X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=ovsdb%2Fjsonrpc-server.c;h=0cc8bdf9fa717bc32a4b28c6fba43d1272f99392;hb=e0edde6fee279cdbbf3c179f5f50adaf0c7c7f1e;hp=e97a2c333978b6e301132707cbc00b52738e0aa9;hpb=c2bffba3ee2c8f67863d2714c8d11acaec39632f;p=sliver-openvswitch.git

diff --git a/ovsdb/jsonrpc-server.c b/ovsdb/jsonrpc-server.c
index e97a2c333..0cc8bdf9f 100644
--- a/ovsdb/jsonrpc-server.c
+++ b/ovsdb/jsonrpc-server.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009 Nicira Networks
+/* Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,197 +17,813 @@
 
 #include "jsonrpc-server.h"
 
+#include <assert.h>
 #include <errno.h>
 
+#include "bitmap.h"
+#include "column.h"
+#include "dynamic-string.h"
 #include "json.h"
 #include "jsonrpc.h"
+#include "ovsdb-error.h"
+#include "ovsdb-parser.h"
 #include "ovsdb.h"
+#include "reconnect.h"
+#include "row.h"
+#include "server.h"
 #include "stream.h"
-#include "svec.h"
+#include "table.h"
 #include "timeval.h"
+#include "transaction.h"
 #include "trigger.h"
-
-#define THIS_MODULE VLM_ovsdb_jsonrpc_server
 #include "vlog.h"
 
-struct ovsdb_jsonrpc_trigger {
-    struct ovsdb_trigger trigger;
-    struct ovsdb_jsonrpc_session *session;
-    struct hmap_node hmap_node; /* Element in session's trigger table. */
-    struct json *id;
-};
+VLOG_DEFINE_THIS_MODULE(ovsdb_jsonrpc_server);
+
+struct ovsdb_jsonrpc_remote;
+struct ovsdb_jsonrpc_session;
+
+/* Message rate-limiting. */
+static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
 
+/* Sessions. */
+static struct ovsdb_jsonrpc_session *ovsdb_jsonrpc_session_create(
+    struct ovsdb_jsonrpc_remote *, struct jsonrpc_session *);
+static void ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *);
+static void ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *);
+static void ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *);
+static void ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *);
+static void ovsdb_jsonrpc_session_set_all_options(
+    struct ovsdb_jsonrpc_remote *, const struct ovsdb_jsonrpc_options *);
+static bool ovsdb_jsonrpc_session_get_status(
+    const struct ovsdb_jsonrpc_remote *,
+    struct ovsdb_jsonrpc_remote_status *);
+static void ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *);
+static void ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *);
+
+/* Triggers. */
+static void ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *,
+                                         struct json *id, struct json *params);
 static struct ovsdb_jsonrpc_trigger *ovsdb_jsonrpc_trigger_find(
     struct ovsdb_jsonrpc_session *, const struct json *id, size_t hash);
 static void ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *);
+static void ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *);
+static void ovsdb_jsonrpc_trigger_complete_done(
+    struct ovsdb_jsonrpc_session *);
 
-struct ovsdb_jsonrpc_session {
-    struct ovsdb_jsonrpc_server *server;
-    struct list node;           /* Element in server's sessions list. */
-    struct jsonrpc *rpc;
-    struct hmap triggers;
-    struct list completions;    /* Completed triggers. */
-};
-
-static void ovsdb_jsonrpc_session_open(struct ovsdb_jsonrpc_server *,
-                                       struct stream *);
-static void ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *);
-static void ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *,
-                                             struct jsonrpc_msg *);
-static void ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *,
-                                             struct jsonrpc_msg *);
+/* Monitors. */
+static struct json *ovsdb_jsonrpc_monitor_create(
+    struct ovsdb_jsonrpc_session *, struct json *params);
+static struct jsonrpc_msg *ovsdb_jsonrpc_monitor_cancel(
+    struct ovsdb_jsonrpc_session *,
+    struct json_array *params,
+    const struct json *request_id);
+static void ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *);
+
+/* JSON-RPC database server. */
 
 struct ovsdb_jsonrpc_server {
-    struct ovsdb *db;
-
-    struct list sessions;       /* List of "struct ovsdb_jsonrpc_session"s. */
+    struct ovsdb_server up;
     unsigned int n_sessions, max_sessions;
-    unsigned int max_triggers;
+    struct shash remotes;      /* Contains "struct ovsdb_jsonrpc_remote *"s. */
+};
 
-    struct pstream **listeners;
-    size_t n_listeners, allocated_listeners;
+/* A configured remote.  This is either a passive stream listener plus a list
+ * of the currently connected sessions, or a list of exactly one active
+ * session. */
+struct ovsdb_jsonrpc_remote {
+    struct ovsdb_jsonrpc_server *server;
+    struct pstream *listener;   /* Listener, if passive. */
+    struct list sessions;       /* List of "struct ovsdb_jsonrpc_session"s. */
 };
 
-static void ovsdb_jsonrpc_server_listen(struct ovsdb_jsonrpc_server *,
-                                        struct pstream *);
+static struct ovsdb_jsonrpc_remote *ovsdb_jsonrpc_server_add_remote(
+    struct ovsdb_jsonrpc_server *, const char *name,
+    const struct ovsdb_jsonrpc_options *options
+);
+static void ovsdb_jsonrpc_server_del_remote(struct shash_node *);
 
-int
-ovsdb_jsonrpc_server_create(struct ovsdb *db, const struct svec *active,
-                            const struct svec *passive,
-                            struct ovsdb_jsonrpc_server **serverp)
+struct ovsdb_jsonrpc_server *
+ovsdb_jsonrpc_server_create(struct ovsdb *db)
 {
-    struct ovsdb_jsonrpc_server *server;
-    const char *name;
-    int retval = 0;
-    size_t i;
-
-    server = xzalloc(sizeof *server);
-    server->db = db;
+    struct ovsdb_jsonrpc_server *server = xzalloc(sizeof *server);
+    ovsdb_server_init(&server->up, db);
     server->max_sessions = 64;
-    server->max_triggers = 64;
-    list_init(&server->sessions);
+    shash_init(&server->remotes);
+    return server;
+}
 
