
+        self.run() to tell the client to try listening again.  If there is an
+        active connection, this will be delayed until that connection drops."""
+        if self.state == Reconnect.Listening:
+            self.disconnected(now, error)
+
+    def connected(self, now):
+        """Tell this FSM that the connection was successful.
+
+        The FSM will start the probe interval timer, which is reset by
+        self.received().  If the timer expires, a probe will be sent (by
+        returning ovs.reconnect.PROBE from self.run().  If the timer expires
+        again without being reset, the connection will be aborted (by returning
+        ovs.reconnect.DISCONNECT from self.run()."""
+        if not self.state.is_connected:
+            self.connecting(now)
+
+            self.info_level("%s: connected" % self.name)
+            self._transition(now, Reconnect.Active)
+            self.last_connected = now
+
+    def connect_failed(self, now, error):
+        """Tell this FSM that the connection attempt failed.
+
+        The FSM will back off and attempt to reconnect."""
+        self.connecting(now)
+        self.disconnected(now, error)
+
+    def received(self, now):
+        """Tell this FSM that some data was received.  This resets the probe
+        interval timer, so that the connection is known not to be idle."""
+        if self.state != Reconnect.Active:
+            self._transition(now, Reconnect.Active)
+        self.last_received = now
+
+    def _transition(self, now, state):
+        if self.state == Reconnect.ConnectInProgress:
+            self.n_attempted_connections += 1
+            if state == Reconnect.Active:
+                self.n_successful_connections += 1
+
+        connected_before = self.state.is_connected
+        connected_now = state.is_connected
+        if connected_before != connected_now:
+            if connected_before:
+                self.total_connected_duration += now - self.last_connected
+            self.seqno += 1
+            
+        logging.debug("%s: entering %s" % (self.name, state.name))
+        self.state = state
+        self.state_entered = now
+
+    def run(self, now):
+        """Assesses whether any action should be taken on this FSM.  The return
+        value is one of:
+        
+            - None: The client need not take any action.
+        
+            - Active client, ovs.reconnect.CONNECT: The client should start a
+              connection attempt and indicate this by calling
+              self.connecting().  If the connection attempt has definitely
+              succeeded, it should call self.connected().  If the connection
+              attempt has definitely failed, it should call
+              self.connect_failed().
+        
+              The FSM is smart enough to back off correctly after successful
+              connections that quickly abort, so it is OK to call
+              self.connected() after a low-level successful connection
+              (e.g. connect()) even if the connection might soon abort due to a
+              failure at a high-level (e.g. SSL negotiation failure).
+        
+            - Passive client, ovs.reconnect.CONNECT: The client should try to
+              listen for a connection, if it is not already listening.  It
+              should call self.listening() if successful, otherwise
+              self.connecting() or reconnected_connect_failed() if the attempt
+              is in progress or definitely failed, respectively.
+        
+              A listening passive client should constantly attempt to accept a
+              new connection and report an accepted connection with
+              self.connected().
+        
+            - ovs.reconnect.DISCONNECT: The client should abort the current
+              connection or connection attempt or listen attempt and call
+              self.disconnected() or self.connect_failed() to indicate it.
+        
+            - ovs.reconnect.PROBE: The client should send some kind of request
+              to the peer that will elicit a response, to ensure that the
+              connection is indeed in working order.  (This will only be
+              returned if the "probe interval" is nonzero--see
+              self.set_probe_interval())."""
+        if now >= self.state.deadline(self):
+            return self.state.run(self, now)
+        else:
+            return None
+        
+    def wait(self, poller, now):
+        """Causes the next call to poller.block() to wake up when self.run()
+        should be called."""
+        timeout = self.timeout(now)
+        if timeout >= 0:
+            poller.timer_wait(timeout)
+
+    def timeout(self, now):
+        """Returns the number of milliseconds after which self.run() should be
+        called if nothing else notable happens in the meantime, or a negative
+        number if this is currently unnecessary."""
+        deadline = self.state.deadline(self)
+        if deadline is not None:
+            remaining = deadline - now
+            return max(0, remaining)
+        else:
+            return None
+
+    def is_connected(self):
+        """Returns True if this FSM is currently believed to be connected, that
+        is, if self.connected() was called more recently than any call to
+        self.connect_failed() or self.disconnected() or self.disable(), and
+        False otherwise."""
+        return self.state.is_connected
+
+    def get_connection_duration(self, now):
+        """Returns the number of milliseconds for which this FSM has been
+        continuously connected to its peer.  (If this FSM is not currently
+        connected, this is 0.)"""
+        if self.is_connected():
+            return now - self.last_connected
+        else:
+            return 0
+
+    def get_stats(self, now):
+        class Stats(object):
+            pass
+        stats = Stats()
+        stats.creation_time = self.creation_time
+        stats.last_connected = self.last_connected
+        stats.last_received = self.last_received
+        stats.backoff = self.backoff
+        stats.seqno = self.seqno
+        stats.is_connected = self.is_connected()
+        stats.current_connection_duration = self.get_connection_duration(now)
+        stats.total_connected_duration = (stats.current_connection_duration +
+                                          self.total_connected_duration)
+        stats.n_attempted_connections = self.n_attempted_connections
+        stats.n_successful_connections = self.n_successful_connections
+        stats.state = self.state.name
+        stats.state_elapsed = now - self.state_entered
+        return stats
+
+    def __may_retry(self):
+        if self.max_tries is None:
+            return True
+        elif self.max_tries > 0:
+            self.max_tries -= 1
+            return True
+        else:
+            return False
diff --git a/python/ovs/socket_util.py b/python/ovs/socket_util.py
new file mode 100644
index 000000000..4f4f60362
--- /dev/null
+++ b/python/ovs/socket_util.py
@@ -0,0 +1,143 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+import logging
+import os
+import select
+import socket
+import sys
+
+import ovs.fatal_signal
+
+def make_unix_socket(style, nonblock, bind_path, connect_path):
+    """Creates a Unix domain socket in the given 'style' (either
+    socket.SOCK_DGRAM or socket.SOCK_STREAM) that is bound to 'bind_path' (if
+    'bind_path' is not None) and connected to 'connect_path' (if 'connect_path'
+    is not None).  If 'nonblock' is true, the socket is made non-blocking.
+
+    Returns (error, socket): on success 'error' is 0 and 'socket' is a new
+    socket object, on failure 'error' is a positive errno value and 'socket' is
+    None."""
+
+    try:
+        sock = socket.socket(socket.AF_UNIX, style)
+    except socket.error, e:
+        return get_exception_errno(e), None
+
+    try:
+        if nonblock:
+            set_nonblocking(sock)
+        if bind_path is not None:
+            # Delete bind_path but ignore ENOENT.
+            try:
+                os.unlink(bind_path)
+            except OSError, e:
+                if e.errno != errno.ENOENT:
+                    return e.errno, None
+
+            ovs.fatal_signal.add_file_to_unlink(bind_path)
+            sock.bind(bind_path)
+
+            try:
+                if sys.hexversion >= 0x02060000:
+                    os.fchmod(sock.fileno(), 0700)
+                else:
+                    os.chmod("/dev/fd/%d" % sock.fileno(), 0700)
+            except OSError, e:
+                pass
+        if connect_path is not None:
+            try:
+                sock.connect(connect_path)
+            except socket.error, e:
+                if get_exception_errno(e) != errno.EINPROGRESS:
+                    raise
+        return 0, sock
+    except socket.error, e:
+        sock.close()
+        try:
+            os.unlink(bind_path)
+        except OSError, e:
+            pass
+        if bind_path is not None:
+            ovs.fatal_signal.add_file_to_unlink(bind_path)
+        return get_exception_errno(e), None
+
+def check_connection_completion(sock):
+    p = select.poll()
+    p.register(sock, select.POLLOUT)
+    if len(p.poll(0)) == 1:
+        return get_socket_error(sock)
+    else:
+        return errno.EAGAIN
+
+def get_socket_error(sock):
+    """Returns the errno value associated with 'socket' (0 if no error) and
+    resets the socket's error status."""
+    return sock.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
+
+def get_exception_errno(e):
+    """A lot of methods on Python socket objects raise socket.error, but that
+    exception is documented as having two completely different forms of
+    arguments: either a string or a (errno, string) tuple.  We only want the
+    errno."""
+    if type(e.args) == tuple:
+        return e.args[0]
+    else:
+        return errno.EPROTO
+
+null_fd = -1
+def get_null_fd():
+    """Returns a readable and writable fd for /dev/null, if successful,
+    otherwise a negative errno value.  The caller must not close the returned
+    fd (because the same fd will be handed out to subsequent callers)."""
+    global null_fd
+    if null_fd < 0:
+        try:
+            null_fd = os.open("/dev/null", os.O_RDWR)
+        except OSError, e:
+            logging.error("could not open /dev/null: %s"
+                          % os.strerror(e.errno))
+            return -e.errno
+    return null_fd
+
+def write_fully(fd, buf):
+    """Returns an (error, bytes_written) tuple where 'error' is 0 on success,
+    otherwise a positive errno value, and 'bytes_written' is the number of
+    bytes that were written before the error occurred.  'error' is 0 if and
+    only if 'bytes_written' is len(buf)."""
+    bytes_written = 0
+    if len(buf) == 0:
+        return 0, 0
+    while True:
+        try:
+            retval = os.write(fd, buf)
+            assert retval >= 0
+            if retval == len(buf):
+                return 0, bytes_written + len(buf)
+            elif retval == 0:
+                logging.warning("write returned 0")
+                return errno.EPROTO, bytes_written
+            else:
+                bytes_written += retval
+                buf = buf[:retval]
+        except OSError, e:
+            return e.errno, bytes_written
+
+def set_nonblocking(sock):
+    try:
+        sock.setblocking(0)
+    except socket.error, e:
+        logging.error("could not set nonblocking mode on socket: %s"
+                      % os.strerror(get_socket_error(e)))
diff --git a/python/ovs/stream.py b/python/ovs/stream.py
new file mode 100644
index 000000000..21923798e
--- /dev/null
+++ b/python/ovs/stream.py
@@ -0,0 +1,316 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+import logging
+import os
+import select
+import socket
+import sys
+
+import ovs.poller
+import ovs.socket_util
+
+class Stream(object):
+    """Bidirectional byte stream.  Currently only Unix domain sockets
+    are implemented."""
+    n_unix_sockets = 0
+
+    # States.
+    __S_CONNECTING = 0
+    __S_CONNECTED = 1
+    __S_DISCONNECTED = 2
+
+    # Kinds of events that one might wait for.
+    W_CONNECT = 0               # Connect complete (success or failure).
+    W_RECV = 1                  # Data received.
+    W_SEND = 2                  # Send buffer room available.
+
+    @staticmethod
+    def is_valid_name(name):
+        """Returns True if 'name' is a stream name in the form "TYPE:ARGS" and
+        TYPE is a supported stream type (currently only "unix:"), otherwise
+        False."""
+        return name.startswith("unix:")
+
+    def __init__(self, socket, name, bind_path, status):
+        self.socket = socket
+        self.name = name
+        self.bind_path = bind_path
+        if status == errno.EAGAIN:
+            self.state = Stream.__S_CONNECTING
+        elif status == 0:
+            self.state = Stream.__S_CONNECTED
+        else:
+            self.state = Stream.__S_DISCONNECTED
+
+        self.error = 0
+
+    @staticmethod
+    def open(name):
+        """Attempts to connect a stream to a remote peer.  'name' is a
+        connection name in the form "TYPE:ARGS", where TYPE is an active stream
+        class's name and ARGS are stream class-specific.  Currently the only
+        supported TYPE is "unix".
+
+        Returns (error, stream): on success 'error' is 0 and 'stream' is the
+        new Stream, on failure 'error' is a positive errno value and 'stream'
+        is None.
+
+        Never returns errno.EAGAIN or errno.EINPROGRESS.  Instead, returns 0
+        and a new Stream.  The connect() method can be used to check for
+        successful connection completion."""
+        if not Stream.is_valid_name(name):
+            return errno.EAFNOSUPPORT, None
+
+        Stream.n_unix_sockets += 1
+        bind_path = "/tmp/stream-unix.%ld.%d" % (os.getpid(),
+                                                 Stream.n_unix_sockets)
+        connect_path = name[5:]
+        error, sock = ovs.socket_util.make_unix_socket(socket.SOCK_STREAM,
+                                                       True, bind_path,
+                                                       connect_path)
+        if error:
+            return error, None
+        else:
+            status = ovs.socket_util.check_connection_completion(sock)
+            return 0, Stream(sock, name, bind_path, status)
+
+    @staticmethod
+    def open_block(tuple):
+        """Blocks until a Stream completes its connection attempt, either
+        succeeding or failing.  'tuple' should be the tuple returned by
+        Stream.open().  Returns a tuple of the same form.
+
+        Typical usage:
+        error, stream = Stream.open_block(Stream.open("tcp:1.2.3.4:5"))"""
+
+        error, stream = tuple
+        if not error:
+            while True:
+                error = stream.connect()
+                if error != errno.EAGAIN:
+                    break
+                stream.run()
+                poller = ovs.poller.Poller()
+                stream.run_wait()
+                stream.connect_wait(poller)
+                poller.block()
+            assert error != errno.EINPROGRESS
+        
+        if error and stream:
+            stream.close()
+            stream = None
+        return error, stream
+
+    def close(self):
+        self.socket.close()
+        if self.bind_path is not None:
+            ovs.fatal_signal.unlink_file_now(self.bind_path)
+            self.bind_path = None
+
+    def __scs_connecting(self):
+        retval = ovs.socket_util.check_connection_completion(self.socket)
+        assert retval != errno.EINPROGRESS
+        if retval == 0:
+            self.state = Stream.__S_CONNECTED
+        elif retval != errno.EAGAIN:
+            self.state = Stream.__S_DISCONNECTED
+            self.error = retval
+
+    def connect(self):
+        """Tries to complete the connection on this stream.  If the connection
+        is complete, returns 0 if the connection was successful or a positive
+        errno value if it failed.  If the connection is still in progress,
+        returns errno.EAGAIN."""
+        last_state = -1         # Always differs from initial self.state
+        while self.state != last_state:
+            if self.state == Stream.__S_CONNECTING:
+                self.__scs_connecting()
+            elif self.state == Stream.__S_CONNECTED:
+                return 0
+            elif self.state == Stream.__S_DISCONNECTED:
+                return self.error
+
+    def recv(self, n):
+        """Tries to receive up to 'n' bytes from this stream.  Returns a
+        (error, string) tuple:
+        
+            - If successful, 'error' is zero and 'string' contains between 1
+              and 'n' bytes of data.
+
+            - On error, 'error' is a positive errno value.
+
+            - If the connection has been closed in the normal fashion or if 'n'
+              is 0, the tuple is (0, "").
+        
+        The recv function will not block waiting for data to arrive.  If no
+        data have been received, it returns (errno.EAGAIN, "") immediately."""
+
+        retval = self.connect()
+        if retval != 0:
+            return (retval, "")
+        elif n == 0:
+            return (0, "")
+
+        try:
+            return (0, self.socket.recv(n))
+        except socket.error, e:
+            return (ovs.socket_util.get_exception_errno(e), "")
+
+    def send(self, buf):
+        """Tries to send 'buf' on this stream.
+
+        If successful, returns the number of bytes sent, between 1 and
+        len(buf).  0 is only a valid return value if len(buf) is 0.
+
+        On error, returns a negative errno value.
+
+        Will not block.  If no bytes can be immediately accepted for
+        transmission, returns -errno.EAGAIN immediately."""
+
+        retval = self.connect()
+        if retval != 0:
+            return -retval
+        elif len(buf) == 0:
+            return 0
+
+        try:
+            return self.socket.send(buf)
+        except socket.error, e:
+            return -ovs.socket_util.get_exception_errno(e)
+
+    def run(self):
+        pass
+
+    def run_wait(self, poller):
+        pass
+
+    def wait(self, poller, wait):
+        assert wait in (Stream.W_CONNECT, Stream.W_RECV, Stream.W_SEND)
+
+        if self.state == Stream.__S_DISCONNECTED:
+            poller.immediate_wake()
+            return
+
+        if self.state == Stream.__S_CONNECTING:
+            wait = Stream.W_CONNECT
+        if wait in (Stream.W_CONNECT, Stream.W_SEND):
+            poller.fd_wait(self.socket, select.POLLOUT)
+        else:
+            poller.fd_wait(self.socket, select.POLLIN)
+
+    def connect_wait(self, poller):
+        self.wait(poller, Stream.W_CONNECT)
+        
+    def recv_wait(self, poller):
+        self.wait(poller, Stream.W_RECV)
+        
+    def send_wait(self, poller):
+        self.wait(poller, Stream.W_SEND)
+        
+    def get_name(self):
+        return self.name
+        
+    def __del__(self):
+        # Don't delete the file: we might have forked.
+        self.socket.close()
+
+class PassiveStream(object):
+    @staticmethod
+    def is_valid_name(name):
+        """Returns True if 'name' is a passive stream name in the form
+        "TYPE:ARGS" and TYPE is a supported passive stream type (currently only
+        "punix:"), otherwise False."""
+        return name.startswith("punix:")
+
+    def __init__(self, sock, name, bind_path):
+        self.name = name
+        self.socket = sock
+        self.bind_path = bind_path
+
+    @staticmethod
+    def open(name):
+        """Attempts to start listening for remote stream connections.  'name'
+        is a connection name in the form "TYPE:ARGS", where TYPE is an passive
+        stream class's name and ARGS are stream class-specific.  Currently the
+        only supported TYPE is "punix".
+
+        Returns (error, pstream): on success 'error' is 0 and 'pstream' is the
+        new PassiveStream, on failure 'error' is a positive errno value and
+        'pstream' is None."""
+        if not PassiveStream.is_valid_name(name):
+            return errno.EAFNOSUPPORT, None
+
+        bind_path = name[6:]
+        error, sock = ovs.socket_util.make_unix_socket(socket.SOCK_STREAM,
+                                                       True, bind_path, None)
+        if error:
+            return error, None
+
+        try:
+            sock.listen(10)
+        except socket.error, e:
+            logging.error("%s: listen: %s" % (name, os.strerror(e.error)))
+            sock.close()
+            return e.error, None
+
+        return 0, PassiveStream(sock, name, bind_path)
+
+    def close(self):
+        """Closes this PassiveStream."""
+        self.socket.close()
+        if self.bind_path is not None:
+            ovs.fatal_signal.unlink_file_now(self.bind_path)
+            self.bind_path = None
+
+    def accept(self):
+        """Tries to accept a new connection on this passive stream.  Returns
+        (error, stream): if successful, 'error' is 0 and 'stream' is the new
+        Stream object, and on failure 'error' is a positive errno value and
+        'stream' is None.
+
+        Will not block waiting for a connection.  If no connection is ready to
+        be accepted, returns (errno.EAGAIN, None) immediately."""
+
+        while True:
+            try:
+                sock, addr = self.socket.accept()
+                ovs.socket_util.set_nonblocking(sock)
+                return 0, Stream(sock, "unix:%s" % addr, None, 0)
+            except socket.error, e:
+                error = ovs.socket_util.get_exception_errno(e)
+                if error != errno.EAGAIN:
+                    # XXX rate-limit
+                    logging.debug("accept: %s" % os.strerror(error))
+                return error, None
+
+    def wait(self, poller):
+        poller.fd_wait(self.socket, select.POLLIN)
+
+    def __del__(self):
+        # Don't delete the file: we might have forked.
+        self.socket.close()
+
+def usage(name, active, passive, bootstrap):
+    print
+    if active:
+        print("Active %s connection methods:" % name)
+        print("  unix:FILE               "
+               "Unix domain socket named FILE");
+
+    if passive:
+        print("Passive %s connection methods:" % name)
+        print("  punix:FILE              "
+              "listen on Unix domain socket FILE")
diff --git a/python/ovs/timeval.py b/python/ovs/timeval.py
new file mode 100644
index 000000000..cd657ddc4
--- /dev/null
+++ b/python/ovs/timeval.py
@@ -0,0 +1,24 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import time
+
+def msec():
+    """Returns the current time, as the amount of time since the epoch, in
+    milliseconds, as a float."""
+    return time.time() * 1000.0
+
+def postfork():
+    # Just a stub for now
+    pass
diff --git a/python/ovs/util.py b/python/ovs/util.py
new file mode 100644
index 000000000..d4460f39a
--- /dev/null
+++ b/python/ovs/util.py
@@ -0,0 +1,43 @@
+# Copyright (c) 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import sys
+
+_argv0 = sys.argv[0]
+PROGRAM_NAME = _argv0[_argv0.rfind('/') + 1:]
+
+def abs_file_name(dir, file_name):
+    """If 'file_name' starts with '/', returns a copy of 'file_name'.
+    Otherwise, returns an absolute path to 'file_name' considering it relative
+    to 'dir', which itself must be absolute.  'dir' may be None or the empty
+    string, in which case the current working directory is used.
+
+    Returns None if 'dir' is null and getcwd() fails.
+
+    This differs from os.path.abspath() in that it will never change the
+    meaning of a file name."""
+    if file_name.startswith('/'):
+        return file_name
+    else:
+        if dir is None or dir == "":
+            try:
+                dir = os.getcwd()
+            except OSError:
+                return None
+
+        if dir.endswith('/'):
+            return dir + file_name
+        else:
+            return "%s/%s" % (dir, file_name)
diff --git a/tests/atlocal.in b/tests/atlocal.in
index 8ac4f676b..f1c045766 100644
--- a/tests/atlocal.in
+++ b/tests/atlocal.in
@@ -3,3 +3,6 @@ HAVE_OPENSSL='@HAVE_OPENSSL@'
 HAVE_PYTHON='@HAVE_PYTHON@'
 PERL='@PERL@'
 PYTHON='@PYTHON@'
+
+PYTHONPATH=$PYTHONPATH:$abs_top_srcdir/python
+export PYTHONPATH
diff --git a/tests/automake.mk b/tests/automake.mk
index 9a248feb9..e647bbb99 100644
--- a/tests/automake.mk
+++ b/tests/automake.mk
@@ -11,12 +11,14 @@ TESTSUITE_AT = \
 	tests/classifier.at \
 	tests/check-structs.at \
 	tests/daemon.at \
+	tests/daemon-py.at \
 	tests/vconn.at \
 	tests/dir_name.at \
 	tests/aes128.at \
 	tests/uuid.at \
 	tests/json.at \
 	tests/jsonrpc.at \
+	tests/jsonrpc-py.at \
 	tests/timeval.at \
 	tests/lockfile.at \
 	tests/reconnect.at \
@@ -38,6 +40,7 @@ TESTSUITE_AT = \
 	tests/ovsdb-server.at \
 	tests/ovsdb-monitor.at \
 	tests/ovsdb-idl.at \
+	tests/ovsdb-idl-py.at \
 	tests/ovs-vsctl.at \
 	tests/interface-reconfigure.at
 TESTSUITE = $(srcdir)/tests/testsuite
@@ -263,3 +266,11 @@ EXTRA_DIST += \
 	tests/testpki-privkey2.pem \
 	tests/testpki-req.pem \
 	tests/testpki-req2.pem
+
+# Python tests.
+EXTRA_DIST += \
+	tests/test-daemon.py \
+	tests/test-json.py \
+	tests/test-jsonrpc.py \
+	tests/test-ovsdb.py \
+	tests/test-reconnect.py
diff --git a/tests/daemon-py.at b/tests/daemon-py.at
new file mode 100644
index 000000000..7ff376eb7
--- /dev/null
+++ b/tests/daemon-py.at
@@ -0,0 +1,185 @@
+AT_BANNER([daemon unit tests - Python])
+
+AT_SETUP([daemon - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CAPTURE_FILE([pid])
+AT_CAPTURE_FILE([expected])
+# Start the daemon and wait for the pidfile to get created
+# and that its contents are the correct pid.
+AT_CHECK([$PYTHON $srcdir/test-daemon.py --pidfile-name=$PWD/pid& echo $! > expected], [0], [ignore], [ignore])
+OVS_WAIT_UNTIL([test -s pid], [kill `cat expected`])
+AT_CHECK(
+  [pid=`cat pid` && expected=`cat expected` && test "$pid" = "$expected"],
+  [0], [], [], [kill `cat expected`])
+AT_CHECK([kill -0 `cat pid`], [0], [], [], [kill `cat expected`])
+# Kill the daemon and make sure that the pidfile gets deleted.
+kill `cat expected`
+OVS_WAIT_WHILE([kill -0 `cat expected`])
+AT_CHECK([test ! -e pid])
+AT_CLEANUP
+
+AT_SETUP([daemon --monitor - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CAPTURE_FILE([pid])
+AT_CAPTURE_FILE([parent])
+AT_CAPTURE_FILE([parentpid])
+AT_CAPTURE_FILE([newpid])
+# Start the daemon and wait for the pidfile to get created.
+AT_CHECK([$PYTHON $srcdir/test-daemon.py --pidfile-name=$PWD/pid --monitor& echo $! > parent], [0], [ignore], [ignore])
+OVS_WAIT_UNTIL([test -s pid], [kill `cat parent`])
+# Check that the pidfile names a running process,
+# and that the parent process of that process is our child process.
+AT_CHECK([kill -0 `cat pid`], [0], [], [], [kill `cat parent`])
+AT_CHECK([ps -o ppid= -p `cat pid` > parentpid],
+  [0], [], [], [kill `cat parent`])
+AT_CHECK(
+  [parentpid=`cat parentpid` && 
+   parent=`cat parent` && 
+   test $parentpid = $parent],
+  [0], [], [], [kill `cat parent`])
+# Kill the daemon process, making it look like a segfault,
+# and wait for a new child process to get spawned.
+AT_CHECK([cp pid oldpid], [0], [], [], [kill `cat parent`])
+AT_CHECK([kill -SEGV `cat pid`], [0], [], [ignore], [kill `cat parent`])
+OVS_WAIT_WHILE([kill -0 `cat oldpid`], [kill `cat parent`])
+OVS_WAIT_UNTIL([test -s pid && test `cat pid` != `cat oldpid`],
+  [kill `cat parent`])
+AT_CHECK([cp pid newpid], [0], [], [], [kill `cat parent`])
+# Check that the pidfile names a running process,
+# and that the parent process of that process is our child process.
+AT_CHECK([ps -o ppid= -p `cat pid` > parentpid],
+  [0], [], [], [kill `cat parent`])
+AT_CHECK(
+  [parentpid=`cat parentpid` && 
+   parent=`cat parent` && 
+   test $parentpid = $parent],
+  [0], [], [], [kill `cat parent`])
+# Kill the daemon process with SIGTERM, and wait for the daemon
+# and the monitor processes to go away and the pidfile to get deleted.
+AT_CHECK([kill `cat pid`], [0], [], [ignore], [kill `cat parent`])
+OVS_WAIT_WHILE([kill -0 `cat parent` || kill -0 `cat newpid` || test -e pid],
+  [kill `cat parent`])
+AT_CLEANUP
+
+AT_SETUP([daemon --detach - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CAPTURE_FILE([pid])
+# Start the daemon and make sure that the pidfile exists immediately.
+# We don't wait for the pidfile to get created because the daemon is
+# supposed to do so before the parent exits.
+AT_CHECK([$PYTHON $srcdir/test-daemon.py --pidfile-name=$PWD/pid --detach], [0], [ignore], [ignore])
+AT_CHECK([test -s pid])
+AT_CHECK([kill -0 `cat pid`])
+# Kill the daemon and make sure that the pidfile gets deleted.
+cp pid saved-pid
+kill `cat pid`
+OVS_WAIT_WHILE([kill -0 `cat saved-pid`])
+AT_CHECK([test ! -e pid])
+AT_CLEANUP
+
+AT_SETUP([daemon --detach --monitor - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+m4_define([CHECK], 
+  [AT_CHECK([$1], [$2], [$3], [$4], [kill `cat daemon monitor`])])
+AT_CAPTURE_FILE([daemon])
+AT_CAPTURE_FILE([olddaemon])
+AT_CAPTURE_FILE([newdaemon])
+AT_CAPTURE_FILE([monitor])
+AT_CAPTURE_FILE([newmonitor])
+AT_CAPTURE_FILE([init])
+# Start the daemon and make sure that the pidfile exists immediately.
+# We don't wait for the pidfile to get created because the daemon is
+# supposed to do so before the parent exits.
+AT_CHECK([$PYTHON $srcdir/test-daemon.py --pidfile-name=$PWD/daemon --detach --monitor], [0], [ignore], [ignore])
+AT_CHECK([test -s daemon])
+# Check that the pidfile names a running process,
+# and that the parent process of that process is a running process,
+# and that the parent process of that process is init.
+CHECK([kill -0 `cat daemon`])
+CHECK([ps -o ppid= -p `cat daemon` > monitor])
+CHECK([kill -0 `cat monitor`])
+CHECK([ps -o ppid= -p `cat monitor` > init])
+CHECK([test `cat init` = 1])
+# Kill the daemon process, making it look like a segfault,
+# and wait for a new daemon process to get spawned.
+CHECK([cp daemon olddaemon])
+CHECK([kill -SEGV `cat daemon`], [0], [ignore], [ignore])
+OVS_WAIT_WHILE([kill -0 `cat olddaemon`], [kill `cat olddaemon daemon`])
+OVS_WAIT_UNTIL([test -s daemon && test `cat daemon` != `cat olddaemon`],
+  [kill `cat olddaemon daemon`])
+CHECK([cp daemon newdaemon])
+# Check that the pidfile names a running process,
+# and that the parent process of that process is our child process.
+CHECK([kill -0 `cat daemon`])
+CHECK([diff olddaemon newdaemon], [1], [ignore])
+CHECK([ps -o ppid= -p `cat daemon` > newmonitor])
+CHECK([diff monitor newmonitor])
+CHECK([kill -0 `cat newmonitor`])
+CHECK([ps -o ppid= -p `cat newmonitor` > init])
+CHECK([test `cat init` = 1])
+# Kill the daemon process with SIGTERM, and wait for the daemon
+# and the monitor processes to go away and the pidfile to get deleted.
+CHECK([kill `cat daemon`], [0], [], [ignore])
+OVS_WAIT_WHILE(
+  [kill -0 `cat monitor` || kill -0 `cat newdaemon` || test -e daemon],
+  [kill `cat monitor newdaemon`])
+m4_undefine([CHECK])
+AT_CLEANUP
+
+AT_SETUP([daemon --detach startup errors - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CAPTURE_FILE([pid])
+AT_CHECK([$PYTHON $srcdir/test-daemon.py --pidfile-name=$PWD/pid --detach --bail], [1], [], [stderr])
+AT_CHECK([grep 'test-daemon.py: exiting after daemonize_start() as requested' stderr],
+  [0], [ignore], [])
+AT_CHECK([test ! -s pid])
+AT_CLEANUP
+
+AT_SETUP([daemon --detach --monitor startup errors - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CAPTURE_FILE([pid])
+AT_CHECK([$PYTHON $srcdir/test-daemon.py --pidfile-name=$PWD/pid --detach --monitor --bail], [1], [], [stderr])
+AT_CHECK([grep 'test-daemon.py: exiting after daemonize_start() as requested' stderr],
+  [0], [ignore], [])
+AT_CHECK([test ! -s pid])
+AT_CLEANUP
+
+AT_SETUP([daemon --detach closes standard fds - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CAPTURE_FILE([pid])
+AT_CAPTURE_FILE([status])
+AT_CAPTURE_FILE([stderr])
+AT_CHECK([(yes 2>stderr; echo $? > status) | $PYTHON $srcdir/test-daemon.py --pidfile-name=$PWD/pid --detach], [0], [], [])
+AT_CHECK([kill `cat pid`])
+AT_CHECK([test -s status])
+if grep '[[bB]]roken pipe' stderr >/dev/null 2>&1; then
+  # Something in the environment caused SIGPIPE to be ignored, but
+  # 'yes' at least told us that it got EPIPE.  Good enough; we know
+  # that stdout was closed.
+  :
+else
+  # Otherwise make sure that 'yes' died from SIGPIPE.
+  AT_CHECK([kill -l `cat status`], [0], [PIPE
+])
+fi
+AT_CLEANUP
+
+AT_SETUP([daemon --detach --monitor closes standard fds])
+AT_CAPTURE_FILE([pid])
+AT_CAPTURE_FILE([status])
+AT_CAPTURE_FILE([stderr])
+OVSDB_INIT([db])
+AT_CHECK([(yes 2>stderr; echo $? > status) | $PYTHON $srcdir/test-daemon.py --pidfile-name=$PWD/pid --detach], [0], [], [])
+AT_CHECK([kill `cat pid`])
+AT_CHECK([test -s status])
+if grep '[[bB]]roken pipe' stderr >/dev/null 2>&1; then
+  # Something in the environment caused SIGPIPE to be ignored, but
+  # 'yes' at least told us that it got EPIPE.  Good enough; we know
+  # that stdout was closed.
+  :
+else
+  # Otherwise make sure that 'yes' died from SIGPIPE.
+  AT_CHECK([kill -l `cat status`], [0], [PIPE
+])
+fi
+AT_CLEANUP
diff --git a/tests/daemon.at b/tests/daemon.at
index 06f1e6125..d3708637f 100644
--- a/tests/daemon.at
+++ b/tests/daemon.at
@@ -1,4 +1,4 @@
-AT_BANNER([daemon unit tests])
+AT_BANNER([daemon unit tests - C])
 