-    SVEC_FOR_EACH (i, name, active) {
-        struct stream *stream;
-        int error;
+void
+ovsdb_jsonrpc_server_destroy(struct ovsdb_jsonrpc_server *svr)
+{
+    struct shash_node *node, *next;
 
-        error = stream_open(name, &stream);
-        if (!error) {
-            ovsdb_jsonrpc_session_open(server, stream);
-        } else {
-            ovs_error(error, "%s: connection failed", name);
-            retval = error;
-        }
+    SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
+        ovsdb_jsonrpc_server_del_remote(node);
     }
+    shash_destroy(&svr->remotes);
+    ovsdb_server_destroy(&svr->up);
+    free(svr);
+}
 
-    SVEC_FOR_EACH (i, name, passive) {
-        struct pstream *pstream;
-        int error;
+struct ovsdb_jsonrpc_options *
+ovsdb_jsonrpc_default_options(const char *target)
+{
+    struct ovsdb_jsonrpc_options *options = xzalloc(sizeof *options);
+    options->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
+    options->probe_interval = (stream_or_pstream_needs_probes(target)
+                               ? RECONNECT_DEFAULT_PROBE_INTERVAL
+                               : 0);
+    return options;
+}
 
-        error = pstream_open(name, &pstream);
-        if (!error) {
-            ovsdb_jsonrpc_server_listen(server, pstream);
-        } else {
-            ovs_error(error, "failed to listen on %s", name);
-            retval = error;
+/* Sets 'svr''s current set of remotes to the names in 'new_remotes', with
+ * options in the struct ovsdb_jsonrpc_options supplied as the data values.
+ *
+ * A remote is an active or passive stream connection method, e.g. "pssl:" or
+ * "tcp:1.2.3.4". */
+void
+ovsdb_jsonrpc_server_set_remotes(struct ovsdb_jsonrpc_server *svr,
+                                 const struct shash *new_remotes)
+{
+    struct shash_node *node, *next;
+
+    SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
+        if (!shash_find(new_remotes, node->name)) {
+            VLOG_INFO("%s: remote deconfigured", node->name);
+            ovsdb_jsonrpc_server_del_remote(node);
+        }
+    }
+    SHASH_FOR_EACH (node, new_remotes) {
+        const struct ovsdb_jsonrpc_options *options = node->data;
+        struct ovsdb_jsonrpc_remote *remote;
+
+        remote = shash_find_data(&svr->remotes, node->name);
+        if (!remote) {
+            remote = ovsdb_jsonrpc_server_add_remote(svr, node->name, options);
+            if (!remote) {
+                continue;
+            }
         }
+
+        ovsdb_jsonrpc_session_set_all_options(remote, options);
+    }
+}
+
+static struct ovsdb_jsonrpc_remote *
+ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *svr,
+                                const char *name,
+                                const struct ovsdb_jsonrpc_options *options)
+{
+    struct ovsdb_jsonrpc_remote *remote;
+    struct pstream *listener;
+    int error;
+
+    error = jsonrpc_pstream_open(name, &listener, options->dscp);
+    if (error && error != EAFNOSUPPORT) {
+        VLOG_ERR_RL(&rl, "%s: listen failed: %s", name, strerror(error));
+        return NULL;
+    }
+
+    remote = xmalloc(sizeof *remote);
+    remote->server = svr;
+    remote->listener = listener;
+    list_init(&remote->sessions);
+    shash_add(&svr->remotes, name, remote);
+
+    if (!listener) {
+        ovsdb_jsonrpc_session_create(remote, jsonrpc_session_open(name));
     }
+    return remote;
+}
+
+static void
+ovsdb_jsonrpc_server_del_remote(struct shash_node *node)
+{
+    struct ovsdb_jsonrpc_remote *remote = node->data;
+
+    ovsdb_jsonrpc_session_close_all(remote);
+    pstream_close(remote->listener);
+    shash_delete(&remote->server->remotes, node);
+    free(remote);
+}
+
+/* Stores status information for the remote named 'target', which should have
+ * been configured on 'svr' with a call to ovsdb_jsonrpc_server_set_remotes(),
+ * into '*status'.  On success returns true, on failure (if 'svr' doesn't have
+ * a remote named 'target' or if that remote is an inbound remote that has no
+ * active connections) returns false.  On failure, 'status' will be zeroed.
+ */
+bool
+ovsdb_jsonrpc_server_get_remote_status(
+    const struct ovsdb_jsonrpc_server *svr, const char *target,
+    struct ovsdb_jsonrpc_remote_status *status)
+{
+    const struct ovsdb_jsonrpc_remote *remote;
+
+    memset(status, 0, sizeof *status);
+
+    remote = shash_find_data(&svr->remotes, target);
+    return remote && ovsdb_jsonrpc_session_get_status(remote, status);
+}
 
-    *serverp = server;
-    return retval;
+void
+ovsdb_jsonrpc_server_free_remote_status(
+    struct ovsdb_jsonrpc_remote_status *status)
+{
+    free(status->locks_held);
+    free(status->locks_waiting);
+    free(status->locks_lost);
+}
+
+/* Forces all of the JSON-RPC sessions managed by 'svr' to disconnect and
+ * reconnect. */
+void
+ovsdb_jsonrpc_server_reconnect(struct ovsdb_jsonrpc_server *svr)
+{
+    struct shash_node *node;
+
+    SHASH_FOR_EACH (node, &svr->remotes) {
+        struct ovsdb_jsonrpc_remote *remote = node->data;
+
+        ovsdb_jsonrpc_session_reconnect_all(remote);
+    }
 }
 
 void
 ovsdb_jsonrpc_server_run(struct ovsdb_jsonrpc_server *svr)
 {
-    struct ovsdb_jsonrpc_session *s, *next;
-    size_t i;
+    struct shash_node *node;
+
+    SHASH_FOR_EACH (node, &svr->remotes) {
+        struct ovsdb_jsonrpc_remote *remote = node->data;
 