 AT_SETUP([daemon])
 AT_SKIP_IF([test "$CHECK_LCOV" = true]) # lcov wrapper make pids differ
diff --git a/tests/json.at b/tests/json.at
index af53d76f4..56329ed25 100644
--- a/tests/json.at
+++ b/tests/json.at
@@ -1,4 +1,4 @@
-m4_define([JSON_CHECK_POSITIVE], 
+m4_define([JSON_CHECK_POSITIVE_C], 
   [AT_SETUP([$1])
    AT_KEYWORDS([json positive])
    AT_CHECK([printf %s "AS_ESCAPE([$2])" > input])
@@ -8,7 +8,22 @@ m4_define([JSON_CHECK_POSITIVE],
 ])
    AT_CLEANUP])
 
-m4_define([JSON_CHECK_NEGATIVE], 
+m4_define([JSON_CHECK_POSITIVE_PY], 
+  [AT_SETUP([$1])
+   AT_KEYWORDS([json positive Python])
+   AT_SKIP_IF([test $HAVE_PYTHON = no])
+   AT_CHECK([printf %s "AS_ESCAPE([$2])" > input])
+   AT_CAPTURE_FILE([input])
+   AT_CHECK([$PYTHON $srcdir/test-json.py $4 input], [0], [stdout], [])
+   AT_CHECK([cat stdout], [0], [$3
+])
+   AT_CLEANUP])
+
+m4_define([JSON_CHECK_POSITIVE],
+  [JSON_CHECK_POSITIVE_C([$1 - C], [$2], [$3], [$4])
+   JSON_CHECK_POSITIVE_PY([$1 - Python], [$2], [$3], [$4])])
+
+m4_define([JSON_CHECK_NEGATIVE_C],
   [AT_SETUP([$1])
    AT_KEYWORDS([json negative])
    AT_CHECK([printf %s "AS_ESCAPE([$2])" > input])
@@ -18,6 +33,21 @@ m4_define([JSON_CHECK_NEGATIVE],
 ])
    AT_CLEANUP])
 
+m4_define([JSON_CHECK_NEGATIVE_PY], 
+  [AT_SETUP([$1])
+   AT_KEYWORDS([json negative Python])
+   AT_SKIP_IF([test $HAVE_PYTHON = no])
+   AT_CHECK([printf %s "AS_ESCAPE([$2])" > input])
+   AT_CAPTURE_FILE([input])
+   AT_CHECK([$PYTHON $srcdir/test-json.py $4 input], [1], [stdout], [])
+   AT_CHECK([[sed 's/^error: [^:]*:/error:/' < stdout]], [0], [$3
+])
+   AT_CLEANUP])
+
+m4_define([JSON_CHECK_NEGATIVE],
+  [JSON_CHECK_NEGATIVE_C([$1 - C], [$2], [$3], [$4])
+   JSON_CHECK_NEGATIVE_PY([$1 - Python], [$2], [$3], [$4])])
+
 AT_BANNER([JSON -- arrays])
 
 JSON_CHECK_POSITIVE([empty array], [[ [   ] ]], [[[]]])
@@ -76,13 +106,22 @@ JSON_CHECK_NEGATIVE([null bytes not allowed],
                     [[["\u0000"]]], 
                     [error: null bytes not supported in quoted strings])
 
-AT_SETUP([end of input in quoted string])
+AT_SETUP([end of input in quoted string - C])
 AT_KEYWORDS([json negative])
 AT_CHECK([printf '"xxx' | test-json -], [1],
   [error: line 0, column 4, byte 4: unexpected end of input in quoted string
 ])
 AT_CLEANUP
 
+AT_SETUP([end of input in quoted string - Python])
+AT_KEYWORDS([json negative Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CHECK([printf '"xxx' > input
+$PYTHON $srcdir/test-json.py input], [1],
+  [error: line 0, column 4, byte 4: unexpected end of input in quoted string
+])
+AT_CLEANUP
+
 AT_BANNER([JSON -- objects])
 
 JSON_CHECK_POSITIVE([empty object], [[{ }]], [[{}]])
diff --git a/tests/jsonrpc-py.at b/tests/jsonrpc-py.at
new file mode 100644
index 000000000..e8a98bbce
--- /dev/null
+++ b/tests/jsonrpc-py.at
@@ -0,0 +1,48 @@
+AT_BANNER([JSON-RPC - Python])
+
+AT_SETUP([JSON-RPC request and successful reply - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CHECK([$PYTHON $srcdir/test-jsonrpc.py --detach --pidfile-name=$PWD/pid listen punix:socket])
+AT_CHECK([test -s pid])
+AT_CHECK([kill -0 `cat pid`])
+AT_CHECK(
+  [[$PYTHON $srcdir/test-jsonrpc.py request unix:socket echo '[{"a": "b", "x": null}]']], [0],
+  [[{"error":null,"id":0,"result":[{"a":"b","x":null}]}
+]], [ignore], [test ! -e pid || kill `cat pid`])
+AT_CHECK([kill `cat pid`])
+AT_CLEANUP
+
+AT_SETUP([JSON-RPC request and error reply - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CHECK([$PYTHON $srcdir/test-jsonrpc.py --detach --pidfile-name=$PWD/pid listen punix:socket])
+AT_CHECK([test -s pid])
+AT_CHECK([kill -0 `cat pid`])
+AT_CHECK(
+  [[$PYTHON $srcdir/test-jsonrpc.py request unix:socket bad-request '[]']], [0],
+  [[{"error":{"error":"unknown method"},"id":0,"result":null}
+]], [ignore], [test ! -e pid || kill `cat pid`])
+AT_CHECK([kill `cat pid`])
+AT_CLEANUP
+
+AT_SETUP([JSON-RPC notification - Python])
+AT_SKIP_IF([test $HAVE_PYTHON = no])
+AT_CHECK([$PYTHON $srcdir/test-jsonrpc.py --detach --pidfile-name=$PWD/pid listen punix:socket])
+AT_CHECK([test -s pid])
+# When a daemon dies it deletes its pidfile, so make a copy.
+AT_CHECK([cp pid pid2])
+AT_CHECK([kill -0 `cat pid2`])
+AT_CHECK([[$PYTHON $srcdir/test-jsonrpc.py notify unix:socket shutdown '[]']], [0], [], 
+  [ignore], [kill `cat pid2`])
+AT_CHECK(
+  [pid=`cat pid2`
+   # First try a quick sleep, so that the test completes very quickly
+   # in the normal case.  POSIX doesn't require fractional times to
+   # work, so this might not work.
+   sleep 0.1; if kill -0 $pid; then :; else echo success; exit 0; fi
+   # Then wait up to 2 seconds.
+   sleep 1; if kill -0 $pid; then :; else echo success; exit 0; fi
+   sleep 1; if kill -0 $pid; then :; else echo success; exit 0; fi
+   echo failure; exit 1], [0], [success
+], [ignore])
+AT_CHECK([test ! -e pid])
+AT_CLEANUP
diff --git a/tests/jsonrpc.at b/tests/jsonrpc.at
index 83410f990..856fa46ee 100644
--- a/tests/jsonrpc.at
+++ b/tests/jsonrpc.at
@@ -1,4 +1,4 @@
-AT_BANNER([JSON-RPC])
+AT_BANNER([JSON-RPC - C])
 