-    /* Accept new connections. */
-    for (i = 0; i < svr->n_listeners && svr->n_sessions < svr->max_sessions;) {
-        struct pstream *listener = svr->listeners[i];
-        struct stream *stream;
-        int error;
+        if (remote->listener && svr->n_sessions < svr->max_sessions) {
+            struct stream *stream;
+            int error;
 
-        error = pstream_accept(listener, &stream);
-        if (!error) {
-            ovsdb_jsonrpc_session_open(svr, stream);
-        } else if (error == EAGAIN) {
-            i++;
-        } else if (error) {
-            VLOG_WARN("%s: accept failed: %s",
-                      pstream_get_name(listener), strerror(error));
-            pstream_close(listener);
-            svr->listeners[i] = svr->listeners[--svr->n_listeners];
+            error = pstream_accept(remote->listener, &stream);
+            if (!error) {
+                struct jsonrpc_session *js;
+                js = jsonrpc_session_open_unreliably(jsonrpc_open(stream));
+                ovsdb_jsonrpc_session_create(remote, js);
+            } else if (error != EAGAIN) {
+                VLOG_WARN_RL(&rl, "%s: accept failed: %s",
+                             pstream_get_name(remote->listener),
+                             strerror(error));
+            }
         }
+
+        ovsdb_jsonrpc_session_run_all(remote);
     }
+}
 
-    /* Handle each session. */
-    LIST_FOR_EACH_SAFE (s, next, struct ovsdb_jsonrpc_session, node,
-                        &svr->sessions) {
-        struct jsonrpc_msg *msg;
-        int error;
+void
+ovsdb_jsonrpc_server_wait(struct ovsdb_jsonrpc_server *svr)
+{
+    struct shash_node *node;
 
-        jsonrpc_run(s->rpc);
+    SHASH_FOR_EACH (node, &svr->remotes) {
+        struct ovsdb_jsonrpc_remote *remote = node->data;
 
-        while (!list_is_empty(&s->completions)) {
-            struct ovsdb_jsonrpc_trigger *t
-                = CONTAINER_OF(s->completions.next,
-                               struct ovsdb_jsonrpc_trigger, trigger.node);
-            ovsdb_jsonrpc_trigger_complete(t);
+        if (remote->listener && svr->n_sessions < svr->max_sessions) {
+            pstream_wait(remote->listener);
         }
 
-        if (!jsonrpc_get_backlog(s->rpc) && !jsonrpc_recv(s->rpc, &msg)) {
+        ovsdb_jsonrpc_session_wait_all(remote);
+    }
+}
+
+/* JSON-RPC database server session. */
+
+struct ovsdb_jsonrpc_session {
+    struct list node;           /* Element in remote's sessions list. */
+    struct ovsdb_session up;
+    struct ovsdb_jsonrpc_remote *remote;
+
+    /* Triggers. */
+    struct hmap triggers;       /* Hmap of "struct ovsdb_jsonrpc_trigger"s. */
+
+    /* Monitors. */
+    struct hmap monitors;       /* Hmap of "struct ovsdb_jsonrpc_monitor"s. */
+
+    /* Network connectivity. */
+    struct jsonrpc_session *js;  /* JSON-RPC session. */
+    unsigned int js_seqno;       /* Last jsonrpc_session_get_seqno() value. */
+};
+
+static void ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *);
+static int ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *);
+static void ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *);
+static void ovsdb_jsonrpc_session_set_options(
+    struct ovsdb_jsonrpc_session *, const struct ovsdb_jsonrpc_options *);
+static void ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *,
+                                             struct jsonrpc_msg *);
+static void ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *,
+                                             struct jsonrpc_msg *);
+
+static struct ovsdb_jsonrpc_session *
+ovsdb_jsonrpc_session_create(struct ovsdb_jsonrpc_remote *remote,
+                             struct jsonrpc_session *js)
+{
+    struct ovsdb_jsonrpc_session *s;
+
+    s = xzalloc(sizeof *s);
+    ovsdb_session_init(&s->up, remote->server->up.db);
+    s->remote = remote;
+    list_push_back(&remote->sessions, &s->node);
+    hmap_init(&s->triggers);
+    hmap_init(&s->monitors);
+    s->js = js;
+    s->js_seqno = jsonrpc_session_get_seqno(js);
+
+    remote->server->n_sessions++;
+
+    return s;
+}
+
+static void
+ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *s)
+{
+    ovsdb_jsonrpc_monitor_remove_all(s);
+    ovsdb_jsonrpc_session_unlock_all(s);
+    jsonrpc_session_close(s->js);
+    list_remove(&s->node);
+    ovsdb_session_destroy(&s->up);
+    s->remote->server->n_sessions--;
+    ovsdb_session_destroy(&s->up);
+    free(s);
+}
+
+static int
+ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
+{
+    jsonrpc_session_run(s->js);
+    if (s->js_seqno != jsonrpc_session_get_seqno(s->js)) {
+        s->js_seqno = jsonrpc_session_get_seqno(s->js);
+        ovsdb_jsonrpc_trigger_complete_all(s);
+        ovsdb_jsonrpc_monitor_remove_all(s);
+        ovsdb_jsonrpc_session_unlock_all(s);
+    }
+
+    ovsdb_jsonrpc_trigger_complete_done(s);
+
+    if (!jsonrpc_session_get_backlog(s->js)) {
+        struct jsonrpc_msg *msg = jsonrpc_session_recv(s->js);
+        if (msg) {
             if (msg->type == JSONRPC_REQUEST) {
                 ovsdb_jsonrpc_session_got_request(s, msg);
             } else if (msg->type == JSONRPC_NOTIFY) {
                 ovsdb_jsonrpc_session_got_notify(s, msg);
             } else {
                 VLOG_WARN("%s: received unexpected %s message",
-                          jsonrpc_get_name(s->rpc),
+                          jsonrpc_session_get_name(s->js),
                           jsonrpc_msg_type_to_string(msg->type));
-                jsonrpc_error(s->rpc, EPROTO);
+                jsonrpc_session_force_reconnect(s->js);
                 jsonrpc_msg_destroy(msg);
             }
         }
+    }
+    return jsonrpc_session_is_alive(s->js) ? 0 : ETIMEDOUT;
+}
+
+static void
+ovsdb_jsonrpc_session_set_options(struct ovsdb_jsonrpc_session *session,
+                                  const struct ovsdb_jsonrpc_options *options)
+{
+    jsonrpc_session_set_max_backoff(session->js, options->max_backoff);
+    jsonrpc_session_set_probe_interval(session->js, options->probe_interval);
+    jsonrpc_session_set_dscp(session->js, options->dscp);
+}
+
+static void
+ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *remote)
+{
+    struct ovsdb_jsonrpc_session *s, *next;
 