 AT_SETUP([JSON-RPC request and successful reply])
 AT_CHECK([test-jsonrpc --detach --pidfile=$PWD/pid listen punix:socket])
diff --git a/tests/ovsdb-column.at b/tests/ovsdb-column.at
index 7dd55e413..b8d093991 100644
--- a/tests/ovsdb-column.at
+++ b/tests/ovsdb-column.at
@@ -1,13 +1,13 @@
 AT_BANNER([OVSDB -- columns])
 
-OVSDB_CHECK_POSITIVE([ordinary column],
+OVSDB_CHECK_POSITIVE_CPY([ordinary column],
   [[parse-column mycol '{"type": "integer"}']],
   [[{"type":"integer"}]])
 
-OVSDB_CHECK_POSITIVE([immutable column],
+OVSDB_CHECK_POSITIVE_CPY([immutable column],
   [[parse-column mycol '{"type": "real", "mutable": false}']],
   [[{"mutable":false,"type":"real"}]])
 
-OVSDB_CHECK_POSITIVE([ephemeral column],
+OVSDB_CHECK_POSITIVE_CPY([ephemeral column],
   [[parse-column mycol '{"type": "uuid", "ephemeral": true}']],
   [[{"ephemeral":true,"type":"uuid"}]])
diff --git a/tests/ovsdb-data.at b/tests/ovsdb-data.at
index ac0f0b7be..98e810837 100644
--- a/tests/ovsdb-data.at
+++ b/tests/ovsdb-data.at
@@ -1,6 +1,6 @@
 AT_BANNER([OVSDB -- default values])
 
-OVSDB_CHECK_POSITIVE([default atoms],
+OVSDB_CHECK_POSITIVE_CPY([default atoms],
   [default-atoms],
   [[integer: OK
 real: OK
@@ -8,7 +8,7 @@ boolean: OK
 string: OK
 uuid: OK]])
 
-OVSDB_CHECK_POSITIVE([default data],
+OVSDB_CHECK_POSITIVE_CPY([default data],
   [default-data],
   [[key integer, value void, n_min 0: OK
 key integer, value integer, n_min 0: OK
@@ -73,7 +73,7 @@ key uuid, value uuid, n_min 1: OK]])
 
 AT_BANNER([OVSDB -- atoms without constraints])
 
-OVSDB_CHECK_POSITIVE([integer atom from JSON], 
+OVSDB_CHECK_POSITIVE_CPY([integer atom from JSON], 
   [[parse-atoms '["integer"]' \
     '[0]' \
     '[-1]' \
@@ -99,7 +99,7 @@ OVSDB_CHECK_POSITIVE([integer atom from string],
 9223372036854775807
 -9223372036854775808])
 
-OVSDB_CHECK_POSITIVE([real atom from JSON], 
+OVSDB_CHECK_POSITIVE_CPY([real atom from JSON], 
   [[parse-atoms '["real"]' \
     '[0]' \
     '[0.0]' \
@@ -133,7 +133,7 @@ OVSDB_CHECK_POSITIVE([real atom from string],
 1e+37
 0.00390625])
 
-OVSDB_CHECK_POSITIVE([boolean atom from JSON],
+OVSDB_CHECK_POSITIVE_CPY([boolean atom from JSON],
   [[parse-atoms '["boolean"]' '[true]' '[false]' ]],
   [true
 false])
@@ -143,7 +143,7 @@ OVSDB_CHECK_POSITIVE([boolean atom from string],
   [true
 false])
 
-OVSDB_CHECK_POSITIVE([string atom from JSON],
+OVSDB_CHECK_POSITIVE_CPY([string atom from JSON],
   [[parse-atoms '["string"]' '[""]' '["true"]' '["\"\\\/\b\f\n\r\t"]']],
   [""
 "true"
@@ -164,7 +164,7 @@ quoted-string
 "true"
 "\"\\/\b\f\n\r\t"])
 
-OVSDB_CHECK_POSITIVE([uuid atom from JSON],
+OVSDB_CHECK_POSITIVE_CPY([uuid atom from JSON],
   [[parse-atoms '["uuid"]' '["uuid", "550e8400-e29b-41d4-a716-446655440000"]']],
   [[["uuid","550e8400-e29b-41d4-a716-446655440000"]]])
 
@@ -172,23 +172,23 @@ OVSDB_CHECK_POSITIVE([uuid atom from string],
   [[parse-atom-strings '["uuid"]' '550e8400-e29b-41d4-a716-446655440000']],
   [550e8400-e29b-41d4-a716-446655440000])
 
-OVSDB_CHECK_POSITIVE([integer atom sorting],
+OVSDB_CHECK_POSITIVE_CPY([integer atom sorting],
   [[sort-atoms '["integer"]' '[55,0,-1,2,1]']],
   [[[-1,0,1,2,55]]])
 
-OVSDB_CHECK_POSITIVE([real atom sorting],
+OVSDB_CHECK_POSITIVE_CPY([real atom sorting],
   [[sort-atoms '["real"]' '[1.25,1.23,0.0,-0.0,-1e99]']],
   [[[-1e+99,0,0,1.23,1.25]]])
 
-OVSDB_CHECK_POSITIVE([boolean atom sorting],
+OVSDB_CHECK_POSITIVE_CPY([boolean atom sorting],
   [[sort-atoms '["boolean"]' '[true,false,true,false,false]']],
   [[[false,false,false,true,true]]])
 
-OVSDB_CHECK_POSITIVE([string atom sorting],
+OVSDB_CHECK_POSITIVE_CPY([string atom sorting],
   [[sort-atoms '["string"]' '["abd","abc","\b","xxx"]']],
   [[["\b","abc","abd","xxx"]]])
 
-OVSDB_CHECK_POSITIVE([uuid atom sorting],
+OVSDB_CHECK_POSITIVE_CPY([uuid atom sorting],
   [[sort-atoms '["uuid"]' '[
     ["uuid", "00000000-0000-0000-0000-000000000001"],
     ["uuid", "00000000-1000-0000-0000-000000000000"],
@@ -225,25 +225,26 @@ OVSDB_CHECK_POSITIVE([uuid atom sorting],
     ["uuid", "00001000-0000-0000-0000-000000000000"]]']],
   [[[["uuid","00000000-0000-0000-0000-000000000000"],["uuid","00000000-0000-0000-0000-000000000001"],["uuid","00000000-0000-0000-0000-000000000010"],["uuid","00000000-0000-0000-0000-000000000100"],["uuid","00000000-0000-0000-0000-000000001000"],["uuid","00000000-0000-0000-0000-000000010000"],["uuid","00000000-0000-0000-0000-000000100000"],["uuid","00000000-0000-0000-0000-000001000000"],["uuid","00000000-0000-0000-0000-000010000000"],["uuid","00000000-0000-0000-0000-000100000000"],["uuid","00000000-0000-0000-0000-001000000000"],["uuid","00000000-0000-0000-0000-010000000000"],["uuid","00000000-0000-0000-0000-100000000000"],["uuid","00000000-0000-0000-0001-000000000000"],["uuid","00000000-0000-0000-0010-000000000000"],["uuid","00000000-0000-0000-0100-000000000000"],["uuid","00000000-0000-0000-1000-000000000000"],["uuid","00000000-0000-0001-0000-000000000000"],["uuid","00000000-0000-0010-0000-000000000000"],["uuid","00000000-0000-0100-0000-000000000000"],["uuid","00000000-0000-1000-0000-000000000000"],["uuid","00000000-0001-0000-0000-000000000000"],["uuid","00000000-0010-0000-0000-000000000000"],["uuid","00000000-0100-0000-0000-000000000000"],["uuid","00000000-1000-0000-0000-000000000000"],["uuid","00000001-0000-0000-0000-000000000000"],["uuid","00000010-0000-0000-0000-000000000000"],["uuid","00000100-0000-0000-0000-000000000000"],["uuid","00001000-0000-0000-0000-000000000000"],["uuid","00010000-0000-0000-0000-000000000000"],["uuid","00100000-0000-0000-0000-000000000000"],["uuid","01000000-0000-0000-0000-000000000000"],["uuid","10000000-0000-0000-0000-000000000000"]]]])
 
-OVSDB_CHECK_POSITIVE([real not acceptable integer JSON atom],
+OVSDB_CHECK_POSITIVE_CPY([real not acceptable integer JSON atom],
   [[parse-atoms '["integer"]' '[0.5]' ]],
   [syntax "0.5": syntax error: expected integer])
 
 dnl <C0> is not allowed anywhere in a UTF-8 string.
 dnl <ED A0 80> is a surrogate and not allowed in UTF-8.
-OVSDB_CHECK_POSITIVE([no invalid UTF-8 sequences in strings],
+OVSDB_CHECK_POSITIVE_CPY([no invalid UTF-8 sequences in strings],
   [parse-atoms '[["string"]]' \
      '@<:@"m4_esyscmd([printf "\300"])"@:>@' \
      '@<:@"m4_esyscmd([printf "\355\240\200"])"@:>@' \
 ],
   [constraint violation: "m4_esyscmd([printf "\300"])" is not a valid UTF-8 string: invalid UTF-8 sequence 0xc0
-constraint violation: "m4_esyscmd([printf "\355\240\200"])" is not a valid UTF-8 string: invalid UTF-8 sequence 0xed 0xa0])
+constraint violation: "m4_esyscmd([printf "\355\240\200"])" is not a valid UTF-8 string: invalid UTF-8 sequence 0xed 0xa0],
+  [], [], [xfail])
 
 OVSDB_CHECK_NEGATIVE([real not acceptable integer string atom],
   [[parse-atom-strings '["integer"]' '0.5' ]],
   ["0.5" is not a valid integer])
 
-OVSDB_CHECK_POSITIVE([string "true" not acceptable boolean JSON atom],
+OVSDB_CHECK_POSITIVE_CPY([string "true" not acceptable boolean JSON atom],
   [[parse-atoms '["boolean"]' '["true"]' ]],
   [syntax ""true"": syntax error: expected boolean])
 
@@ -251,11 +252,11 @@ OVSDB_CHECK_NEGATIVE([string "true" not acceptable boolean string atom],
   [[parse-atom-strings '["boolean"]' '"true"' ]],
   [""true"" is not a valid boolean (use "true" or "false")])
 
-OVSDB_CHECK_POSITIVE([integer not acceptable string JSON atom],
+OVSDB_CHECK_POSITIVE_CPY([integer not acceptable string JSON atom],
   [[parse-atoms '["string"]' '[1]']],
   [syntax "1": syntax error: expected string])
 
-OVSDB_CHECK_POSITIVE([uuid atom must be expressed as JSON array],
+OVSDB_CHECK_POSITIVE_CPY([uuid atom must be expressed as JSON array],
   [[parse-atoms '["uuid"]' '["550e8400-e29b-41d4-a716-446655440000"]']],
   [[syntax ""550e8400-e29b-41d4-a716-446655440000"": syntax error: expected ["uuid", <string>]]])
 
@@ -273,7 +274,7 @@ OVSDB_CHECK_NEGATIVE([uuids must be valid],
 
 AT_BANNER([OVSDB -- atoms with enum constraints])
 
-OVSDB_CHECK_POSITIVE([integer atom enum], 
+OVSDB_CHECK_POSITIVE_CPY([integer atom enum], 
   [[parse-atoms '[{"type": "integer", "enum": ["set", [1, 6, 8, 10]]}]' \
     '[0]' \
     '[1]' \
@@ -296,7 +297,7 @@ constraint violation: 9 is not one of the allowed values ([1, 6, 8, 10])
 10
 constraint violation: 11 is not one of the allowed values ([1, 6, 8, 10])]])
 
-OVSDB_CHECK_POSITIVE([real atom enum], 
+OVSDB_CHECK_POSITIVE_CPY([real atom enum], 
   [[parse-atoms '[{"type": "real", "enum": ["set", [-1.5, 1.5]]}]' \
     '[-2]' \
     '[-1]' \
@@ -313,14 +314,14 @@ constraint violation: 1 is not one of the allowed values ([-1.5, 1.5])
 1.5
 constraint violation: 2 is not one of the allowed values ([-1.5, 1.5])]])
 
-OVSDB_CHECK_POSITIVE([boolean atom enum], 
+OVSDB_CHECK_POSITIVE_CPY([boolean atom enum], 
   [[parse-atoms '[{"type": "boolean", "enum": false}]' \
     '[false]' \
     '[true]']], 
   [[false
 constraint violation: true is not one of the allowed values ([false])]])
 
-OVSDB_CHECK_POSITIVE([string atom enum], 
+OVSDB_CHECK_POSITIVE_CPY([string atom enum], 
   [[parse-atoms '[{"type": "string", "enum": ["set", ["abc", "def"]]}]' \
     '[""]' \
     '["ab"]' \
@@ -335,7 +336,7 @@ constraint violation: ab is not one of the allowed values ([abc, def])
 constraint violation: defg is not one of the allowed values ([abc, def])
 constraint violation: DEF is not one of the allowed values ([abc, def])]])
 
-OVSDB_CHECK_POSITIVE([uuid atom enum], 
+OVSDB_CHECK_POSITIVE_CPY([uuid atom enum], 
   [[parse-atoms '[{"type": "uuid", "enum": ["set", [["uuid", "6d53a6dd-2da7-4924-9927-97f613812382"], ["uuid", "52cbc842-137a-4db5-804f-9f34106a0ba3"]]]}]' \
     '["uuid", "6d53a6dd-2da7-4924-9927-97f613812382"]' \
     '["uuid", "52cbc842-137a-4db5-804f-9f34106a0ba3"]' \
@@ -346,7 +347,7 @@ constraint violation: dab2a6b2-6094-4f43-a7ef-4c0f0608f176 is not one of the all
 
 AT_BANNER([OVSDB -- atoms with other constraints])
 
-OVSDB_CHECK_POSITIVE([integers >= 5], 
+OVSDB_CHECK_POSITIVE_CPY([integers >= 5], 
   [[parse-atoms '[{"type": "integer", "minInteger": 5}]' \
     '[0]' \
     '[4]' \
@@ -359,7 +360,7 @@ constraint violation: 4 is less than minimum allowed value 5
 6
 12345])
 
-OVSDB_CHECK_POSITIVE([integers <= -1], 
+OVSDB_CHECK_POSITIVE_CPY([integers <= -1], 
   [[parse-atoms '[{"type": "integer", "maxInteger": -1}]' \
     '[0]' \
     '[-1]' \
@@ -370,7 +371,7 @@ OVSDB_CHECK_POSITIVE([integers <= -1],
 -2
 -123])
 
-OVSDB_CHECK_POSITIVE([integers in range -10 to 10], 
+OVSDB_CHECK_POSITIVE_CPY([integers in range -10 to 10], 
   [[parse-atoms '[{"type": "integer", "minInteger": -10, "maxInteger": 10}]' \
     '[-20]' \
     '[-11]' \
@@ -391,7 +392,7 @@ constraint violation: -11 is not in the valid range -10 to 10 (inclusive)
 constraint violation: 11 is not in the valid range -10 to 10 (inclusive)
 constraint violation: 123576 is not in the valid range -10 to 10 (inclusive)])
 
-OVSDB_CHECK_POSITIVE([reals >= 5], 
+OVSDB_CHECK_POSITIVE_CPY([reals >= 5], 
   [[parse-atoms '[{"type": "real", "minReal": 5}]' \
     '[0]' \
     '[4]' \
@@ -404,7 +405,7 @@ constraint violation: 4 is less than minimum allowed value 5
 6
 12345])
 
-OVSDB_CHECK_POSITIVE([reals <= -1], 
+OVSDB_CHECK_POSITIVE_CPY([reals <= -1], 
   [[parse-atoms '[{"type": "real", "maxReal": -1}]' \
     '[0]' \
     '[-1]' \
@@ -415,7 +416,7 @@ OVSDB_CHECK_POSITIVE([reals <= -1],
 -2
 -123])
 
-OVSDB_CHECK_POSITIVE([reals in range -10 to 10], 
+OVSDB_CHECK_POSITIVE_CPY([reals in range -10 to 10], 
   [[parse-atoms '[{"type": "real", "minReal": -10, "maxReal": 10}]' \
     '[-20]' \
     '[-11]' \
@@ -436,7 +437,7 @@ constraint violation: -11 is not in the valid range -10 to 10 (inclusive)
 constraint violation: 11 is not in the valid range -10 to 10 (inclusive)
 constraint violation: 123576 is not in the valid range -10 to 10 (inclusive)])
 
-OVSDB_CHECK_POSITIVE([strings at least 2 characters long],
+OVSDB_CHECK_POSITIVE_CPY([strings at least 2 characters long],
   [[parse-atoms '{"type": "string", "minLength": 2}' \
     '[""]' \
     '["a"]' \
@@ -447,9 +448,10 @@ OVSDB_CHECK_POSITIVE([strings at least 2 characters long],
 constraint violation: "a" length 1 is less than minimum allowed length 2
 "ab"
 "abc"
-constraint violation: "𝄞" length 1 is less than minimum allowed length 2]])
+constraint violation: "𝄞" length 1 is less than minimum allowed length 2]],
+  [], [], [xfail])
 
-OVSDB_CHECK_POSITIVE([strings no more than 2 characters long],
+OVSDB_CHECK_POSITIVE_CPY([strings no more than 2 characters long],
   [[parse-atoms '{"type": "string", "maxLength": 2}' \
     '[""]' \
     '["a"]' \
@@ -464,7 +466,7 @@ constraint violation: "abc" length 3 is greater than maximum allowed length 2
 
 AT_BANNER([OSVDB -- simple data])
 
-OVSDB_CHECK_POSITIVE([integer JSON datum],
+OVSDB_CHECK_POSITIVE_CPY([integer JSON datum],
   [[parse-data '["integer"]' '[0]' '["set",[1]]' '[-1]']],
   [0
 1
@@ -477,7 +479,7 @@ OVSDB_CHECK_POSITIVE([integer string datum],
 -1
 1])
 
-OVSDB_CHECK_POSITIVE([real JSON datum], 
+OVSDB_CHECK_POSITIVE_CPY([real JSON datum], 
   [[parse-data '["real"]' '[0]' '["set",[1.0]]' '[-1.25]']],
   [0
 1
@@ -489,7 +491,7 @@ OVSDB_CHECK_POSITIVE([real string datum],
 1
 -1.25])
 
-OVSDB_CHECK_POSITIVE([boolean JSON datum],
+OVSDB_CHECK_POSITIVE_CPY([boolean JSON datum],
   [[parse-data '["boolean"]' '["set", [true]]' '[false]' ]],
   [true
 false])
@@ -499,7 +501,7 @@ OVSDB_CHECK_POSITIVE([boolean string datum],
   [true
 false])
 
-OVSDB_CHECK_POSITIVE([string JSON datum],
+OVSDB_CHECK_POSITIVE_CPY([string JSON datum],
   [[parse-data '["string"]' '["set",[""]]' '["true"]' '["\"\\\/\b\f\n\r\t"]']],
   [""
 "true"
@@ -514,7 +516,7 @@ OVSDB_CHECK_POSITIVE([string string datum],
 
 AT_BANNER([OVSDB -- set data])
 