-        error = jsonrpc_get_status(s->rpc);
+    LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
+        int error = ovsdb_jsonrpc_session_run(s);
         if (error) {
             ovsdb_jsonrpc_session_close(s);
         }
     }
 }
 
-void
-ovsdb_jsonrpc_server_wait(struct ovsdb_jsonrpc_server *svr)
+static void
+ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *s)
+{
+    jsonrpc_session_wait(s->js);
+    if (!jsonrpc_session_get_backlog(s->js)) {
+        jsonrpc_session_recv_wait(s->js);
+    }
+}
+
+static void
+ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *remote)
 {
     struct ovsdb_jsonrpc_session *s;
 
-    if (svr->n_sessions < svr->max_sessions) {
-        size_t i;
+    LIST_FOR_EACH (s, node, &remote->sessions) {
+        ovsdb_jsonrpc_session_wait(s);
+    }
+}
+
+static void
+ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *remote)
+{
+    struct ovsdb_jsonrpc_session *s, *next;
+
+    LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
+        ovsdb_jsonrpc_session_close(s);
+    }
+}
+
+/* Forces all of the JSON-RPC sessions managed by 'remote' to disconnect and
+ * reconnect. */
+static void
+ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *remote)
+{
+    struct ovsdb_jsonrpc_session *s, *next;
 
-        for (i = 0; i < svr->n_listeners; i++) {
-            pstream_wait(svr->listeners[i]);
+    LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
+        jsonrpc_session_force_reconnect(s->js);
+        if (!jsonrpc_session_is_alive(s->js)) {
+            ovsdb_jsonrpc_session_close(s);
         }
     }
+}
+
+/* Sets the options for all of the JSON-RPC sessions managed by 'remote' to
+ * 'options'. */
+static void
+ovsdb_jsonrpc_session_set_all_options(
+    struct ovsdb_jsonrpc_remote *remote,
+    const struct ovsdb_jsonrpc_options *options)
+{
+    struct ovsdb_jsonrpc_session *s;
+
+    LIST_FOR_EACH (s, node, &remote->sessions) {
+        ovsdb_jsonrpc_session_set_options(s, options);
+    }
+}
+
+static bool
+ovsdb_jsonrpc_session_get_status(const struct ovsdb_jsonrpc_remote *remote,
+                                 struct ovsdb_jsonrpc_remote_status *status)
+{
+    const struct ovsdb_jsonrpc_session *s;
+    const struct jsonrpc_session *js;
+    struct ovsdb_lock_waiter *waiter;
+    struct reconnect_stats rstats;
+    struct ds locks_held, locks_waiting, locks_lost;
+
+    if (list_is_empty(&remote->sessions)) {
+        return false;
+    }
+    s = CONTAINER_OF(remote->sessions.next, struct ovsdb_jsonrpc_session, node);
+    js = s->js;
+
+    status->is_connected = jsonrpc_session_is_connected(js);
+    status->last_error = jsonrpc_session_get_status(js);
 
-    LIST_FOR_EACH (s, struct ovsdb_jsonrpc_session, node, &svr->sessions) {
-        jsonrpc_wait(s->rpc);
-        if (!jsonrpc_get_backlog(s->rpc)) {
-            jsonrpc_recv_wait(s->rpc);
+    jsonrpc_session_get_reconnect_stats(js, &rstats);
+    status->state = rstats.state;
+    status->sec_since_connect = rstats.msec_since_connect == UINT_MAX
+        ? UINT_MAX : rstats.msec_since_connect / 1000;
+    status->sec_since_disconnect = rstats.msec_since_disconnect == UINT_MAX
+        ? UINT_MAX : rstats.msec_since_disconnect / 1000;
+
+    ds_init(&locks_held);
+    ds_init(&locks_waiting);
+    ds_init(&locks_lost);
+    HMAP_FOR_EACH (waiter, session_node, &s->up.waiters) {
+        struct ds *string;
+
+        string = (ovsdb_lock_waiter_is_owner(waiter) ? &locks_held
+                  : waiter->mode == OVSDB_LOCK_WAIT ? &locks_waiting
+                  : &locks_lost);
+        if (string->length) {
+            ds_put_char(string, ' ');
         }
+        ds_put_cstr(string, waiter->lock_name);
+    }
+    status->locks_held = ds_steal_cstr(&locks_held);
+    status->locks_waiting = ds_steal_cstr(&locks_waiting);
+    status->locks_lost = ds_steal_cstr(&locks_lost);
+
+    status->n_connections = list_size(&remote->sessions);
+
+    return true;
+}
+
+static const char *
+get_db_name(const struct ovsdb_jsonrpc_session *s)
+{
+    return s->remote->server->up.db->schema->name;
+}
+
+static struct jsonrpc_msg *
+ovsdb_jsonrpc_check_db_name(const struct ovsdb_jsonrpc_session *s,
+                            const struct jsonrpc_msg *request)
+{
+    struct json_array *params;
+    const char *want_db_name;
+    const char *have_db_name;
+    struct ovsdb_error *error;
+    struct jsonrpc_msg *reply;
+
+    params = json_array(request->params);
+    if (!params->n || params->elems[0]->type != JSON_STRING) {
+        error = ovsdb_syntax_error(
+            request->params, NULL,
+            "%s request params must begin with <db-name>", request->method);
+        goto error;
+    }
+
+    want_db_name = params->elems[0]->u.string;
+    have_db_name = get_db_name(s);
+    if (strcmp(want_db_name, have_db_name)) {
+        error = ovsdb_syntax_error(
+            request->params, "unknown database",
+            "%s request specifies unknown database %s",
+            request->method, want_db_name);
+        goto error;
+    }
+
+    return NULL;
+
+error:
+    reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
+    ovsdb_error_destroy(error);
+    return reply;
+}
+
+static struct ovsdb_error *
+ovsdb_jsonrpc_session_parse_lock_name(const struct jsonrpc_msg *request,
+                                      const char **lock_namep)
+{
+    const struct json_array *params;
+
+    params = json_array(request->params);
+    if (params->n != 1 || params->elems[0]->type != JSON_STRING ||
+        !ovsdb_parser_is_id(json_string(params->elems[0]))) {
+        *lock_namep = NULL;
+        return ovsdb_syntax_error(request->params, NULL,
+                                  "%s request params must be <id>",
+                                  request->method);
     }
+
+    *lock_namep = json_string(params->elems[0]);
+    return NULL;
 }
 