-OVSDB_CHECK_POSITIVE([JSON optional boolean],
+OVSDB_CHECK_POSITIVE_CPY([JSON optional boolean],
   [[parse-data '{"key": "boolean", "min": 0}' \
     '[true]' \
     '["set", [false]]' \
@@ -534,7 +536,7 @@ false
 []]],
   [set])
 
-OVSDB_CHECK_POSITIVE([JSON set of 0 or more integers],
+OVSDB_CHECK_POSITIVE_CPY([JSON set of 0 or more integers],
   [[parse-data '{"key": "integer", "min": 0, "max": "unlimited"}' \
     '["set", [0]]' \
     '[1]' \
@@ -566,7 +568,7 @@ OVSDB_CHECK_POSITIVE([string set of 0 or more integers],
 [0, 1, 2, 3, 4, 5, 6, 7, 8]
 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]]])
 
-OVSDB_CHECK_POSITIVE([JSON set of 1 to 3 uuids],
+OVSDB_CHECK_POSITIVE_CPY([JSON set of 1 to 3 uuids],
   [[parse-data '{"key": "uuid", "min": 1, "max": 3}' \
     '["set", [["uuid", "550e8400-e29b-41d4-a716-446655440000"]]]' \
     '["uuid", "b5078be0-7664-4299-b836-8bcc03ef941f"]' \
@@ -586,7 +588,7 @@ OVSDB_CHECK_POSITIVE([string set of 1 to 3 uuids],
   [[[550e8400-e29b-41d4-a716-446655440000]
 [550e8400-e29b-41d4-a716-446655440000, 90558331-09af-4d2f-a572-509cad2e9088, c5051240-30ff-43ed-b4b9-93cf3f050813]]])
 
-OVSDB_CHECK_POSITIVE([JSON set of 0 to 3 strings],
+OVSDB_CHECK_POSITIVE_CPY([JSON set of 0 to 3 strings],
   [[parse-data '{"key": "string", "min": 0, "max": 3}' \
     '["set", []]' \
     '["a longer string"]' \
@@ -610,7 +612,7 @@ OVSDB_CHECK_POSITIVE([string set of 0 to 3 strings],
 ["a relatively long string", "short string"]
 ["a relatively long string", "short string", zzz]]])
 
-OVSDB_CHECK_NEGATIVE([duplicate boolean not allowed in JSON set],
+OVSDB_CHECK_NEGATIVE_CPY([duplicate boolean not allowed in JSON set],
   [[parse-data '{"key": "boolean", "max": 5}' '["set", [true, true]]']],
   [ovsdb error: set contains duplicate])
 
@@ -618,7 +620,7 @@ OVSDB_CHECK_NEGATIVE([duplicate boolean not allowed in string set],
   [[parse-data-strings '{"key": "boolean", "max": 5}' 'true, true']],
   [set contains duplicate value])
 
-OVSDB_CHECK_NEGATIVE([duplicate integer not allowed in JSON set],
+OVSDB_CHECK_NEGATIVE_CPY([duplicate integer not allowed in JSON set],
   [[parse-data '{"key": "integer", "max": 5}' '["set", [1, 2, 3, 1]]']],
   [ovsdb error: set contains duplicate])
 
@@ -626,7 +628,7 @@ OVSDB_CHECK_NEGATIVE([duplicate integer not allowed in string set],
   [[parse-data-strings '{"key": "integer", "max": 5}' '[1, 2, 3, 1]']],
   [set contains duplicate value])
 
-OVSDB_CHECK_NEGATIVE([duplicate real not allowed in JSON set],
+OVSDB_CHECK_NEGATIVE_CPY([duplicate real not allowed in JSON set],
   [[parse-data '{"key": "real", "max": 5}' '["set", [0.0, -0.0]]']],
   [ovsdb error: set contains duplicate])
 
@@ -634,7 +636,7 @@ OVSDB_CHECK_NEGATIVE([duplicate real not allowed in string set],
   [[parse-data-strings '{"key": "real", "max": 5}' '0.0, -0.0']],
   [set contains duplicate value])
 
-OVSDB_CHECK_NEGATIVE([duplicate string not allowed in JSON set],
+OVSDB_CHECK_NEGATIVE_CPY([duplicate string not allowed in JSON set],
   [[parse-data '{"key": "string", "max": 5}' '["set", ["asdf", "ASDF", "asdf"]]']],
   [ovsdb error: set contains duplicate])
 
@@ -642,7 +644,7 @@ OVSDB_CHECK_NEGATIVE([duplicate string not allowed in string set],
   [[parse-data-strings '{"key": "string", "max": 5}' 'asdf, ASDF, "asdf"']],
   [set contains duplicate value])
 
-OVSDB_CHECK_NEGATIVE([duplicate uuid not allowed in JSON set],
+OVSDB_CHECK_NEGATIVE_CPY([duplicate uuid not allowed in JSON set],
   [[parse-data '{"key": "uuid", "max": 5}' \
     '["set", [["uuid", "7ef21525-0088-4a28-a418-5518413e43ea"],
               ["uuid", "355ad037-f1da-40aa-b47c-ff9c7e8c6a38"],
@@ -658,7 +660,7 @@ OVSDB_CHECK_NEGATIVE([duplicate uuid not allowed in string set],
 
 AT_BANNER([OVSDB -- map data])
 
-OVSDB_CHECK_POSITIVE([JSON map of 1 integer to boolean],
+OVSDB_CHECK_POSITIVE_CPY([JSON map of 1 integer to boolean],
   [[parse-data '{"key": "integer", "value": "boolean"}' \
     '["map", [[1, true]]]']],
   [[["map",[[1,true]]]]])
@@ -668,7 +670,7 @@ OVSDB_CHECK_POSITIVE([string map of 1 integer to boolean],
     '1=true']],
   [[1=true]])
 
-OVSDB_CHECK_POSITIVE([JSON map of at least 1 integer to boolean],
+OVSDB_CHECK_POSITIVE_CPY([JSON map of at least 1 integer to boolean],
   [[parse-data '{"key": "integer", "value": "boolean", "max": "unlimited"}' \
     '["map", [[1, true]]]' \
     '["map", [[0, true], [1, false], [2, true], [3, true], [4, true]]]' \
@@ -686,7 +688,7 @@ OVSDB_CHECK_POSITIVE([string map of at least 1 integer to boolean],
 {0=true, 1=false, 2=true, 3=true, 4=true}
 {0=true, 3=false, 4=false}]])
 
-OVSDB_CHECK_POSITIVE([JSON map of 1 boolean to integer],
+OVSDB_CHECK_POSITIVE_CPY([JSON map of 1 boolean to integer],
  [[parse-data '{"key": "boolean", "value": "integer"}' \
    '["map", [[true, 1]]]']],
  [[["map",[[true,1]]]]])
@@ -696,7 +698,7 @@ OVSDB_CHECK_POSITIVE([string map of 1 boolean to integer],
    'true=1']],
  [[true=1]])
 
-OVSDB_CHECK_POSITIVE([JSON map of 1 uuid to real],
+OVSDB_CHECK_POSITIVE_CPY([JSON map of 1 uuid to real],
   [[parse-data '{"key": "uuid", "value": "real", "min": 1, "max": 5}' \
     '["map", [[["uuid", "cad8542b-6ee1-486b-971b-7dcbf6e14979"], 1.0],
 	      [["uuid", "6b94b968-2702-4f64-9457-314a34d69b8c"], 2.0],
@@ -714,7 +716,7 @@ OVSDB_CHECK_POSITIVE([string map of 1 uuid to real],
      1c92b8ca-d5e4-4628-a85d-1dc2d099a99a=5.0']],
   [[{1c92b8ca-d5e4-4628-a85d-1dc2d099a99a=5, 25bfa475-d072-4f60-8be1-00f48643e9cb=4, 6b94b968-2702-4f64-9457-314a34d69b8c=2, cad8542b-6ee1-486b-971b-7dcbf6e14979=1, d2c4a168-24de-47eb-a8a3-c1abfc814979=3}]])
 
-OVSDB_CHECK_POSITIVE([JSON map of 10 string to string],
+OVSDB_CHECK_POSITIVE_CPY([JSON map of 10 string to string],
   [[parse-data '{"key": "string", "value": "string", "min": 1, "max": 10}' \
     '["map", [["2 gills", "1 chopin"],
 	      ["2 chopins", "1 pint"],
@@ -742,7 +744,7 @@ OVSDB_CHECK_POSITIVE([string map of 10 string to string],
       "2 kilderkins"= "1 barrel"}']],
    [[{"2 chopins"="1 pint", "2 demibushel"="1 firkin", "2 firkins"="1 kilderkin", "2 gallons"="1 peck", "2 gills"="1 chopin", "2 kilderkins"="1 barrel", "2 pecks"="1 demibushel", "2 pints"="1 quart", "2 pottles"="1 gallon", "2 quarts"="1 pottle"}]])
 
-OVSDB_CHECK_NEGATIVE([duplicate integer key not allowed in JSON map],
+OVSDB_CHECK_NEGATIVE_CPY([duplicate integer key not allowed in JSON map],
   [[parse-data '{"key": "integer", "value": "boolean", "max": 5}' \
     '["map", [[1, true], [2, false], [1, false]]]']],
   [ovsdb error: map contains duplicate key])
diff --git a/tests/ovsdb-idl-py.at b/tests/ovsdb-idl-py.at
new file mode 100644
index 000000000..5f7661bf2
--- /dev/null
+++ b/tests/ovsdb-idl-py.at
@@ -0,0 +1,149 @@
+AT_BANNER([OVSDB -- interface description language (IDL) - Python])
+
+# OVSDB_CHECK_IDL(TITLE, [PRE-IDL-TXN], TRANSACTIONS, OUTPUT, [KEYWORDS],
+#                 [FILTER])
+#
+# Creates a database with a schema derived from idltest.ovsidl, runs
+# each PRE-IDL-TXN (if any), starts an ovsdb-server on that database,
+# and runs "test-ovsdb idl" passing each of the TRANSACTIONS along.
+#
+# Checks that the overall output is OUTPUT.  Before comparison, the
+# output is sorted (using "sort") and UUIDs in the output are replaced
+# by markers of the form <N> where N is a number.  The first unique
+# UUID is replaced by <0>, the next by <1>, and so on.  If a given
+# UUID appears more than once it is always replaced by the same
+# marker.  If FILTER is supplied then the output is also filtered
+# through the specified program.
+#
+# TITLE is provided to AT_SETUP and KEYWORDS to AT_KEYWORDS.
+m4_define([OVSDB_CHECK_IDL_PY], 
+  [AT_SETUP([$1])
+   AT_SKIP_IF([test $HAVE_PYTHON = no])
+   AT_KEYWORDS([ovsdb server idl positive Python $5])
+   AT_CHECK([ovsdb-tool create db $abs_srcdir/idltest.ovsschema],
+                  [0], [stdout], [ignore])
+   AT_CHECK([ovsdb-server '-vPATTERN:console:ovsdb-server|%c|%m' --detach --pidfile=$PWD/pid --remote=punix:socket --unixctl=$PWD/unixctl db], [0], [ignore], [ignore])
+   m4_if([$2], [], [],
+     [AT_CHECK([ovsdb-client transact unix:socket $2], [0], [ignore], [ignore], [kill `cat pid`])])
+   AT_CHECK([$PYTHON $srcdir/test-ovsdb.py  -t10 idl unix:socket $3], 
+            [0], [stdout], [ignore], [kill `cat pid`])
+   AT_CHECK([sort stdout | perl $srcdir/uuidfilt.pl]m4_if([$6],,, [[| $6]]),
+            [0], [$4], [], [kill `cat pid`])
+   OVSDB_SERVER_SHUTDOWN
+   AT_CLEANUP])
+
+OVSDB_CHECK_IDL_PY([simple idl, initially empty, no ops - Python],
+  [],
+  [],
+  [000: empty
+001: done
+])
+
+OVSDB_CHECK_IDL([simple idl, initially empty, various ops - Python],
+  [],
+  [['["idltest",
+      {"op": "insert",
+       "table": "simple",
+       "row": {"i": 1,
+               "r": 2.0,
+               "b": true,
+               "s": "mystring",
+               "u": ["uuid", "84f5c8f5-ac76-4dbc-a24f-8860eb407fc1"],
+               "ia": ["set", [1, 2, 3]],
+               "ra": ["set", [-0.5]],
+               "ba": ["set", [true, false]],
+               "sa": ["set", ["abc", "def"]], 
+               "ua": ["set", [["uuid", "69443985-7806-45e2-b35f-574a04e720f9"],
+                              ["uuid", "aad11ef0-816a-4b01-93e6-03b8b4256b98"]]]}},
+      {"op": "insert",
+       "table": "simple",
+       "row": {}}]' \
+    '["idltest",
+      {"op": "update",
+       "table": "simple",
+       "where": [],
+       "row": {"b": true}}]' \
+    '["idltest",
+      {"op": "update",
+       "table": "simple",
+       "where": [],
+       "row": {"r": 123.5}}]' \
+    '["idltest",
+      {"op": "insert",
+       "table": "simple",
+       "row": {"i": -1,
+               "r": 125,
+               "b": false,
+               "s": "",
+               "ia": ["set", [1]],
+               "ra": ["set", [1.5]],
+               "ba": ["set", [false]],
+               "sa": ["set", []], 
+               "ua": ["set", []]}}]' \
+    '["idltest",
+      {"op": "update",
+       "table": "simple",
+       "where": [["i", "<", 1]],
+       "row": {"s": "newstring"}}]' \
+    '["idltest",
+      {"op": "delete",
+       "table": "simple",
+       "where": [["i", "==", 0]]}]' \
+    'reconnect']],
+  [[000: empty
+001: {"error":null,"result":[{"uuid":["uuid","<0>"]},{"uuid":["uuid","<1>"]}]}
+002: i=0 r=0 b=false s= u=<2> ia=[] ra=[] ba=[] sa=[] ua=[] uuid=<1>
+002: i=1 r=2 b=true s=mystring u=<3> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<4> <5>] uuid=<0>
+003: {"error":null,"result":[{"count":2}]}
+004: i=0 r=0 b=true s= u=<2> ia=[] ra=[] ba=[] sa=[] ua=[] uuid=<1>
+004: i=1 r=2 b=true s=mystring u=<3> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<4> <5>] uuid=<0>
+005: {"error":null,"result":[{"count":2}]}
+006: i=0 r=123.5 b=true s= u=<2> ia=[] ra=[] ba=[] sa=[] ua=[] uuid=<1>
+006: i=1 r=123.5 b=true s=mystring u=<3> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<4> <5>] uuid=<0>
+007: {"error":null,"result":[{"uuid":["uuid","<6>"]}]}
+008: i=-1 r=125 b=false s= u=<2> ia=[1] ra=[1.5] ba=[false] sa=[] ua=[] uuid=<6>
+008: i=0 r=123.5 b=true s= u=<2> ia=[] ra=[] ba=[] sa=[] ua=[] uuid=<1>
+008: i=1 r=123.5 b=true s=mystring u=<3> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<4> <5>] uuid=<0>
+009: {"error":null,"result":[{"count":2}]}
+010: i=-1 r=125 b=false s=newstring u=<2> ia=[1] ra=[1.5] ba=[false] sa=[] ua=[] uuid=<6>
+010: i=0 r=123.5 b=true s=newstring u=<2> ia=[] ra=[] ba=[] sa=[] ua=[] uuid=<1>
+010: i=1 r=123.5 b=true s=mystring u=<3> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<4> <5>] uuid=<0>
+011: {"error":null,"result":[{"count":1}]}
+012: i=-1 r=125 b=false s=newstring u=<2> ia=[1] ra=[1.5] ba=[false] sa=[] ua=[] uuid=<6>
+012: i=1 r=123.5 b=true s=mystring u=<3> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<4> <5>] uuid=<0>
+013: reconnect
+014: i=-1 r=125 b=false s=newstring u=<2> ia=[1] ra=[1.5] ba=[false] sa=[] ua=[] uuid=<6>
+014: i=1 r=123.5 b=true s=mystring u=<3> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<4> <5>] uuid=<0>
+015: done
+]])
+
+OVSDB_CHECK_IDL([simple idl, initially populated - Python],
+  [['["idltest",
+      {"op": "insert",
+       "table": "simple",
+       "row": {"i": 1,
+               "r": 2.0,
+               "b": true,
+               "s": "mystring",
+               "u": ["uuid", "84f5c8f5-ac76-4dbc-a24f-8860eb407fc1"],
+               "ia": ["set", [1, 2, 3]],
+               "ra": ["set", [-0.5]],
+               "ba": ["set", [true, false]],
+               "sa": ["set", ["abc", "def"]], 
+               "ua": ["set", [["uuid", "69443985-7806-45e2-b35f-574a04e720f9"],
+                              ["uuid", "aad11ef0-816a-4b01-93e6-03b8b4256b98"]]]}},
+      {"op": "insert",
+       "table": "simple",
+       "row": {}}]']],
+  [['["idltest",
+      {"op": "update",
+       "table": "simple",
+       "where": [],
+       "row": {"b": true}}]']],
+  [[000: i=0 r=0 b=false s= u=<0> ia=[] ra=[] ba=[] sa=[] ua=[] uuid=<1>
+000: i=1 r=2 b=true s=mystring u=<2> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<3> <4>] uuid=<5>
+001: {"error":null,"result":[{"count":2}]}
+002: i=0 r=0 b=true s= u=<0> ia=[] ra=[] ba=[] sa=[] ua=[] uuid=<1>
+002: i=1 r=2 b=true s=mystring u=<2> ia=[1 2 3] ra=[-0.5] ba=[false true] sa=[abc def] ua=[<3> <4>] uuid=<5>
+003: done
+]])
diff --git a/tests/ovsdb-schema.at b/tests/ovsdb-schema.at
index 6cd2fa20f..008cc4316 100644
--- a/tests/ovsdb-schema.at
+++ b/tests/ovsdb-schema.at
@@ -1,6 +1,6 @@
 AT_BANNER([OVSDB -- schemas])
 
-OVSDB_CHECK_POSITIVE([schema with valid refTables],
+OVSDB_CHECK_POSITIVE_CPY([schema with valid refTables],
   [[parse-schema \
       '{"name": "mydb",
         "tables": {
@@ -23,7 +23,7 @@ OVSDB_CHECK_POSITIVE([schema with valid refTables],
                     "refTable": "a"}}}}}}}']],
   [[{"name":"mydb","tables":{"a":{"columns":{"map":{"type":{"key":{"refTable":"b","type":"uuid"},"value":{"refTable":"a","type":"uuid"}}}}},"b":{"columns":{"aRef":{"type":{"key":{"refTable":"a","type":"uuid"}}}}}}}]])
      
-OVSDB_CHECK_NEGATIVE([schema with invalid refTables],
+OVSDB_CHECK_NEGATIVE_CPY([schema with invalid refTables],
   [[parse-schema \
       '{"name": "mydb",
         "tables": {
@@ -44,4 +44,4 @@ OVSDB_CHECK_NEGATIVE([schema with invalid refTables],
                   "key": {
                     "type": "uuid",
                     "refTable": "a"}}}}}}}']],
-  [[test-ovsdb: syntax error: column map key refers to undefined table c]])
+  [[syntax error: column map key refers to undefined table c]])
diff --git a/tests/ovsdb-table.at b/tests/ovsdb-table.at
index 623dd6dd0..70f8ac252 100644
--- a/tests/ovsdb-table.at
+++ b/tests/ovsdb-table.at
@@ -1,35 +1,35 @@
 AT_BANNER([OVSDB -- tables])
 
-OVSDB_CHECK_POSITIVE([table with one column],
+OVSDB_CHECK_POSITIVE_CPY([table with one column],
   [[parse-table mytable '{"columns": {"name": {"type": "string"}}}']],
   [[{"columns":{"name":{"type":"string"}}}]])
 
-OVSDB_CHECK_POSITIVE([immutable table with one column],
+OVSDB_CHECK_POSITIVE_CPY([immutable table with one column],
   [[parse-table mytable \
     '{"columns": {"name": {"type": "string"}},
       "mutable": false}']],
   [[{"columns":{"name":{"type":"string"}},"mutable":false}]])
 
-OVSDB_CHECK_POSITIVE([table with maxRows of 2],
+OVSDB_CHECK_POSITIVE_CPY([table with maxRows of 2],
   [[parse-table mytable '{"columns": {"name": {"type": "string"}}, 
                           "maxRows": 2}']],
   [[{"columns":{"name":{"type":"string"}},"maxRows":2}]])
 
-OVSDB_CHECK_NEGATIVE([column names may not begin with _],
+OVSDB_CHECK_NEGATIVE_CPY([column names may not begin with _],
   [[parse-table mytable \
     '{"columns": {"_column": {"type": "integer"}}}']],
   [[names beginning with "_" are reserved]],
   [table])
 
-OVSDB_CHECK_NEGATIVE([table must have at least one column (1)],
+OVSDB_CHECK_NEGATIVE_CPY([table must have at least one column (1)],
   [[parse-table mytable '{}']],
   [[Parsing table schema for table mytable failed: Required 'columns' member is missing.]])
 
-OVSDB_CHECK_NEGATIVE([table must have at least one column (2)],
+OVSDB_CHECK_NEGATIVE_CPY([table must have at least one column (2)],
   [[parse-table mytable '{"columns": {}}']],
   [[table must have at least one column]])
 
-OVSDB_CHECK_NEGATIVE([table maxRows must be positive],
+OVSDB_CHECK_NEGATIVE_CPY([table maxRows must be positive],
   [[parse-table mytable '{"columns": {"name": {"type": "string"}}, 
                           "maxRows": 0}']],
   [[syntax "{"columns":{"name":{"type":"string"}},"maxRows":0}": syntax error: maxRows must be at least 1]])
diff --git a/tests/ovsdb-types.at b/tests/ovsdb-types.at
index 7122e9d2d..7bba84601 100644
--- a/tests/ovsdb-types.at
+++ b/tests/ovsdb-types.at
@@ -1,167 +1,167 @@
 AT_BANNER([OVSDB -- atomic types])
 
-OVSDB_CHECK_POSITIVE([integer], 
+OVSDB_CHECK_POSITIVE_CPY([integer], 
   [[parse-atomic-type '["integer"]' ]], ["integer"])
-OVSDB_CHECK_POSITIVE([real], 
+OVSDB_CHECK_POSITIVE_CPY([real], 
   [[parse-atomic-type '["real"]' ]], ["real"])
-OVSDB_CHECK_POSITIVE([boolean], 
+OVSDB_CHECK_POSITIVE_CPY([boolean], 
   [[parse-atomic-type '["boolean"]' ]], ["boolean"])
-OVSDB_CHECK_POSITIVE([string], 
+OVSDB_CHECK_POSITIVE_CPY([string], 
   [[parse-atomic-type '["string"]' ]], ["string"])
-OVSDB_CHECK_POSITIVE([uuid], 
+OVSDB_CHECK_POSITIVE_CPY([uuid], 
   [[parse-atomic-type '["uuid"]' ]], ["uuid"])
-OVSDB_CHECK_NEGATIVE([void is not a valid atomic-type],
+OVSDB_CHECK_NEGATIVE_CPY([void is not a valid atomic-type],
   [[parse-atomic-type '["void"]' ]], ["void" is not an atomic-type])
 
 AT_BANNER([OVSDB -- base types])
 
-OVSDB_CHECK_POSITIVE([integer enum],
+OVSDB_CHECK_POSITIVE_CPY([integer enum],
   [[parse-base-type '{"type": "integer", "enum": ["set", [-1, 4, 5]]}' ]],
   [[{"enum":["set",[-1,4,5]],"type":"integer"}]])
-OVSDB_CHECK_POSITIVE([integer >= 5], 
+OVSDB_CHECK_POSITIVE_CPY([integer >= 5], 
   [[parse-base-type '{"type": "integer", "minInteger": 5}' ]],
   [{"minInteger":5,"type":"integer"}])
-OVSDB_CHECK_POSITIVE([integer <= 7], 
+OVSDB_CHECK_POSITIVE_CPY([integer <= 7], 
   [[parse-base-type '{"type": "integer", "maxInteger": 7}' ]],
   [{"maxInteger":7,"type":"integer"}])
-OVSDB_CHECK_POSITIVE([integer between -5 and 10], 
+OVSDB_CHECK_POSITIVE_CPY([integer between -5 and 10], 
   [[parse-base-type '{"type": "integer", "minInteger": -5, "maxInteger": 10}']],
   [{"maxInteger":10,"minInteger":-5,"type":"integer"}])
-OVSDB_CHECK_NEGATIVE([integer max may not be less than min],
+OVSDB_CHECK_NEGATIVE_CPY([integer max may not be less than min],
   [[parse-base-type '{"type": "integer", "minInteger": 5, "maxInteger": 3}']],
   [minInteger exceeds maxInteger])
 
-OVSDB_CHECK_POSITIVE([real enum],
+OVSDB_CHECK_POSITIVE_CPY([real enum],
   [[parse-base-type '{"type": "real", "enum": ["set", [1.5, 0, 2.75]]}' ]],
   [[{"enum":["set",[0,1.5,2.75]],"type":"real"}]])
-OVSDB_CHECK_POSITIVE([real >= -1.5], 
+OVSDB_CHECK_POSITIVE_CPY([real >= -1.5], 
   [[parse-base-type '{"type": "real", "minReal": -1.5}']],
   [{"minReal":-1.5,"type":"real"}])
-OVSDB_CHECK_POSITIVE([real <= 1e5], 
+OVSDB_CHECK_POSITIVE_CPY([real <= 1e5], 
   [[parse-base-type '{"type": "real", "maxReal": 1e5}']],
   [{"maxReal":100000,"type":"real"}])
-OVSDB_CHECK_POSITIVE([real between -2.5 and 3.75], 
+OVSDB_CHECK_POSITIVE_CPY([real between -2.5 and 3.75], 
   [[parse-base-type '{"type": "real", "minReal": -2.5, "maxReal": 3.75}']],
   [{"maxReal":3.75,"minReal":-2.5,"type":"real"}])
-OVSDB_CHECK_NEGATIVE([real max may not be less than min], 
+OVSDB_CHECK_NEGATIVE_CPY([real max may not be less than min], 
   [[parse-base-type '{"type": "real", "minReal": 555, "maxReal": 444}']],
   [minReal exceeds maxReal])
 
-OVSDB_CHECK_POSITIVE([boolean], 
+OVSDB_CHECK_POSITIVE_CPY([boolean], 
   [[parse-base-type '[{"type": "boolean"}]' ]], ["boolean"])
-OVSDB_CHECK_POSITIVE([boolean enum],
+OVSDB_CHECK_POSITIVE_CPY([boolean enum],
   [[parse-base-type '{"type": "boolean", "enum": true}' ]],
   [[{"enum":true,"type":"boolean"}]])
 
-OVSDB_CHECK_POSITIVE([string enum], 
+OVSDB_CHECK_POSITIVE_CPY([string enum], 
   [[parse-base-type '{"type": "string", "enum": ["set", ["def", "abc"]]}']],
   [[{"enum":["set",["abc","def"]],"type":"string"}]])
-OVSDB_CHECK_POSITIVE([string minLength], 
+OVSDB_CHECK_POSITIVE_CPY([string minLength], 
   [[parse-base-type '{"type": "string", "minLength": 1}']],
   [{"minLength":1,"type":"string"}])
-OVSDB_CHECK_POSITIVE([string maxLength], 
+OVSDB_CHECK_POSITIVE_CPY([string maxLength], 
   [[parse-base-type '{"type": "string", "maxLength": 5}']],
   [{"maxLength":5,"type":"string"}])
-OVSDB_CHECK_POSITIVE([string minLength and maxLength], 
+OVSDB_CHECK_POSITIVE_CPY([string minLength and maxLength], 
   [[parse-base-type '{"type": "string", "minLength": 1, "maxLength": 5}']],
   [{"maxLength":5,"minLength":1,"type":"string"}])
-OVSDB_CHECK_NEGATIVE([maxLength must not be less than minLength], 
+OVSDB_CHECK_NEGATIVE_CPY([maxLength must not be less than minLength], 
   [[parse-base-type '{"type": "string", "minLength": 5, "maxLength": 3}']],
   [minLength exceeds maxLength])
-OVSDB_CHECK_NEGATIVE([maxLength must not be negative], 
+OVSDB_CHECK_NEGATIVE_CPY([maxLength must not be negative], 
   [[parse-base-type '{"type": "string", "maxLength": -1}']],
   [maxLength out of valid range 0 to 4294967295])
 
-OVSDB_CHECK_POSITIVE([uuid enum], 
+OVSDB_CHECK_POSITIVE_CPY([uuid enum], 
   [[parse-base-type '{"type": "uuid", "enum": ["uuid", "36bf19c0-ad9d-4232-bb85-b3d73dfe2123"]}' ]],
   [[{"enum":["uuid","36bf19c0-ad9d-4232-bb85-b3d73dfe2123"],"type":"uuid"}]])
-OVSDB_CHECK_POSITIVE([uuid refTable], 
+OVSDB_CHECK_POSITIVE_CPY([uuid refTable], 
   [[parse-base-type '{"type": "uuid", "refTable": "myTable"}' ]],
   [{"refTable":"myTable","type":"uuid"}])
-OVSDB_CHECK_NEGATIVE([uuid refTable must be valid id], 
+OVSDB_CHECK_NEGATIVE_CPY([uuid refTable must be valid id], 
   [[parse-base-type '{"type": "uuid", "refTable": "a-b-c"}' ]],
   [Type mismatch for member 'refTable'])
 
-OVSDB_CHECK_NEGATIVE([void is not a valid base-type],
+OVSDB_CHECK_NEGATIVE_CPY([void is not a valid base-type],
   [[parse-base-type '["void"]' ]], ["void" is not an atomic-type])
-OVSDB_CHECK_NEGATIVE(["type" member must be present],
+OVSDB_CHECK_NEGATIVE_CPY(["type" member must be present],
   [[parse-base-type '{}']], [Parsing ovsdb type failed: Required 'type' member is missing.])
 
 AT_BANNER([OVSDB -- simple types])
 
-OVSDB_CHECK_POSITIVE([simple integer], 
+OVSDB_CHECK_POSITIVE_CPY([simple integer], 
   [[parse-type '["integer"]' ]], ["integer"])
-OVSDB_CHECK_POSITIVE([simple real], 
+OVSDB_CHECK_POSITIVE_CPY([simple real], 
   [[parse-type '["real"]' ]], ["real"])
-OVSDB_CHECK_POSITIVE([simple boolean], 
+OVSDB_CHECK_POSITIVE_CPY([simple boolean], 
   [[parse-type '["boolean"]' ]], ["boolean"])
-OVSDB_CHECK_POSITIVE([simple string], 
+OVSDB_CHECK_POSITIVE_CPY([simple string], 
   [[parse-type '["string"]' ]], ["string"])
-OVSDB_CHECK_POSITIVE([simple uuid], 
+OVSDB_CHECK_POSITIVE_CPY([simple uuid], 
   [[parse-type '["uuid"]' ]], ["uuid"])
-OVSDB_CHECK_POSITIVE([integer in object],
+OVSDB_CHECK_POSITIVE_CPY([integer in object],
   [[parse-type '{"key": "integer"}' ]], ["integer"])
-OVSDB_CHECK_POSITIVE([real in object with explicit min and max],
+OVSDB_CHECK_POSITIVE_CPY([real in object with explicit min and max],
   [[parse-type '{"key": "real", "min": 1, "max": 1}' ]], ["real"])
 
-OVSDB_CHECK_NEGATIVE([key type is required],
+OVSDB_CHECK_NEGATIVE_CPY([key type is required],
   [[parse-type '{}' ]], [Required 'key' member is missing.])
-OVSDB_CHECK_NEGATIVE([void is not a valid type],
+OVSDB_CHECK_NEGATIVE_CPY([void is not a valid type],
   [[parse-type '["void"]' ]], ["void" is not an atomic-type])
 
 AT_BANNER([OVSDB -- set types])
 
-OVSDB_CHECK_POSITIVE([optional boolean],
+OVSDB_CHECK_POSITIVE_CPY([optional boolean],
   [[parse-type '{"key": "boolean", "min": 0}' ]], 
   [[{"key":"boolean","min":0}]],
   [set])
-OVSDB_CHECK_POSITIVE([set of 1 to 3 uuids],
+OVSDB_CHECK_POSITIVE_CPY([set of 1 to 3 uuids],
   [[parse-type '{"key": "uuid", "min": 1, "max": 3}' ]], 
   [[{"key":"uuid","max":3}]])
-OVSDB_CHECK_POSITIVE([set of 0 to 3 strings],
+OVSDB_CHECK_POSITIVE_CPY([set of 0 to 3 strings],
   [[parse-type '{"key": "string", "min": 0, "max": 3}' ]], 
   [[{"key":"string","max":3,"min":0}]])
-OVSDB_CHECK_POSITIVE([set of 0 or more integers],
+OVSDB_CHECK_POSITIVE_CPY([set of 0 or more integers],
   [[parse-type '{"key": "integer", "min": 0, "max": "unlimited"}']],
   [[{"key":"integer","max":"unlimited","min":0}]])
-OVSDB_CHECK_POSITIVE([set of 1 or more reals],
+OVSDB_CHECK_POSITIVE_CPY([set of 1 or more reals],
   [[parse-type '{"key": "real", "min": 1, "max": "unlimited"}']],
   [[{"key":"real","max":"unlimited"}]])
 
-OVSDB_CHECK_NEGATIVE([set max cannot be less than min],
+OVSDB_CHECK_NEGATIVE_CPY([set max cannot be less than min],
   [[parse-type '{"key": "real", "min": 5, "max": 3}' ]],
   [ovsdb type fails constraint checks])
-OVSDB_CHECK_NEGATIVE([set max cannot be negative],
+OVSDB_CHECK_NEGATIVE_CPY([set max cannot be negative],
   [[parse-type '{"key": "real", "max": -1}' ]],
   [bad min or max value])
-OVSDB_CHECK_NEGATIVE([set min cannot be negative],
+OVSDB_CHECK_NEGATIVE_CPY([set min cannot be negative],
   [[parse-type '{"key": "real", "min": -1}' ]],
   [bad min or max value])
-OVSDB_CHECK_NEGATIVE([set min cannot be greater than one],
+OVSDB_CHECK_NEGATIVE_CPY([set min cannot be greater than one],
   [[parse-type '{"key": "real", "min": 10, "max": "unlimited"}']],
   [ovsdb type fails constraint checks])
 
 AT_BANNER([OVSDB -- map types])
 
-OVSDB_CHECK_POSITIVE([map of 1 integer to boolean],
+OVSDB_CHECK_POSITIVE_CPY([map of 1 integer to boolean],
  [[parse-type '{"key": "integer", "value": "boolean"}' ]],
  [[{"key":"integer","value":"boolean"}]])
-OVSDB_CHECK_POSITIVE([map of 1 boolean to integer, explicit min and max],
+OVSDB_CHECK_POSITIVE_CPY([map of 1 boolean to integer, explicit min and max],
  [[parse-type '{"key": "boolean", "value": "integer", "min": 1, "max": 1}' ]],
  [[{"key":"boolean","value":"integer"}]])
-OVSDB_CHECK_POSITIVE([map of 1 to 5 uuid to real],
+OVSDB_CHECK_POSITIVE_CPY([map of 1 to 5 uuid to real],
  [[parse-type '{"key": "uuid", "value": "real", "min": 1, "max": 5}' ]],
  [[{"key":"uuid","max":5,"value":"real"}]])
-OVSDB_CHECK_POSITIVE([map of 0 to 10 string to uuid],
+OVSDB_CHECK_POSITIVE_CPY([map of 0 to 10 string to uuid],
  [[parse-type '{"key": "string", "value": "uuid", "min": 0, "max": 10}' ]],
  [[{"key":"string","max":10,"min":0,"value":"uuid"}]])
-OVSDB_CHECK_POSITIVE([map of 1 to 20 real to string],
+OVSDB_CHECK_POSITIVE_CPY([map of 1 to 20 real to string],
  [[parse-type '{"key": "real", "value": "string", "min": 1, "max": 20}' ]],
  [[{"key":"real","max":20,"value":"string"}]])
-OVSDB_CHECK_POSITIVE([map of 0 or more string to real],
+OVSDB_CHECK_POSITIVE_CPY([map of 0 or more string to real],
  [[parse-type '{"key": "string", "value": "real", "min": 0, "max": "unlimited"}' ]],
  [[{"key":"string","max":"unlimited","min":0,"value":"real"}]])
 
-OVSDB_CHECK_NEGATIVE([map key type is required],
+OVSDB_CHECK_NEGATIVE_CPY([map key type is required],
  [[parse-type '{"value": "integer"}' ]],
  [Required 'key' member is missing.])
diff --git a/tests/ovsdb.at b/tests/ovsdb.at
index 1ee9c0378..d64d75e54 100644
--- a/tests/ovsdb.at
+++ b/tests/ovsdb.at
@@ -11,6 +11,33 @@ m4_define([OVSDB_CHECK_POSITIVE],
 ], [])
    AT_CLEANUP])
 
+# OVSDB_CHECK_POSITIVE_PY(TITLE, TEST-OVSDB-ARGS, OUTPUT, [KEYWORDS], [PREREQ],
+#                         [XFAIL])
+#
+# Runs "test-ovsdb.py TEST-OVSDB-ARGS" and checks that it exits with
+# status 0 and prints OUTPUT on stdout.
+#
+# If XFAIL is nonempty then the test is expected to fail (presumably because
+# this test works in the C implementation but does not work in Python yet)
+#
+# TITLE is provided to AT_SETUP and KEYWORDS to AT_KEYWORDS.
+m4_define([OVSDB_CHECK_POSITIVE_PY], 
+  [AT_SETUP([$1])
+   AT_SKIP_IF([test $HAVE_PYTHON = no])
+   m4_if([$6], [], [], [AT_XFAIL_IF([:])])
+   AT_KEYWORDS([ovsdb positive Python $4])
+   AT_CHECK([$PYTHON $srcdir/test-ovsdb.py $2], [0], [$3
+], [])
+   AT_CLEANUP])
+
+# OVSDB_CHECK_POSITIVE_CPY(TITLE, TEST-OVSDB-ARGS, OUTPUT, [KEYWORDS],
+#                          [PREREQ], [PY-XFAIL])
+#
+# Runs identical C and Python tests, as specified.
+m4_define([OVSDB_CHECK_POSITIVE_CPY],
+  [OVSDB_CHECK_POSITIVE([$1 - C], [$2], [$3], [$4], [$5])
+   OVSDB_CHECK_POSITIVE_PY([$1 - Python], [$2], [$3], [$4], [$5], [$6])])
+
 # OVSDB_CHECK_NEGATIVE(TITLE, TEST-OVSDB-ARGS, OUTPUT, [KEYWORDS], [PREREQ])
 #
 # Runs "test-ovsdb TEST-OVSDB-ARGS" and checks that it exits with
@@ -31,6 +58,35 @@ m4_define([OVSDB_CHECK_NEGATIVE],
             [0], [ignore], [ignore])
    AT_CLEANUP])
 