 static void
-ovsdb_jsonrpc_server_listen(struct ovsdb_jsonrpc_server *svr,
-                            struct pstream *pstream)
+ovsdb_jsonrpc_session_notify(struct ovsdb_session *session,
+                             const char *lock_name,
+                             const char *method)
 {
-    if (svr->n_listeners >= svr->allocated_listeners) {
-        svr->listeners = x2nrealloc(svr->listeners, &svr->allocated_listeners,
-                                    sizeof *svr->listeners);
+    struct ovsdb_jsonrpc_session *s;
+    struct json *params;
+
+    s = CONTAINER_OF(session, struct ovsdb_jsonrpc_session, up);
+    params = json_array_create_1(json_string_create(lock_name));
+    jsonrpc_session_send(s->js, jsonrpc_create_notify(method, params));
+}
+
+static struct jsonrpc_msg *
+ovsdb_jsonrpc_session_lock(struct ovsdb_jsonrpc_session *s,
+                           struct jsonrpc_msg *request,
+                           enum ovsdb_lock_mode mode)
+{
+    struct ovsdb_lock_waiter *waiter;
+    struct jsonrpc_msg *reply;
+    struct ovsdb_error *error;
+    struct ovsdb_session *victim;
+    const char *lock_name;
+    struct json *result;
+
+    error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
+    if (error) {
+        goto error;
+    }
+
+    /* Report error if this session has issued a "lock" or "steal" without a
+     * matching "unlock" for this lock. */
+    waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
+    if (waiter) {
+        error = ovsdb_syntax_error(
+            request->params, NULL,
+            "must issue \"unlock\" before new \"%s\"", request->method);
+        goto error;
+    }
+
+    /* Get the lock, add us as a waiter. */
+    waiter = ovsdb_server_lock(&s->remote->server->up, &s->up, lock_name, mode,
+                               &victim);
+    if (victim) {
+        ovsdb_jsonrpc_session_notify(victim, lock_name, "stolen");
+    }
+
+    result = json_object_create();
+    json_object_put(result, "locked",
+                    json_boolean_create(ovsdb_lock_waiter_is_owner(waiter)));
+
+    return jsonrpc_create_reply(result, request->id);
+
+error:
+    reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
+    ovsdb_error_destroy(error);
+    return reply;
+}
+
+static void
+ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *s)
+{
+    struct ovsdb_lock_waiter *waiter, *next;
+
+    HMAP_FOR_EACH_SAFE (waiter, next, session_node, &s->up.waiters) {
+        ovsdb_jsonrpc_session_unlock__(waiter);
+    }
+}
+
+static void
+ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *waiter)
+{
+    struct ovsdb_lock *lock = waiter->lock;
+
+    if (lock) {
+        struct ovsdb_session *new_owner = ovsdb_lock_waiter_remove(waiter);
+        if (new_owner) {
+            ovsdb_jsonrpc_session_notify(new_owner, lock->name, "locked");
+        } else {
+            /* ovsdb_server_lock() might have freed 'lock'. */
+        }
+    }
+
+    ovsdb_lock_waiter_destroy(waiter);
+}
+
+static struct jsonrpc_msg *
+ovsdb_jsonrpc_session_unlock(struct ovsdb_jsonrpc_session *s,
+                             struct jsonrpc_msg *request)
+{
+    struct ovsdb_lock_waiter *waiter;
+    struct jsonrpc_msg *reply;
+    struct ovsdb_error *error;
+    const char *lock_name;
+
+    error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
+    if (error) {
+        goto error;
+    }
+
+    /* Report error if this session has not issued a "lock" or "steal" for this
+     * lock. */
+    waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
+    if (!waiter) {
+        error = ovsdb_syntax_error(
+            request->params, NULL, "\"unlock\" without \"lock\" or \"steal\"");
+        goto error;
+    }
+
+    ovsdb_jsonrpc_session_unlock__(waiter);
+
+    return jsonrpc_create_reply(json_object_create(), request->id);
+
+error:
+    reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
+    ovsdb_error_destroy(error);
+    return reply;
+}
+
+static struct jsonrpc_msg *
+execute_transaction(struct ovsdb_jsonrpc_session *s,
+                    struct jsonrpc_msg *request)
+{
+    ovsdb_jsonrpc_trigger_create(s, request->id, request->params);
+    request->id = NULL;
+    request->params = NULL;
+    jsonrpc_msg_destroy(request);
+    return NULL;
+}
+
+static void
+ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *s,
+                                  struct jsonrpc_msg *request)
+{
+    struct jsonrpc_msg *reply;
+
+    if (!strcmp(request->method, "transact")) {
+        reply = ovsdb_jsonrpc_check_db_name(s, request);
+        if (!reply) {
+            reply = execute_transaction(s, request);
+        }
+    } else if (!strcmp(request->method, "monitor")) {
+        reply = ovsdb_jsonrpc_check_db_name(s, request);
+        if (!reply) {
+            reply = jsonrpc_create_reply(
+                ovsdb_jsonrpc_monitor_create(s, request->params), request->id);
+        }
+    } else if (!strcmp(request->method, "monitor_cancel")) {
+        reply = ovsdb_jsonrpc_monitor_cancel(s, json_array(request->params),
+                                             request->id);
+    } else if (!strcmp(request->method, "get_schema")) {
+        reply = ovsdb_jsonrpc_check_db_name(s, request);
+        if (!reply) {
+            reply = jsonrpc_create_reply(
+                ovsdb_schema_to_json(s->remote->server->up.db->schema),
+                request->id);
+        }
+    } else if (!strcmp(request->method, "list_dbs")) {
+        reply = jsonrpc_create_reply(
+            json_array_create_1(json_string_create(get_db_name(s))),
+            request->id);
+    } else if (!strcmp(request->method, "lock")) {
+        reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_WAIT);
+    } else if (!strcmp(request->method, "steal")) {
+        reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_STEAL);
+    } else if (!strcmp(request->method, "unlock")) {
+        reply = ovsdb_jsonrpc_session_unlock(s, request);
+    } else if (!strcmp(request->method, "echo")) {
+        reply = jsonrpc_create_reply(json_clone(request->params), request->id);
+    } else {
+        reply = jsonrpc_create_error(json_string_create("unknown method"),
+                                     request->id);
+    }
+
+    if (reply) {
+        jsonrpc_msg_destroy(request);
+        jsonrpc_session_send(s->js, reply);
+    }
+}
+
+static void
+execute_cancel(struct ovsdb_jsonrpc_session *s, struct jsonrpc_msg *request)
+{
+    if (json_array(request->params)->n == 1) {
+        struct ovsdb_jsonrpc_trigger *t;
+        struct json *id;
+
+        id = request->params->u.array.elems[0];
+        t = ovsdb_jsonrpc_trigger_find(s, id, json_hash(id, 0));
+        if (t) {
+            ovsdb_jsonrpc_trigger_complete(t);
+        }
+    }
+}
+
+static void
+ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *s,
+                                 struct jsonrpc_msg *request)
+{
+    if (!strcmp(request->method, "cancel")) {
+        execute_cancel(s, request);
+    }
+    jsonrpc_msg_destroy(request);
+}
+
+/* JSON-RPC database server triggers.
+ *
+ * (Every transaction is treated as a trigger even if it doesn't actually have
+ * any "wait" operations.) */
+
+struct ovsdb_jsonrpc_trigger {
+    struct ovsdb_trigger trigger;
+    struct hmap_node hmap_node; /* In session's "triggers" hmap. */
+    struct json *id;
+};
+
+static void
+ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *s,
+                             struct json *id, struct json *params)
+{
+    struct ovsdb_jsonrpc_trigger *t;
+    size_t hash;
+
+    /* Check for duplicate ID. */
+    hash = json_hash(id, 0);
+    t = ovsdb_jsonrpc_trigger_find(s, id, hash);
+    if (t) {
+        struct jsonrpc_msg *msg;
+
+        msg = jsonrpc_create_error(json_string_create("duplicate request ID"),
+                                   id);
+        jsonrpc_session_send(s->js, msg);
+        json_destroy(id);
+        json_destroy(params);
+        return;
+    }
+
+    /* Insert into trigger table. */
+    t = xmalloc(sizeof *t);
+    ovsdb_trigger_init(&s->up, &t->trigger, params, time_msec());
+    t->id = id;
+    hmap_insert(&s->triggers, &t->hmap_node, hash);
+
+    /* Complete early if possible. */
+    if (ovsdb_trigger_is_complete(&t->trigger)) {
+        ovsdb_jsonrpc_trigger_complete(t);
     }
-    svr->listeners[svr->n_listeners++] = pstream;
 }
 