+# OVSDB_CHECK_NEGATIVE_PY(TITLE, TEST-OVSDB-ARGS, OUTPUT, [KEYWORDS], [PREREQ])
+#
+# Runs "test-ovsdb TEST-OVSDB-ARGS" and checks that it exits with
+# status 1 and that its output on stdout contains substring OUTPUT.
+# TITLE is provided to AT_SETUP and KEYWORDS to AT_KEYWORDS.  
+m4_define([OVSDB_CHECK_NEGATIVE_PY], 
+  [AT_SETUP([$1])
+   AT_SKIP_IF([test $HAVE_PYTHON = no])
+   AT_KEYWORDS([ovsdb negative $4])
+   AT_CHECK([$PYTHON $srcdir/test-ovsdb.py $2], [1], [], [stderr])
+   m4_assert(m4_len([$3]))
+   AT_CHECK(
+     [if grep -F -e "AS_ESCAPE([$3])" stderr
+      then
+        :
+      else
+        exit 99
+      fi], 
+            [0], [ignore], [ignore])
+   AT_CLEANUP])
+
+# OVSDB_CHECK_NEGATIVE_CPY(TITLE, TEST-OVSDB-ARGS, OUTPUT, [KEYWORDS],
+#                          [PREREQ])
+#
+# Runs identical C and Python tests, as specified.
+m4_define([OVSDB_CHECK_NEGATIVE_CPY],
+  [OVSDB_CHECK_NEGATIVE([$1 - C], [$2], [$3], [$4], [$5])
+   OVSDB_CHECK_NEGATIVE_PY([$1 - Python], [$2], [$3], [$4], [$5])])
+
 m4_include([tests/ovsdb-log.at])
 m4_include([tests/ovsdb-types.at])
 m4_include([tests/ovsdb-data.at])
@@ -48,3 +104,4 @@ m4_include([tests/ovsdb-tool.at])
 m4_include([tests/ovsdb-server.at])
 m4_include([tests/ovsdb-monitor.at])
 m4_include([tests/ovsdb-idl.at])
+m4_include([tests/ovsdb-idl-py.at])
diff --git a/tests/reconnect.at b/tests/reconnect.at
index d35e7bff1..559836420 100644
--- a/tests/reconnect.at
+++ b/tests/reconnect.at
@@ -2,13 +2,25 @@ AT_BANNER([reconnect library])
 
 m4_define([__RECONNECT_CHECK],
   [AT_SETUP([$1])
+   $2
    AT_KEYWORDS([reconnect])
-   AT_DATA([input], [$2])
-   AT_CHECK([$3], [0], [$4])
+   AT_DATA([input], [$3])
+   AT_CHECK([$4], [0], [$5])
    AT_CLEANUP])
 
 m4_define([RECONNECT_CHECK],
-  [__RECONNECT_CHECK([$1], [$2], [test-reconnect < input], [$3])])
+  [__RECONNECT_CHECK(
+     [$1 - C],
+     [],
+     [$2],
+     [test-reconnect < input],
+     [$3])
+   __RECONNECT_CHECK(
+     [$1 - Python],
+     [AT_SKIP_IF([test $HAVE_PYTHON = no])],
+     [$2],
+     [$PYTHON $srcdir/test-reconnect.py < input],
+     [$3])])
 
 ######################################################################
 RECONNECT_CHECK([nothing happens if not enabled],
diff --git a/tests/test-daemon.py b/tests/test-daemon.py
new file mode 100644
index 000000000..3c757f308
--- /dev/null
+++ b/tests/test-daemon.py
@@ -0,0 +1,66 @@
+# Copyright (c) 2010 Nicira Networks.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import getopt
+import sys
+import time
+
+import ovs.daemon
+import ovs.util
+
+def main(argv):
+    try:
+        options, args = getopt.gnu_getopt(
+            argv[1:], 'b', ["bail", "help"] + ovs.daemon.LONG_OPTIONS)
+    except getopt.GetoptError, geo:
+        sys.stderr.write("%s: %s\n" % (ovs.util.PROGRAM_NAME, geo.msg))
+        sys.exit(1)
+
+    bail = False
+    for key, value in options:
+        if key == '--help':
+            usage()
+        elif key in ['-b', '--bail']:
+            bail = True
+        elif not ovs.daemon.parse_opt(key, value):
+            sys.stderr.write("%s: unhandled option %s\n"
+                             % (ovs.util.PROGRAM_NAME, key))
+            sys.exit(1)
+
+    ovs.daemon.die_if_already_running()
+    ovs.daemon.daemonize_start()
+    if bail:
+        sys.stderr.write("%s: exiting after daemonize_start() as requested\n"
+                         % ovs.util.PROGRAM_NAME)
+        sys.exit(1)
+    ovs.daemon.daemonize_complete()
+
+    while True:
+        time.sleep(1)
+
+def usage():
+    sys.stdout.write("""\
+%s: Open vSwitch daemonization test program for Python
+usage: %s [OPTIONS]
+""" % ovs.util.PROGRAM_NAME)
+    ovs.daemon.usage()
+    sys.stdout.write("""
+Other options:
+  -h, --help              display this help message
+  -b, --bail              exit with an error after daemonize_start()
+""")
+    sys.exit(0)
+
+if __name__ == '__main__':
+    main(sys.argv)
diff --git a/tests/test-json.py b/tests/test-json.py
new file mode 100644
index 000000000..bffb88a03
--- /dev/null
+++ b/tests/test-json.py
@@ -0,0 +1,92 @@
+# Copyright (c) 2009, 2010 Nicira Networks.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import codecs
+import getopt
+import sys
+
+import ovs.json
+
+def print_json(json):
+    if type(json) in [str, unicode]:
+        print "error: %s" % json
+        return False
+    else:
+        ovs.json.to_stream(json, sys.stdout)
+        sys.stdout.write("\n")
+        return True
+
+def parse_multiple(stream):
+    buf = stream.read(4096)
+    ok = True
+    parser = None
+    while len(buf):
+        if parser is None and buf[0] in " \t\r\n":
+            buf = buf[1:]
+        else:
+            if parser is None:
+                parser = ovs.json.Parser()
+            n = parser.feed(buf)
+            buf = buf[n:]
+            if len(buf):
+                if not print_json(parser.finish()):
+                    ok = False
+                parser = None
+        if len(buf) == 0:
+            buf = stream.read(4096)
+    if parser and not print_json(parser.finish()):
+        ok = False
+    return ok
+
+def main(argv):
+    argv0 = argv[0]
+
+    # Make stdout and stderr UTF-8, even if they are redirected to a file.
+    sys.stdout = codecs.getwriter("utf-8")(sys.stdout)
+    sys.stderr = codecs.getwriter("utf-8")(sys.stderr)
+
+    try:
+        options, args = getopt.gnu_getopt(argv[1:], '', ['multiple'])
+    except getopt.GetoptError, geo:
+        sys.stderr.write("%s: %s\n" % (argv0, geo.msg))
+        sys.exit(1)
+
+    multiple = False
+    for key, value in options:
+        if key == '--multiple':
+            multiple = True
+        else:
+            sys.stderr.write("%s: unhandled option %s\n" % (argv0, key))
+            sys.exit(1)
+
+    if len(args) != 1:
+        sys.stderr.write("usage: %s [--multiple] INPUT.json\n" % argv0)
+        sys.exit(1)
+
+    input_file = args[0]
+    if input_file == "-":
+        stream = sys.stdin
+    else:
+        stream = open(input_file, "r")
+
+    if multiple:
+        ok = parse_multiple(stream)
+    else:
+        ok = print_json(ovs.json.from_stream(stream))
+
+    if not ok:
+        sys.exit(1)
+
+if __name__ == '__main__':
+    main(sys.argv)
diff --git a/tests/test-jsonrpc.c b/tests/test-jsonrpc.c
index f2d0568ed..e8edec064 100644
--- a/tests/test-jsonrpc.c
+++ b/tests/test-jsonrpc.c
@@ -319,7 +319,7 @@ do_notify(int argc OVS_UNUSED, char *argv[])
 