 static struct ovsdb_jsonrpc_trigger *
@@ -216,8 +832,7 @@ ovsdb_jsonrpc_trigger_find(struct ovsdb_jsonrpc_session *s,
 {
     struct ovsdb_jsonrpc_trigger *t;
 
-    HMAP_FOR_EACH_WITH_HASH (t, struct ovsdb_jsonrpc_trigger, hmap_node, hash,
-                             &s->triggers) {
+    HMAP_FOR_EACH_WITH_HASH (t, hmap_node, hash, &s->triggers) {
         if (json_equal(t->id, id)) {
             return t;
         }
@@ -229,9 +844,11 @@ ovsdb_jsonrpc_trigger_find(struct ovsdb_jsonrpc_session *s,
 static void
 ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *t)
 {
-    struct ovsdb_jsonrpc_session *s = t->session;
+    struct ovsdb_jsonrpc_session *s;
 
-    if (!jsonrpc_get_status(s->rpc)) {
+    s = CONTAINER_OF(t->trigger.session, struct ovsdb_jsonrpc_session, up);
+
+    if (jsonrpc_session_is_connected(s->js)) {
         struct jsonrpc_msg *reply;
         struct json *result;
 
@@ -242,7 +859,7 @@ ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *t)
             reply = jsonrpc_create_error(json_string_create("canceled"),
                                          t->id);
         }
-        jsonrpc_send(s->rpc, reply);
+        jsonrpc_session_send(s->js, reply);
     }
 
     json_destroy(t->id);
@@ -252,112 +869,547 @@ ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *t)
 }
 
 static void
-ovsdb_jsonrpc_session_open(struct ovsdb_jsonrpc_server *svr,
-                           struct stream *stream)
+ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *s)
 {
-    struct ovsdb_jsonrpc_session *s;
+    struct ovsdb_jsonrpc_trigger *t, *next;
+    HMAP_FOR_EACH_SAFE (t, next, hmap_node, &s->triggers) {
+        ovsdb_jsonrpc_trigger_complete(t);
+    }
+}
 
-    s = xzalloc(sizeof *s);
-    s->server = svr;
-    list_push_back(&svr->sessions, &s->node);
-    s->rpc = jsonrpc_open(stream);
-    hmap_init(&s->triggers);
-    list_init(&s->completions);
-    svr->n_sessions++;
+static void
+ovsdb_jsonrpc_trigger_complete_done(struct ovsdb_jsonrpc_session *s)
+{
+    while (!list_is_empty(&s->up.completions)) {
+        struct ovsdb_jsonrpc_trigger *t
+            = CONTAINER_OF(s->up.completions.next,
+                           struct ovsdb_jsonrpc_trigger, trigger.node);
+        ovsdb_jsonrpc_trigger_complete(t);
+    }
+}
+
+/* JSON-RPC database table monitors. */
+
+enum ovsdb_jsonrpc_monitor_selection {
+    OJMS_INITIAL = 1 << 0,      /* All rows when monitor is created. */
+    OJMS_INSERT = 1 << 1,       /* New rows. */
+    OJMS_DELETE = 1 << 2,       /* Deleted rows. */
+    OJMS_MODIFY = 1 << 3        /* Modified rows. */
+};
+
+/* A particular column being monitored. */
+struct ovsdb_jsonrpc_monitor_column {
+    const struct ovsdb_column *column;
+    enum ovsdb_jsonrpc_monitor_selection select;
+};
+
+/* A particular table being monitored. */
+struct ovsdb_jsonrpc_monitor_table {
+    const struct ovsdb_table *table;
+
+    /* This is the union (bitwise-OR) of the 'select' values in all of the
+     * members of 'columns' below. */
+    enum ovsdb_jsonrpc_monitor_selection select;
+
+    /* Columns being monitored. */
+    struct ovsdb_jsonrpc_monitor_column *columns;
+    size_t n_columns;
+};
+
+/* A collection of tables being monitored. */
+struct ovsdb_jsonrpc_monitor {
+    struct ovsdb_replica replica;
+    struct ovsdb_jsonrpc_session *session;
+    struct hmap_node node;      /* In ovsdb_jsonrpc_session's "monitors". */
+
+    struct json *monitor_id;
+    struct shash tables;     /* Holds "struct ovsdb_jsonrpc_monitor_table"s. */
+};
+
+static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class;
+
+struct ovsdb_jsonrpc_monitor *ovsdb_jsonrpc_monitor_find(
+    struct ovsdb_jsonrpc_session *, const struct json *monitor_id);
+static void ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *);
+static struct json *ovsdb_jsonrpc_monitor_get_initial(
+    const struct ovsdb_jsonrpc_monitor *);
+
+static bool
+parse_bool(struct ovsdb_parser *parser, const char *name, bool default_value)
+{
+    const struct json *json;
+
+    json = ovsdb_parser_member(parser, name, OP_BOOLEAN | OP_OPTIONAL);
+    return json ? json_boolean(json) : default_value;
+}
+
+struct ovsdb_jsonrpc_monitor *
+ovsdb_jsonrpc_monitor_find(struct ovsdb_jsonrpc_session *s,
+                           const struct json *monitor_id)
+{
+    struct ovsdb_jsonrpc_monitor *m;
+
+    HMAP_FOR_EACH_WITH_HASH (m, node, json_hash(monitor_id, 0), &s->monitors) {
+        if (json_equal(m->monitor_id, monitor_id)) {
+            return m;
+        }
+    }
+
+    return NULL;
 }
 
 static void
-ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *s)
+ovsdb_jsonrpc_add_monitor_column(struct ovsdb_jsonrpc_monitor_table *mt,
+                                 const struct ovsdb_column *column,
+                                 enum ovsdb_jsonrpc_monitor_selection select,
+                                 size_t *allocated_columns)
 {
-    struct ovsdb_jsonrpc_trigger *t, *next;
+    struct ovsdb_jsonrpc_monitor_column *c;
 
-    jsonrpc_error(s->rpc, EOF);
-    HMAP_FOR_EACH_SAFE (t, next, struct ovsdb_jsonrpc_trigger, hmap_node,
-                        &s->triggers) {
-        ovsdb_jsonrpc_trigger_complete(t);
+    if (mt->n_columns >= *allocated_columns) {
+        mt->columns = x2nrealloc(mt->columns, allocated_columns,
+                                 sizeof *mt->columns);
     }
 
-    jsonrpc_close(s->rpc);
+    c = &mt->columns[mt->n_columns++];
+    c->column = column;
+    c->select = select;
+}
 
-    list_remove(&s->node);
-    s->server->n_sessions--;
+static int
+compare_ovsdb_jsonrpc_monitor_column(const void *a_, const void *b_)
+{
+    const struct ovsdb_jsonrpc_monitor_column *a = a_;
+    const struct ovsdb_jsonrpc_monitor_column *b = b_;
+
+    return a->column < b->column ? -1 : a->column > b->column;
 }
 
-static struct jsonrpc_msg *
-execute_transaction(struct ovsdb_jsonrpc_session *s,
-                    struct jsonrpc_msg *request)
+static struct ovsdb_error * WARN_UNUSED_RESULT
+ovsdb_jsonrpc_parse_monitor_request(struct ovsdb_jsonrpc_monitor_table *mt,
+                                    const struct json *monitor_request,
+                                    size_t *allocated_columns)
 {
-    struct ovsdb_jsonrpc_trigger *t;
-    size_t hash;
+    const struct ovsdb_table_schema *ts = mt->table->schema;
+    enum ovsdb_jsonrpc_monitor_selection select;
+    const struct json *columns, *select_json;
+    struct ovsdb_parser parser;
+    struct ovsdb_error *error;
 