     error = jsonrpc_send_block(rpc, msg);
     if (error) {
-        ovs_fatal(error, "could not send request");
+        ovs_fatal(error, "could not send notification");
     }
     jsonrpc_close(rpc);
 }
diff --git a/tests/test-jsonrpc.py b/tests/test-jsonrpc.py
new file mode 100644
index 000000000..a8bf553e2
--- /dev/null
+++ b/tests/test-jsonrpc.py
@@ -0,0 +1,221 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+import getopt
+import os
+import sys
+
+import ovs.daemon
+import ovs.json
+import ovs.jsonrpc
+import ovs.poller
+import ovs.stream
+
+def handle_rpc(rpc, msg):
+    done = False
+    reply = None
+
+    if msg.type == ovs.jsonrpc.Message.T_REQUEST:
+        if msg.method == "echo":
+            reply = ovs.jsonrpc.Message.create_reply(msg.params, msg.id)
+        else:
+            reply = ovs.jsonrpc.Message.create_error(
+                {"error": "unknown method"}, msg.id)
+            sys.stderr.write("unknown request %s" % msg.method)
+    elif msg.type == ovs.jsonrpc.Message.T_NOTIFY:
+        if msg.method == "shutdown":
+            done = True
+        else:
+            rpc.error(errno.ENOTTY)
+            sys.stderr.write("unknown notification %s" % msg.method)
+    else:
+        rpc.error(errno.EPROTO)
+        sys.stderr.write("unsolicited JSON-RPC reply or error\n")
+        
+    if reply:
+        rpc.send(reply)
+    return done
+
+def do_listen(name):
+    ovs.daemon.die_if_already_running()
+
+    error, pstream = ovs.stream.PassiveStream.open(name)
+    if error:
+        sys.stderr.write("could not listen on \"%s\": %s\n"
+                         % (name, os.strerror(error)))
+        sys.exit(1)
+
+    ovs.daemon.daemonize()
+
+    rpcs = []
+    done = False
+    while True:
+        # Accept new connections.
+        error, stream = pstream.accept()
+        if stream:
+            rpcs.append(ovs.jsonrpc.Connection(stream))
+        elif error != errno.EAGAIN:
+            sys.stderr.write("PassiveStream.accept() failed\n")
+            sys.exit(1)
+
+        # Service existing connections.
+        dead_rpcs = []
+        for rpc in rpcs:
+            rpc.run()
+
+            error = 0
+            if not rpc.get_backlog():
+                error, msg = rpc.recv()
+                if not error:
+                    if handle_rpc(rpc, msg):
+                        done = True
+
+            error = rpc.get_status()
+            if error:
+                rpc.close()
+                dead_rpcs.append(rpc)
+        rpcs = [rpc for rpc in rpcs if not rpc in dead_rpcs]
+
+        if done and not rpcs:
+            break
+
+        poller = ovs.poller.Poller()
+        pstream.wait(poller)
+        for rpc in rpcs:
+            rpc.wait(poller)
+            if not rpc.get_backlog():
+                rpc.recv_wait(poller)
+        poller.block()
+    pstream.close()
+
+def do_request(name, method, params_string):
+    params = ovs.json.from_string(params_string)
+    msg = ovs.jsonrpc.Message.create_request(method, params)
+    s = msg.is_valid()
+    if s:
+        sys.stderr.write("not a valid JSON-RPC request: %s\n" % s)
+        sys.exit(1)
+
+    error, stream = ovs.stream.Stream.open_block(ovs.stream.Stream.open(name))
+    if error:
+        sys.stderr.write("could not open \"%s\": %s\n"
+                         % (name, os.strerror(error)))
+        sys.exit(1)
+
+    rpc = ovs.jsonrpc.Connection(stream)
+
+    error = rpc.send(msg)
+    if error:
+        sys.stderr.write("could not send request: %s\n" % os.strerror(error))
+        sys.exit(1)
+
+    error, msg = rpc.recv_block()
+    if error:
+        sys.stderr.write("error waiting for reply: %s\n" % os.strerror(error))
+        sys.exit(1)
+    
+    print ovs.json.to_string(msg.to_json())
+
+    rpc.close()
+    
+def do_notify(name, method, params_string):
+    params = ovs.json.from_string(params_string)
+    msg = ovs.jsonrpc.Message.create_notify(method, params)
+    s = msg.is_valid()
+    if s:
+        sys.stderr.write("not a valid JSON-RPC notification: %s\n" % s)
+        sys.exit(1)
+
+    error, stream = ovs.stream.Stream.open_block(ovs.stream.Stream.open(name))
+    if error:
+        sys.stderr.write("could not open \"%s\": %s\n"
+                         % (name, os.strerror(error)))
+        sys.exit(1)
+
+    rpc = ovs.jsonrpc.Connection(stream)
+
+    error = rpc.send_block(msg)
+    if error:
+        sys.stderr.write("could not send notification: %s\n"
+                         % os.strerror(error))
+        sys.exit(1)
+
+    rpc.close()
+
+def main(argv):
+    try:
+        options, args = getopt.gnu_getopt(
+            argv[1:], 'h', ["help"] + ovs.daemon.LONG_OPTIONS)
+    except getopt.GetoptError, geo:
+        sys.stderr.write("%s: %s\n" % (ovs.util.PROGRAM_NAME, geo.msg))
+        sys.exit(1)
+
+    for key, value in options:
+        if key in ['h', '--help']:
+            usage()
+        elif not ovs.daemon.parse_opt(key, value):
+            sys.stderr.write("%s: unhandled option %s\n"
+                             % (ovs.util.PROGRAM_NAME, key))
+            sys.exit(1)
+
+    commands = {"listen": (do_listen, 1),
+                "request": (do_request, 3),
+                "notify": (do_notify, 3),
+                "help": (usage, (0,))}
+
+    command_name = args[0]
+    args = args[1:]
+    if not command_name in commands:
+        sys.stderr.write("%s: unknown command \"%s\" "
+                         "(use --help for help)\n" % (argv0, command_name))
+        sys.exit(1)
+
+    func, n_args = commands[command_name]
+    if type(n_args) == tuple:
+        if len(args) < n_args[0]:
+            sys.stderr.write("%s: \"%s\" requires at least %d arguments but "
+                             "only %d provided\n"
+                             % (argv0, command_name, n_args, len(args)))
+            sys.exit(1)
+    elif type(n_args) == int:
+        if len(args) != n_args:
+            sys.stderr.write("%s: \"%s\" requires %d arguments but %d "
+                             "provided\n"
+                             % (argv0, command_name, n_args, len(args)))
+            sys.exit(1)
+    else:
+        assert False
+
+    func(*args)
+
+def usage():
+    sys.stdout.write("""\
+%s: JSON-RPC test utility for Python
+usage: %s [OPTIONS] COMMAND [ARG...]
+  listen LOCAL             listen for connections on LOCAL
+  request REMOTE METHOD PARAMS   send request, print reply
+  notify REMOTE METHOD PARAMS  send notification and exit
+""" % (ovs.util.PROGRAM_NAME, ovs.util.PROGRAM_NAME))
+    ovs.stream.usage("JSON-RPC", True, True, True)
+    ovs.daemon.usage()
+    sys.stdout.write("""
+Other options:
+  -h, --help              display this help message
+""")
+    sys.exit(0)
+
+if __name__ == '__main__':
+    main(sys.argv)
+
diff --git a/tests/test-ovsdb.py b/tests/test-ovsdb.py
new file mode 100644
index 000000000..863bcb8fd
--- /dev/null
+++ b/tests/test-ovsdb.py
@@ -0,0 +1,372 @@
+# Copyright (c) 2009, 2010 Nicira Networks
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import codecs
+import getopt
+import re
+import os
+import signal
+import sys
+
+from ovs.db import error
+import ovs.db.idl
+import ovs.db.schema
+from ovs.db import data
+from ovs.db import types
+import ovs.ovsuuid
+import ovs.poller
+import ovs.util
+
+def unbox_json(json):
+    if type(json) == list and len(json) == 1:
+        return json[0]
+    else:
+        return json
+
+def do_default_atoms():
+    for type in types.ATOMIC_TYPES:
+        if type == types.VoidType:
+            continue
+
+        sys.stdout.write("%s: " % type.to_string())
+
+        atom = data.Atom.default(type)
+        if atom != data.Atom.default(type):
+            sys.stdout.write("wrong\n")
+            sys.exit(1)
+
+        sys.stdout.write("OK\n")
+
+def do_default_data():
+    any_errors = False
+    for n_min in 0, 1:
+        for key in types.ATOMIC_TYPES:
+            if key == types.VoidType:
+                continue
+            for value in types.ATOMIC_TYPES:
+                if value == types.VoidType:
+                    valueBase = None
+                else:
+                    valueBase = types.BaseType(value)
+                type = types.Type(types.BaseType(key), valueBase, n_min, 1)
+                assert type.is_valid()
+
+                sys.stdout.write("key %s, value %s, n_min %d: "
+                                 % (key.to_string(), value.to_string(), n_min))
+
+                datum = data.Datum.default(type)
+                if datum != data.Datum.default(type):
+                    sys.stdout.write("wrong\n")
+                    any_errors = True
+                else:
+                    sys.stdout.write("OK\n")
+    if any_errors:
+        sys.exit(1)
+
+def do_parse_atomic_type(type_string):
+    type_json = unbox_json(ovs.json.from_string(type_string))
+    atomic_type = types.AtomicType.from_json(type_json)
+    print ovs.json.to_string(atomic_type.to_json(), sort_keys=True)
+
+def do_parse_base_type(type_string):
+    type_json = unbox_json(ovs.json.from_string(type_string))
+    base_type = types.BaseType.from_json(type_json)
+    print ovs.json.to_string(base_type.to_json(), sort_keys=True)
+
+def do_parse_type(type_string):
+    type_json = unbox_json(ovs.json.from_string(type_string))
+    type = types.Type.from_json(type_json)
+    print ovs.json.to_string(type.to_json(), sort_keys=True)
+
+def do_parse_atoms(type_string, *atom_strings):
+    type_json = unbox_json(ovs.json.from_string(type_string))
+    base = types.BaseType.from_json(type_json)
+    for atom_string in atom_strings:
+        atom_json = unbox_json(ovs.json.from_string(atom_string))
+        try:
+            atom = data.Atom.from_json(base, atom_json)
+            print ovs.json.to_string(atom.to_json())
+        except error.Error, e:
+            print e
+
+def do_parse_data(type_string, *data_strings):
+    type_json = unbox_json(ovs.json.from_string(type_string))
+    type = types.Type.from_json(type_json)
+    for datum_string in data_strings:
+        datum_json = unbox_json(ovs.json.from_string(datum_string))
+        datum = data.Datum.from_json(type, datum_json)
+        print ovs.json.to_string(datum.to_json())
+
+def do_sort_atoms(type_string, atom_strings):
+    type_json = unbox_json(ovs.json.from_string(type_string))
+    base = types.BaseType.from_json(type_json)
+    atoms = [data.Atom.from_json(base, atom_json)
+             for atom_json in unbox_json(ovs.json.from_string(atom_strings))]
+    print ovs.json.to_string([data.Atom.to_json(atom)
+                              for atom in sorted(atoms)])
+
+def do_parse_column(name, column_string):
+    column_json = unbox_json(ovs.json.from_string(column_string))
+    column = ovs.db.schema.ColumnSchema.from_json(column_json, name)
+    print ovs.json.to_string(column.to_json(), sort_keys=True)
+
+def do_parse_table(name, table_string):
+    table_json = unbox_json(ovs.json.from_string(table_string))
+    table = ovs.db.schema.TableSchema.from_json(table_json, name)
+    print ovs.json.to_string(table.to_json(), sort_keys=True)
+
+def do_parse_rows(table_string, *rows):
+    table_json = unbox_json(ovs.json.from_string(table_string))
+    table = ovs.db.schema.TableSchema.from_json(table_json, name)
+
+def do_parse_schema(schema_string):
+    schema_json = unbox_json(ovs.json.from_string(schema_string))
+    schema = ovs.db.schema.DbSchema.from_json(schema_json)
+    print ovs.json.to_string(schema.to_json(), sort_keys=True)
+
+def print_idl(idl, step):
+    n = 0
+    for uuid, row in idl.data["simple"].iteritems():
+        s = ("%03d: i=%s r=%s b=%s s=%s u=%s "
+             "ia=%s ra=%s ba=%s sa=%s ua=%s uuid=%s"
+             % (step, row.i, row.r, row.b, row.s, row.u,
+                row.ia, row.ra, row.ba, row.sa, row.ua, uuid))
+        print(re.sub('""|,', "", s))
+        n += 1
+    if not n:
+        print("%03d: empty" % step)
+
+def substitute_uuids(json, symtab):
+    if type(json) in [str, unicode]:
+        symbol = symtab.get(json)
+        if symbol:
+            return str(symbol)
+    elif type(json) == list:
+        return [substitute_uuids(element, symtab) for element in json]
+    elif type(json) == dict:
+        d = {}
+        for key, value in json.iteritems():
+            d[key] = substitute_uuids(value, symtab)
+        return d
+    return json
+
+def parse_uuids(json, symtab):
+    if type(json) in [str, unicode] and ovs.ovsuuid.UUID.is_valid_string(json):
+        name = "#%d#" % len(symtab)
+        sys.stderr.write("%s = %s\n" % (name, json))
+        symtab[name] = json
+    elif type(json) == list:
+        for element in json:
+            parse_uuids(element, symtab)
+    elif type(json) == dict:
+        for value in json.itervalues():
+            parse_uuids(value, symtab)
+
+def do_idl(remote, *commands):
+    idl = ovs.db.idl.Idl(remote, "idltest")
+
+    if commands:
+        error, stream = ovs.stream.Stream.open_block(
+            ovs.stream.Stream.open(remote))
+        if error:
+            sys.stderr.write("failed to connect to \"%s\"" % remote)
+            sys.exit(1)
+        rpc = ovs.jsonrpc.Connection(stream)
+    else:
+        rpc = None
+
+    symtab = {}
+    seqno = 0
+    step = 0
+    for command in commands:
+        if command.startswith("+"):
+            # The previous transaction didn't change anything.
+            command = command[1:]
+        else:
+            # Wait for update.
+            while idl.get_seqno() == seqno and not idl.run():
+                rpc.run()
+
+                poller = ovs.poller.Poller()
+                idl.wait(poller)
+                rpc.wait(poller)
+                poller.block()
+                
+            print_idl(idl, step)
+            step += 1
+
+        seqno = idl.get_seqno()
+
+        if command == "reconnect":
+            print("%03d: reconnect" % step)
+            step += 1
+            idl.force_reconnect()
+        elif not command.startswith("["):
+            idl_set(idl, command, step)
+            step += 1
+        else:
+            json = ovs.json.from_string(command)
+            if type(json) in [str, unicode]:
+                sys.stderr.write("\"%s\": %s\n" % (command, json))
+                sys.exit(1)
+            json = substitute_uuids(json, symtab)
+            request = ovs.jsonrpc.Message.create_request("transact", json)
+            error, reply = rpc.transact_block(request)
+            if error:
+                sys.stderr.write("jsonrpc transaction failed: %s"
+                                 % os.strerror(error))
+                sys.exit(1)
+            sys.stdout.write("%03d: " % step)
+            sys.stdout.flush()
+            step += 1
+            if reply.result is not None:
+                parse_uuids(reply.result, symtab)
+            reply.id = None
+            sys.stdout.write("%s\n" % ovs.json.to_string(reply.to_json()))
+
+    if rpc:
+        rpc.close()
+    while idl.get_seqno() == seqno and not idl.run():
+        poller = ovs.poller.Poller()
+        idl.wait(poller)
+        poller.block()
+    print_idl(idl, step)
+    step += 1
+    idl.close()
+    print("%03d: done" % step)
+
+def usage():
+    print """\
+%(program_name)s: test utility for Open vSwitch database Python bindings
+usage: %(program_name)s [OPTIONS] COMMAND ARG...
+
+The following commands are supported:
+default-atoms
+  test ovsdb_atom_default()
+default-data
+  test ovsdb_datum_default()
+parse-atomic-type TYPE
+  parse TYPE as OVSDB atomic type, and re-serialize
+parse-base-type TYPE
+  parse TYPE as OVSDB base type, and re-serialize
+parse-type JSON
+  parse JSON as OVSDB type, and re-serialize
+parse-atoms TYPE ATOM...
+  parse JSON ATOMs as atoms of TYPE, and re-serialize
+parse-atom-strings TYPE ATOM...
+  parse string ATOMs as atoms of given TYPE, and re-serialize
+sort-atoms TYPE ATOM...
+  print JSON ATOMs in sorted order
+parse-data TYPE DATUM...
+  parse JSON DATUMs as data of given TYPE, and re-serialize
+parse-column NAME OBJECT
+  parse column NAME with info OBJECT, and re-serialize
+parse-table NAME OBJECT
+  parse table NAME with info OBJECT
+parse-schema JSON
+  parse JSON as an OVSDB schema, and re-serialize
+idl SERVER [TRANSACTION...]
+  connect to SERVER and dump the contents of the database
+  as seen initially by the IDL implementation and after
+  executing each TRANSACTION.  (Each TRANSACTION must modify
+  the database or this command will hang.)
+
+The following options are also available:
+  -t, --timeout=SECS          give up after SECS seconds
+  -h, --help                  display this help message\
+""" % {'program_name': ovs.util.PROGRAM_NAME}
+    sys.exit(0)
+
+def main(argv):
+    # Make stdout and stderr UTF-8, even if they are redirected to a file.
+    sys.stdout = codecs.getwriter("utf-8")(sys.stdout)
+    sys.stderr = codecs.getwriter("utf-8")(sys.stderr)
+
+    try:
+        options, args = getopt.gnu_getopt(argv[1:], 't:h',
+                                          ['timeout',
+                                           'help'])
+    except getopt.GetoptError, geo:
+        sys.stderr.write("%s: %s\n" % (ovs.util.PROGRAM_NAME, geo.msg))
+        sys.exit(1)
+
+    for key, value in options:
+        if key in ['-h', '--help']:
+            usage()
+        elif key in ['-t', '--timeout']:
+            try:
+                timeout = int(value)
+                if timeout < 1:
+                    raise TypeError
+            except TypeError:
+                raise error.Error("value %s on -t or --timeout is not at "
+                                  "least 1" % value)
+            signal.alarm(timeout)
+        else:
+            sys.exit(0)
+
+    optKeys = [key for key, value in options]
+
+    if not args:
+        sys.stderr.write("%s: missing command argument "
+                         "(use --help for help)\n" % ovs.util.PROGRAM_NAME)
+        sys.exit(1)
+
+    commands = {"default-atoms": (do_default_atoms, 0),
+                "default-data": (do_default_data, 0),
+                "parse-atomic-type": (do_parse_atomic_type, 1),
+                "parse-base-type": (do_parse_base_type, 1),
+                "parse-type": (do_parse_type, 1),
+                "parse-atoms": (do_parse_atoms, (2,)),
+                "parse-data": (do_parse_data, (2,)),
+                "sort-atoms": (do_sort_atoms, 2),
+                "parse-column": (do_parse_column, 2),
+                "parse-table": (do_parse_table, 2),
+                "parse-schema": (do_parse_schema, 1),
+                "idl": (do_idl, (1,))}
+
+    command_name = args[0]
+    args = args[1:]
+    if not command_name in commands:
+        sys.stderr.write("%s: unknown command \"%s\" "
+                         "(use --help for help)\n" % (ovs.util.PROGRAM_NAME,
+                                                      command_name))
+        sys.exit(1)
+
+    func, n_args = commands[command_name]
+    if type(n_args) == tuple:
+        if len(args) < n_args[0]:
+            sys.stderr.write("%s: \"%s\" requires at least %d arguments but "
+                             "only %d provided\n"
+                             % (ovs.util.PROGRAM_NAME, command_name,
+                                n_args, len(args)))
+            sys.exit(1)
+    elif type(n_args) == int:
+        if len(args) != n_args:
+            sys.stderr.write("%s: \"%s\" requires %d arguments but %d "
+                             "provided\n"
+                             % (ovs.util.PROGRAM_NAME, command_name,
+                                n_args, len(args)))
+            sys.exit(1)
+    else:
+        assert False
+
+    func(*args)
+
+if __name__ == '__main__':
+    try:
+        main(sys.argv)
+    except error.Error, e:
+        sys.stderr.write("%s\n" % e)
+        sys.exit(1)
diff --git a/tests/test-reconnect.py b/tests/test-reconnect.py
new file mode 100644
index 000000000..4b483db09
--- /dev/null
+++ b/tests/test-reconnect.py
@@ -0,0 +1,195 @@
+# Copyright (c) 2009, 2010 Nicira Networks.
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+# 
+#     http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import errno
+import logging
+import sys
+
+import ovs.reconnect
+
+def do_enable(arg):
+    r.enable(now)
+
+def do_disable(arg):
+    r.disable(now)
+
+def do_force_reconnect(arg):
+    r.force_reconnect(now)
+
+def error_from_string(s):
+    if not s:
+        return 0
+    elif s == "ECONNREFUSED":
+        return errno.ECONNREFUSED
+    elif s == "EOF":
+        return EOF
+    else:
+        sys.stderr.write("unknown error '%s'\n" % s)
+        sys.exit(1)
+
+def do_disconnected(arg):
+    r.disconnected(now, error_from_string(arg))
+    
+def do_connecting(arg):
+    r.connecting(now)
+
+def do_connect_failed(arg):
+    r.connect_failed(now, error_from_string(arg))
+
+def do_connected(arg):
+    r.connected(now)
+
+def do_received(arg):
+    r.received(now)
+
+def do_run(arg):
+    global now
+    if arg is not None:
+        now += int(arg)
+
+    action = r.run(now)
+    if action is None:
+        pass
+    elif action == ovs.reconnect.CONNECT:
+        print "  should connect"
+    elif action == ovs.reconnect.DISCONNECT:
+        print "  should disconnect"
+    elif action == ovs.reconnect.PROBE:
+        print "  should send probe"
+    else:
+        assert False
+
+def do_advance(arg):
+    global now
+    now += int(arg)
+
+def do_timeout(arg):
+    global now
+    timeout = r.timeout(now)
+    if timeout >= 0:
+        print "  advance %d ms" % timeout
+        now += timeout
+    else:
+        print "  no timeout"
+
+def do_set_max_tries(arg):
+    r.set_max_tries(int(arg))
+
+def diff_stats(old, new):
+    if (old.state != new.state or
+        old.state_elapsed != new.state_elapsed or
+        old.backoff != new.backoff):
+        print("  in %s for %d ms (%d ms backoff)"
+              % (new.state, new.state_elapsed, new.backoff))
+
+    if (old.creation_time != new.creation_time or
+        old.last_received != new.last_received or
+        old.last_connected != new.last_connected):
+        print("  created %d, last received %d, last connected %d"
+              % (new.creation_time, new.last_received, new.last_connected))
+
+    if (old.n_successful_connections != new.n_successful_connections or
+        old.n_attempted_connections != new.n_attempted_connections or
+        old.seqno != new.seqno):
+        print("  %d successful connections out of %d attempts, seqno %d"
+              % (new.n_successful_connections, new.n_attempted_connections,
+                 new.seqno))
+
+    if (old.is_connected != new.is_connected or
+        old.current_connection_duration != new.current_connection_duration or
+        old.total_connected_duration != new.total_connected_duration):
+        if new.is_connected:
+            negate = ""
+        else:
+            negate = "not "
+        print("  %sconnected (%d ms), total %d ms connected"
+              % (negate, new.current_connection_duration,
+                 new.total_connected_duration))
+
+def do_set_passive(arg):
+    r.set_passive(True, now)
+
+def do_listening(arg):
+    r.listening(now)
+
+def do_listen_error(arg):
+    r.listen_error(now, int(arg))
+
+def main():
+    commands = {
+        "enable": do_enable,
+        "disable": do_disable,
+        "force-reconnect": do_force_reconnect,
+        "disconnected": do_disconnected,
+        "connecting": do_connecting,
+        "connect-failed": do_connect_failed,
+        "connected": do_connected,
+        "received": do_received,
+        "run": do_run,
+        "advance": do_advance,
+        "timeout": do_timeout,
+        "set-max-tries": do_set_max_tries,
+        "passive": do_set_passive,
+        "listening": do_listening,
+        "listen-error": do_listen_error
+    }
+
+    logging.basicConfig(level=logging.CRITICAL)
+
+    global now
+    global r
+
+    now = 1000
+    r = ovs.reconnect.Reconnect(now)
+    r.set_name("remote")
+    prev = r.get_stats(now)
+    print "### t=%d ###" % now
+    old_time = now
+    old_max_tries = r.get_max_tries()
+    while True:
+        line = sys.stdin.readline()
+        if line == "":
+            break
+
+        print line[:-1]
+        if line[0] == "#":
+            continue
+
+        args = line.split()
+        if len(args) == 0:
+            continue
+
+        command = args[0]
+        if len(args) > 1:
+            op = args[1]
+        else:
+            op = None
+        commands[command](op)
+
+        if old_time != now:
+            print
+            print "### t=%d ###" % now
+            old_time = now
+
+        cur = r.get_stats(now)
+        diff_stats(prev, cur)
+        prev = cur
+        if r.get_max_tries() != old_max_tries:
+            old_max_tries = r.get_max_tries()
+            print "  %d tries left" % old_max_tries
+
+if __name__ == '__main__':
+    main()
+
+
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 2eab5814b..42e62dfbe 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -41,12 +41,14 @@ m4_include([tests/library.at])
 m4_include([tests/classifier.at])
 m4_include([tests/check-structs.at])
 m4_include([tests/daemon.at])
+m4_include([tests/daemon-py.at])
 m4_include([tests/vconn.at])
 m4_include([tests/dir_name.at])
 m4_include([tests/aes128.at])
 m4_include([tests/uuid.at])
 m4_include([tests/json.at])
 m4_include([tests/jsonrpc.at])
+m4_include([tests/jsonrpc-py.at])
 m4_include([tests/timeval.at])
 m4_include([tests/lockfile.at])
 m4_include([tests/reconnect.at])
diff --git a/xenserver/README b/xenserver/README
index 93be52619..3b7809fc3 100644
--- a/xenserver/README
+++ b/xenserver/README
@@ -74,6 +74,12 @@ files are:
 
         Open vSwitch-aware replacement for Citrix script of the same name.
 
+    uuid.py
+
+        This is uuid.py from Python 2.5.  It is installed into the
+        Open vSwitch RPM because XenServer 5.5 and 5.6 use Python 2.4,
+        which do not have uuid.py.
+
 To install, build the Open vSwitch RPM with a command like this:
 
         rpmbuild -D "openvswitch_version $full_version" \
diff --git a/xenserver/automake.mk b/xenserver/automake.mk
index b451bbb87..b16fef9be 100644
--- a/xenserver/automake.mk
+++ b/xenserver/automake.mk
@@ -24,4 +24,5 @@ EXTRA_DIST += \
 	xenserver/usr_sbin_brctl \
 	xenserver/usr_sbin_xen-bugtool \
 	xenserver/usr_share_openvswitch_scripts_refresh-network-uuids \
-	xenserver/usr_share_openvswitch_scripts_sysconfig.template
+	xenserver/usr_share_openvswitch_scripts_sysconfig.template \
+	xenserver/uuid.py
diff --git a/xenserver/openvswitch-xen.spec b/xenserver/openvswitch-xen.spec
index 9e1c9c29a..f693ea0db 100644
--- a/xenserver/openvswitch-xen.spec
+++ b/xenserver/openvswitch-xen.spec
@@ -88,6 +88,7 @@ install -m 644 \
 
 install -d -m 755 $RPM_BUILD_ROOT/lib/modules/%{xen_version}/kernel/extra/openvswitch
 find datapath/linux-2.6 -name *.ko -exec install -m 755  \{\} $RPM_BUILD_ROOT/lib/modules/%{xen_version}/kernel/extra/openvswitch \;
+install xenserver/uuid.py $RPM_BUILD_ROOT/usr/share/openvswitch/python
 
 # Get rid of stuff we don't want to make RPM happy.
 rm \
@@ -367,6 +368,28 @@ fi
 /etc/profile.d/openvswitch.sh
 /lib/modules/%{xen_version}/kernel/extra/openvswitch/openvswitch_mod.ko
 /lib/modules/%{xen_version}/kernel/extra/openvswitch/brcompat_mod.ko
+/usr/share/openvswitch/python/ovs/__init__.py
+/usr/share/openvswitch/python/ovs/daemon.py
+/usr/share/openvswitch/python/ovs/db/__init__.py
+/usr/share/openvswitch/python/ovs/db/data.py
+/usr/share/openvswitch/python/ovs/db/error.py
+/usr/share/openvswitch/python/ovs/db/idl.py
+/usr/share/openvswitch/python/ovs/db/parser.py
+/usr/share/openvswitch/python/ovs/db/schema.py
+/usr/share/openvswitch/python/ovs/db/types.py
+/usr/share/openvswitch/python/ovs/dirs.py
+/usr/share/openvswitch/python/ovs/fatal_signal.py
+/usr/share/openvswitch/python/ovs/json.py
+/usr/share/openvswitch/python/ovs/jsonrpc.py
+/usr/share/openvswitch/python/ovs/ovsuuid.py
+/usr/share/openvswitch/python/ovs/poller.py
+/usr/share/openvswitch/python/ovs/process.py
+/usr/share/openvswitch/python/ovs/reconnect.py
+/usr/share/openvswitch/python/ovs/socket_util.py
+/usr/share/openvswitch/python/ovs/stream.py
+/usr/share/openvswitch/python/ovs/timeval.py
+/usr/share/openvswitch/python/ovs/util.py
+/usr/share/openvswitch/python/uuid.py
 /usr/share/openvswitch/scripts/refresh-network-uuids
 /usr/share/openvswitch/scripts/interface-reconfigure
 /usr/share/openvswitch/scripts/InterfaceReconfigure.py
@@ -399,7 +422,8 @@ fi
 /usr/share/man/man8/ovs-vsctl.8.gz
 /usr/share/man/man8/ovs-vswitchd.8.gz
 /var/lib/openvswitch
-%exclude /usr/lib/xsconsole/plugins-base/*.pyc
-%exclude /usr/lib/xsconsole/plugins-base/*.pyo
-%exclude /usr/share/openvswitch/scripts/*.pyc
-%exclude /usr/share/openvswitch/scripts/*.pyo
+%exclude /usr/lib/xsconsole/plugins-base/*.py[co]
+%exclude /usr/share/openvswitch/scripts/*.py[co]
+%exclude /usr/share/openvswitch/python/*.py[co]
+%exclude /usr/share/openvswitch/python/ovs/*.py[co]
+%exclude /usr/share/openvswitch/python/ovs/db/*.py[co]
diff --git a/xenserver/uuid.py b/xenserver/uuid.py
new file mode 100644
index 000000000..ae3da25ca
--- /dev/null
+++ b/xenserver/uuid.py
@@ -0,0 +1,541 @@
+r"""UUID objects (universally unique identifiers) according to RFC 4122.
+
+This module provides immutable UUID objects (class UUID) and the functions
+uuid1(), uuid3(), uuid4(), uuid5() for generating version 1, 3, 4, and 5
+UUIDs as specified in RFC 4122.
+
+If all you want is a unique ID, you should probably call uuid1() or uuid4().
+Note that uuid1() may compromise privacy since it creates a UUID containing
+the computer's network address.  uuid4() creates a random UUID.
+
+Typical usage:
+
+    >>> import uuid
+
+    # make a UUID based on the host ID and current time
+    >>> uuid.uuid1()
+    UUID('a8098c1a-f86e-11da-bd1a-00112444be1e')
+
+    # make a UUID using an MD5 hash of a namespace UUID and a name
+    >>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org')
+    UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e')
+
+    # make a random UUID
+    >>> uuid.uuid4()
+    UUID('16fd2706-8baf-433b-82eb-8c7fada847da')
+
+    # make a UUID using a SHA-1 hash of a namespace UUID and a name
+    >>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org')
+    UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d')
+
+    # make a UUID from a string of hex digits (braces and hyphens ignored)
+    >>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}')
+
+    # convert a UUID to a string of hex digits in standard form
+    >>> str(x)
+    '00010203-0405-0607-0809-0a0b0c0d0e0f'
+
+    # get the raw 16 bytes of the UUID
+    >>> x.bytes
+    '\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'
+
+    # make a UUID from a 16-byte string
+    >>> uuid.UUID(bytes=x.bytes)
+    UUID('00010203-0405-0607-0809-0a0b0c0d0e0f')
+"""
+
+__author__ = 'Ka-Ping Yee <ping@zesty.ca>'
+
+RESERVED_NCS, RFC_4122, RESERVED_MICROSOFT, RESERVED_FUTURE = [
+    'reserved for NCS compatibility', 'specified in RFC 4122',
+    'reserved for Microsoft compatibility', 'reserved for future definition']
+
+class UUID(object):
+    """Instances of the UUID class represent UUIDs as specified in RFC 4122.
+    UUID objects are immutable, hashable, and usable as dictionary keys.
+    Converting a UUID to a string with str() yields something in the form
+    '12345678-1234-1234-1234-123456789abc'.  The UUID constructor accepts
+    five possible forms: a similar string of hexadecimal digits, or a tuple
+    of six integer fields (with 32-bit, 16-bit, 16-bit, 8-bit, 8-bit, and
+    48-bit values respectively) as an argument named 'fields', or a string
+    of 16 bytes (with all the integer fields in big-endian order) as an
+    argument named 'bytes', or a string of 16 bytes (with the first three
+    fields in little-endian order) as an argument named 'bytes_le', or a
+    single 128-bit integer as an argument named 'int'.
+
+    UUIDs have these read-only attributes:
+
+        bytes       the UUID as a 16-byte string (containing the six
+                    integer fields in big-endian byte order)
+
+        bytes_le    the UUID as a 16-byte string (with time_low, time_mid,
+                    and time_hi_version in little-endian byte order)
+
+        fields      a tuple of the six integer fields of the UUID,
+                    which are also available as six individual attributes
+                    and two derived attributes:
+
+            time_low                the first 32 bits of the UUID
+            time_mid                the next 16 bits of the UUID
+            time_hi_version         the next 16 bits of the UUID
+            clock_seq_hi_variant    the next 8 bits of the UUID
+            clock_seq_low           the next 8 bits of the UUID
+            node                    the last 48 bits of the UUID
+
+            time                    the 60-bit timestamp
+            clock_seq               the 14-bit sequence number
+
+        hex         the UUID as a 32-character hexadecimal string
+
+        int         the UUID as a 128-bit integer
+
+        urn         the UUID as a URN as specified in RFC 4122
+
+        variant     the UUID variant (one of the constants RESERVED_NCS,
+                    RFC_4122, RESERVED_MICROSOFT, or RESERVED_FUTURE)
+
+        version     the UUID version number (1 through 5, meaningful only
+                    when the variant is RFC_4122)
+    """
+
+    def __init__(self, hex=None, bytes=None, bytes_le=None, fields=None,
+                       int=None, version=None):
+        r"""Create a UUID from either a string of 32 hexadecimal digits,
+        a string of 16 bytes as the 'bytes' argument, a string of 16 bytes
+        in little-endian order as the 'bytes_le' argument, a tuple of six
+        integers (32-bit time_low, 16-bit time_mid, 16-bit time_hi_version,
+        8-bit clock_seq_hi_variant, 8-bit clock_seq_low, 48-bit node) as
+        the 'fields' argument, or a single 128-bit integer as the 'int'
+        argument.  When a string of hex digits is given, curly braces,
+        hyphens, and a URN prefix are all optional.  For example, these
+        expressions all yield the same UUID:
+
+        UUID('{12345678-1234-5678-1234-567812345678}')
+        UUID('12345678123456781234567812345678')
+        UUID('urn:uuid:12345678-1234-5678-1234-567812345678')
+        UUID(bytes='\x12\x34\x56\x78'*4)
+        UUID(bytes_le='\x78\x56\x34\x12\x34\x12\x78\x56' +
+                      '\x12\x34\x56\x78\x12\x34\x56\x78')
+        UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678))
+        UUID(int=0x12345678123456781234567812345678)
+
+        Exactly one of 'hex', 'bytes', 'bytes_le', 'fields', or 'int' must
+        be given.  The 'version' argument is optional; if given, the resulting
+        UUID will have its variant and version set according to RFC 4122,
+        overriding the given 'hex', 'bytes', 'bytes_le', 'fields', or 'int'.
+        """
+
+        if [hex, bytes, bytes_le, fields, int].count(None) != 4:
+            raise TypeError('need one of hex, bytes, bytes_le, fields, or int')
+        if hex is not None:
+            hex = hex.replace('urn:', '').replace('uuid:', '')
+            hex = hex.strip('{}').replace('-', '')
+            if len(hex) != 32:
+                raise ValueError('badly formed hexadecimal UUID string')
+            int = long(hex, 16)
+        if bytes_le is not None:
+            if len(bytes_le) != 16:
+                raise ValueError('bytes_le is not a 16-char string')
+            bytes = (bytes_le[3] + bytes_le[2] + bytes_le[1] + bytes_le[0] +
+                     bytes_le[5] + bytes_le[4] + bytes_le[7] + bytes_le[6] +
+                     bytes_le[8:])
+        if bytes is not None:
+            if len(bytes) != 16:
+                raise ValueError('bytes is not a 16-char string')
+            int = long(('%02x'*16) % tuple(map(ord, bytes)), 16)
+        if fields is not None:
+            if len(fields) != 6:
+                raise ValueError('fields is not a 6-tuple')
+            (time_low, time_mid, time_hi_version,
+             clock_seq_hi_variant, clock_seq_low, node) = fields
+            if not 0 <= time_low < 1<<32L:
+                raise ValueError('field 1 out of range (need a 32-bit value)')
+            if not 0 <= time_mid < 1<<16L:
+                raise ValueError('field 2 out of range (need a 16-bit value)')
+            if not 0 <= time_hi_version < 1<<16L:
+                raise ValueError('field 3 out of range (need a 16-bit value)')
+            if not 0 <= clock_seq_hi_variant < 1<<8L:
+                raise ValueError('field 4 out of range (need an 8-bit value)')
+            if not 0 <= clock_seq_low < 1<<8L:
+                raise ValueError('field 5 out of range (need an 8-bit value)')
+            if not 0 <= node < 1<<48L:
+                raise ValueError('field 6 out of range (need a 48-bit value)')
+            clock_seq = (clock_seq_hi_variant << 8L) | clock_seq_low
+            int = ((time_low << 96L) | (time_mid << 80L) |
+                   (time_hi_version << 64L) | (clock_seq << 48L) | node)
+        if int is not None:
+            if not 0 <= int < 1<<128L:
+                raise ValueError('int is out of range (need a 128-bit value)')
+        if version is not None:
+            if not 1 <= version <= 5:
+                raise ValueError('illegal version number')
+            # Set the variant to RFC 4122.
+            int &= ~(0xc000 << 48L)
+            int |= 0x8000 << 48L
+            # Set the version number.
+            int &= ~(0xf000 << 64L)
+            int |= version << 76L
+        self.__dict__['int'] = int
+
+    def __cmp__(self, other):
+        if isinstance(other, UUID):
+            return cmp(self.int, other.int)
+        return NotImplemented
+
+    def __hash__(self):
+        return hash(self.int)
+
+    def __int__(self):
+        return self.int
+
+    def __repr__(self):
+        return 'UUID(%r)' % str(self)
+
+    def __setattr__(self, name, value):
+        raise TypeError('UUID objects are immutable')
+
+    def __str__(self):
+        hex = '%032x' % self.int
+        return '%s-%s-%s-%s-%s' % (
+            hex[:8], hex[8:12], hex[12:16], hex[16:20], hex[20:])
+
+    def get_bytes(self):
+        bytes = ''
+        for shift in range(0, 128, 8):
+            bytes = chr((self.int >> shift) & 0xff) + bytes
+        return bytes
+
+    bytes = property(get_bytes)
+
+    def get_bytes_le(self):
+        bytes = self.bytes
+        return (bytes[3] + bytes[2] + bytes[1] + bytes[0] +
+                bytes[5] + bytes[4] + bytes[7] + bytes[6] + bytes[8:])
+
+    bytes_le = property(get_bytes_le)
+
+    def get_fields(self):
+        return (self.time_low, self.time_mid, self.time_hi_version,
+                self.clock_seq_hi_variant, self.clock_seq_low, self.node)
+
+    fields = property(get_fields)
+
+    def get_time_low(self):
+        return self.int >> 96L
+
+    time_low = property(get_time_low)
+
+    def get_time_mid(self):
+        return (self.int >> 80L) & 0xffff
+
+    time_mid = property(get_time_mid)
+
+    def get_time_hi_version(self):
+        return (self.int >> 64L) & 0xffff
+
+    time_hi_version = property(get_time_hi_version)
+
+    def get_clock_seq_hi_variant(self):
+        return (self.int >> 56L) & 0xff
+
+    clock_seq_hi_variant = property(get_clock_seq_hi_variant)
+
+    def get_clock_seq_low(self):
+        return (self.int >> 48L) & 0xff
+
+    clock_seq_low = property(get_clock_seq_low)
+
+    def get_time(self):
+        return (((self.time_hi_version & 0x0fffL) << 48L) |
+                (self.time_mid << 32L) | self.time_low)
+
+    time = property(get_time)
+
+    def get_clock_seq(self):
+        return (((self.clock_seq_hi_variant & 0x3fL) << 8L) |
+                self.clock_seq_low)
+
+    clock_seq = property(get_clock_seq)
+
+    def get_node(self):
+        return self.int & 0xffffffffffff
+
+    node = property(get_node)
+
+    def get_hex(self):
+        return '%032x' % self.int
+
+    hex = property(get_hex)
+
+    def get_urn(self):
+        return 'urn:uuid:' + str(self)
+
+    urn = property(get_urn)
+
+    def get_variant(self):
+        if not self.int & (0x8000 << 48L):
+            return RESERVED_NCS
+        elif not self.int & (0x4000 << 48L):
+            return RFC_4122
+        elif not self.int & (0x2000 << 48L):
+            return RESERVED_MICROSOFT
+        else:
+            return RESERVED_FUTURE
+
+    variant = property(get_variant)
+
+    def get_version(self):
+        # The version bits are only meaningful for RFC 4122 UUIDs.
+        if self.variant == RFC_4122:
+            return int((self.int >> 76L) & 0xf)
+
+    version = property(get_version)
+
+def _find_mac(command, args, hw_identifiers, get_index):
+    import os
+    for dir in ['', '/sbin/', '/usr/sbin']:
+        executable = os.path.join(dir, command)
+        if not os.path.exists(executable):
+            continue
+
+        try:
+            # LC_ALL to get English output, 2>/dev/null to
+            # prevent output on stderr
+            cmd = 'LC_ALL=C %s %s 2>/dev/null' % (executable, args)
+            pipe = os.popen(cmd)
+        except IOError:
+            continue
+
+        for line in pipe:
+            words = line.lower().split()
+            for i in range(len(words)):
+                if words[i] in hw_identifiers:
+                    return int(words[get_index(i)].replace(':', ''), 16)
+    return None
+
+def _ifconfig_getnode():
+    """Get the hardware address on Unix by running ifconfig."""
+
+    # This works on Linux ('' or '-a'), Tru64 ('-av'), but not all Unixes.
+    for args in ('', '-a', '-av'):
+        mac = _find_mac('ifconfig', args, ['hwaddr', 'ether'], lambda i: i+1)
+        if mac:
+            return mac
+
+    import socket
+    ip_addr = socket.gethostbyname(socket.gethostname())
+
+    # Try getting the MAC addr from arp based on our IP address (Solaris).
+    mac = _find_mac('arp', '-an', [ip_addr], lambda i: -1)
+    if mac:
+        return mac
+
+    # This might work on HP-UX.
+    mac = _find_mac('lanscan', '-ai', ['lan0'], lambda i: 0)
+    if mac:
+        return mac
+
+    return None
+
+def _ipconfig_getnode():
+    """Get the hardware address on Windows by running ipconfig.exe."""
+    import os, re
+    dirs = ['', r'c:\windows\system32', r'c:\winnt\system32']
+    try:
+        import ctypes
+        buffer = ctypes.create_string_buffer(300)
+        ctypes.windll.kernel32.GetSystemDirectoryA(buffer, 300)
+        dirs.insert(0, buffer.value.decode('mbcs'))
+    except:
+        pass
+    for dir in dirs:
+        try:
+            pipe = os.popen(os.path.join(dir, 'ipconfig') + ' /all')
+        except IOError:
+            continue
+        for line in pipe:
+            value = line.split(':')[-1].strip().lower()
+            if re.match('([0-9a-f][0-9a-f]-){5}[0-9a-f][0-9a-f]', value):
+                return int(value.replace('-', ''), 16)
+
+def _netbios_getnode():
+    """Get the hardware address on Windows using NetBIOS calls.
+    See http://support.microsoft.com/kb/118623 for details."""
+    import win32wnet, netbios
+    ncb = netbios.NCB()
+    ncb.Command = netbios.NCBENUM
+    ncb.Buffer = adapters = netbios.LANA_ENUM()
+    adapters._pack()
+    if win32wnet.Netbios(ncb) != 0:
+        return
+    adapters._unpack()
+    for i in range(adapters.length):
+        ncb.Reset()
+        ncb.Command = netbios.NCBRESET
+        ncb.Lana_num = ord(adapters.lana[i])
+        if win32wnet.Netbios(ncb) != 0:
+            continue
+        ncb.Reset()
+        ncb.Command = netbios.NCBASTAT
+        ncb.Lana_num = ord(adapters.lana[i])
+        ncb.Callname = '*'.ljust(16)
+        ncb.Buffer = status = netbios.ADAPTER_STATUS()
+        if win32wnet.Netbios(ncb) != 0:
+            continue
+        status._unpack()
+        bytes = map(ord, status.adapter_address)
+        return ((bytes[0]<<40L) + (bytes[1]<<32L) + (bytes[2]<<24L) +
+                (bytes[3]<<16L) + (bytes[4]<<8L) + bytes[5])
+
+# Thanks to Thomas Heller for ctypes and for his help with its use here.
+
+# If ctypes is available, use it to find system routines for UUID generation.
+_uuid_generate_random = _uuid_generate_time = _UuidCreate = None
+try:
+    import ctypes, ctypes.util
+    _buffer = ctypes.create_string_buffer(16)
+
+    # The uuid_generate_* routines are provided by libuuid on at least
+    # Linux and FreeBSD, and provided by libc on Mac OS X.
+    for libname in ['uuid', 'c']:
+        try:
+            lib = ctypes.CDLL(ctypes.util.find_library(libname))
+        except:
+            continue
+        if hasattr(lib, 'uuid_generate_random'):
+            _uuid_generate_random = lib.uuid_generate_random
+        if hasattr(lib, 'uuid_generate_time'):
+            _uuid_generate_time = lib.uuid_generate_time
+
+    # On Windows prior to 2000, UuidCreate gives a UUID containing the
+    # hardware address.  On Windows 2000 and later, UuidCreate makes a
+    # random UUID and UuidCreateSequential gives a UUID containing the
+    # hardware address.  These routines are provided by the RPC runtime.
+    # NOTE:  at least on Tim's WinXP Pro SP2 desktop box, while the last
+    # 6 bytes returned by UuidCreateSequential are fixed, they don't appear
+    # to bear any relationship to the MAC address of any network device
+    # on the box.
+    try:
+        lib = ctypes.windll.rpcrt4
+    except:
+        lib = None
+    _UuidCreate = getattr(lib, 'UuidCreateSequential',
+                          getattr(lib, 'UuidCreate', None))
+except:
+    pass
+
+def _unixdll_getnode():
+    """Get the hardware address on Unix using ctypes."""
+    _uuid_generate_time(_buffer)
+    return UUID(bytes=_buffer.raw).node
+
+def _windll_getnode():
+    """Get the hardware address on Windows using ctypes."""
+    if _UuidCreate(_buffer) == 0:
+        return UUID(bytes=_buffer.raw).node
+
+def _random_getnode():
+    """Get a random node ID, with eighth bit set as suggested by RFC 4122."""
+    import random
+    return random.randrange(0, 1<<48L) | 0x010000000000L
+
+_node = None
+
+def getnode():
+    """Get the hardware address as a 48-bit positive integer.
+
+    The first time this runs, it may launch a separate program, which could
+    be quite slow.  If all attempts to obtain the hardware address fail, we
+    choose a random 48-bit number with its eighth bit set to 1 as recommended
+    in RFC 4122.
+    """
+
+    global _node
+    if _node is not None:
+        return _node
+
+    import sys
+    if sys.platform == 'win32':
+        getters = [_windll_getnode, _netbios_getnode, _ipconfig_getnode]
+    else:
+        getters = [_unixdll_getnode, _ifconfig_getnode]
+
+    for getter in getters + [_random_getnode]:
+        try:
+            _node = getter()
+        except:
+            continue
+        if _node is not None:
+            return _node
+
+_last_timestamp = None
+
+def uuid1(node=None, clock_seq=None):
+    """Generate a UUID from a host ID, sequence number, and the current time.
+    If 'node' is not given, getnode() is used to obtain the hardware
+    address.  If 'clock_seq' is given, it is used as the sequence number;
+    otherwise a random 14-bit sequence number is chosen."""
+
+    # When the system provides a version-1 UUID generator, use it (but don't
+    # use UuidCreate here because its UUIDs don't conform to RFC 4122).
+    if _uuid_generate_time and node is clock_seq is None:
+        _uuid_generate_time(_buffer)
+        return UUID(bytes=_buffer.raw)
+
+    global _last_timestamp
+    import time
+    nanoseconds = int(time.time() * 1e9)
+    # 0x01b21dd213814000 is the number of 100-ns intervals between the
+    # UUID epoch 1582-10-15 00:00:00 and the Unix epoch 1970-01-01 00:00:00.
+    timestamp = int(nanoseconds/100) + 0x01b21dd213814000L
+    if timestamp <= _last_timestamp:
+        timestamp = _last_timestamp + 1
+    _last_timestamp = timestamp
+    if clock_seq is None:
+        import random
+        clock_seq = random.randrange(1<<14L) # instead of stable storage
+    time_low = timestamp & 0xffffffffL
+    time_mid = (timestamp >> 32L) & 0xffffL
+    time_hi_version = (timestamp >> 48L) & 0x0fffL
+    clock_seq_low = clock_seq & 0xffL
+    clock_seq_hi_variant = (clock_seq >> 8L) & 0x3fL
+    if node is None:
+        node = getnode()
+    return UUID(fields=(time_low, time_mid, time_hi_version,
+                        clock_seq_hi_variant, clock_seq_low, node), version=1)
+
+def uuid3(namespace, name):
+    """Generate a UUID from the MD5 hash of a namespace UUID and a name."""
+    import md5
+    hash = md5.md5(namespace.bytes + name).digest()
+    return UUID(bytes=hash[:16], version=3)
+
+def uuid4():
+    """Generate a random UUID."""
+
+    # When the system provides a version-4 UUID generator, use it.
+    if _uuid_generate_random:
+        _uuid_generate_random(_buffer)
+        return UUID(bytes=_buffer.raw)
+
+    # Otherwise, get randomness from urandom or the 'random' module.
+    try:
+        import os
+        return UUID(bytes=os.urandom(16), version=4)
+    except:
+        import random
+        bytes = [chr(random.randrange(256)) for i in range(16)]
+        return UUID(bytes=bytes, version=4)
+
+def uuid5(namespace, name):
+    """Generate a UUID from the SHA-1 hash of a namespace UUID and a name."""
+    import sha
+    hash = sha.sha(namespace.bytes + name).digest()
+    return UUID(bytes=hash[:16], version=5)
+
+# The following standard UUIDs are for use with uuid3() or uuid5().
+
+NAMESPACE_DNS = UUID('6ba7b810-9dad-11d1-80b4-00c04fd430c8')
+NAMESPACE_URL = UUID('6ba7b811-9dad-11d1-80b4-00c04fd430c8')
+NAMESPACE_OID = UUID('6ba7b812-9dad-11d1-80b4-00c04fd430c8')
+NAMESPACE_X500 = UUID('6ba7b814-9dad-11d1-80b4-00c04fd430c8')
-- 
2.43.0