-    /* Check for duplicate ID. */
-    hash = json_hash(request->id, 0);
-    t = ovsdb_jsonrpc_trigger_find(s, request->id, hash);
-    if (t) {
-        return jsonrpc_create_error(
-            json_string_create("duplicate request ID"), request->id);
+    ovsdb_parser_init(&parser, monitor_request, "table %s", ts->name);
+    columns = ovsdb_parser_member(&parser, "columns", OP_ARRAY | OP_OPTIONAL);
+    select_json = ovsdb_parser_member(&parser, "select",
+                                      OP_OBJECT | OP_OPTIONAL);
+    error = ovsdb_parser_finish(&parser);
+    if (error) {
+        return error;
     }
 
-    /* Insert into trigger table. */
-    t = xmalloc(sizeof *t);
-    ovsdb_trigger_init(s->server->db,
-                       &t->trigger, request->params, &s->completions,
-                       time_msec());
-    t->session = s;
-    t->id = request->id;
-    hmap_insert(&s->triggers, &t->hmap_node, hash);
+    if (select_json) {
+        select = 0;
+        ovsdb_parser_init(&parser, select_json, "table %s select", ts->name);
+        if (parse_bool(&parser, "initial", true)) {
+            select |= OJMS_INITIAL;
+        }
+        if (parse_bool(&parser, "insert", true)) {
+            select |= OJMS_INSERT;
+        }
+        if (parse_bool(&parser, "delete", true)) {
+            select |= OJMS_DELETE;
+        }
+        if (parse_bool(&parser, "modify", true)) {
+            select |= OJMS_MODIFY;
+        }
+        error = ovsdb_parser_finish(&parser);
+        if (error) {
+            return error;
+        }
+    } else {
+        select = OJMS_INITIAL | OJMS_INSERT | OJMS_DELETE | OJMS_MODIFY;
+    }
+    mt->select |= select;
 
-    request->id = NULL;
-    request->params = NULL;
+    if (columns) {
+        size_t i;
 
-    /* Complete early if possible. */
-    if (ovsdb_trigger_is_complete(&t->trigger)) {
-        ovsdb_jsonrpc_trigger_complete(t);
+        if (columns->type != JSON_ARRAY) {
+            return ovsdb_syntax_error(columns, NULL,
+                                      "array of column names expected");
+        }
+
+        for (i = 0; i < columns->u.array.n; i++) {
+            const struct ovsdb_column *column;
+            const char *s;
+
+            if (columns->u.array.elems[i]->type != JSON_STRING) {
+                return ovsdb_syntax_error(columns, NULL,
+                                          "array of column names expected");
+            }
+
+            s = columns->u.array.elems[i]->u.string;
+            column = shash_find_data(&mt->table->schema->columns, s);
+            if (!column) {
+                return ovsdb_syntax_error(columns, NULL, "%s is not a valid "
+                                          "column name", s);
+            }
+            ovsdb_jsonrpc_add_monitor_column(mt, column, select,
+                                             allocated_columns);
+        }
+    } else {
+        struct shash_node *node;
+
+        SHASH_FOR_EACH (node, &ts->columns) {
+            const struct ovsdb_column *column = node->data;
+            if (column->index != OVSDB_COL_UUID) {
+                ovsdb_jsonrpc_add_monitor_column(mt, column, select,
+                                                 allocated_columns);
+            }
+        }
     }
 
     return NULL;
 }
 
-static void
-ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *s,
-                                  struct jsonrpc_msg *request)
+static struct json *
+ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s,
+                             struct json *params)
 {
-    struct jsonrpc_msg *reply;
+    struct ovsdb_jsonrpc_monitor *m = NULL;
+    struct json *monitor_id, *monitor_requests;
+    struct ovsdb_error *error = NULL;
+    struct shash_node *node;
+    struct json *json;
 
-    if (!strcmp(request->method, "transact")) {
-        reply = execute_transaction(s, request);
-    } else if (!strcmp(request->method, "get_schema")) {
-        reply = jsonrpc_create_reply(
-            ovsdb_schema_to_json(s->server->db->schema), request->id);
+    if (json_array(params)->n != 3) {
+        error = ovsdb_syntax_error(params, NULL, "invalid parameters");
+        goto error;
+    }
+    monitor_id = params->u.array.elems[1];
+    monitor_requests = params->u.array.elems[2];
+    if (monitor_requests->type != JSON_OBJECT) {
+        error = ovsdb_syntax_error(monitor_requests, NULL,
+                                   "monitor-requests must be object");
+        goto error;
+    }
+
+    if (ovsdb_jsonrpc_monitor_find(s, monitor_id)) {
+        error = ovsdb_syntax_error(monitor_id, NULL, "duplicate monitor ID");
+        goto error;
+    }
+
+    m = xzalloc(sizeof *m);
+    ovsdb_replica_init(&m->replica, &ovsdb_jsonrpc_replica_class);
+    ovsdb_add_replica(s->remote->server->up.db, &m->replica);
+    m->session = s;
+    hmap_insert(&s->monitors, &m->node, json_hash(monitor_id, 0));
+    m->monitor_id = json_clone(monitor_id);
+    shash_init(&m->tables);
+
+    SHASH_FOR_EACH (node, json_object(monitor_requests)) {
+        const struct ovsdb_table *table;
+        struct ovsdb_jsonrpc_monitor_table *mt;
+        size_t allocated_columns;
+        const struct json *mr_value;
+        size_t i;
+
+        table = ovsdb_get_table(s->remote->server->up.db, node->name);
+        if (!table) {
+            error = ovsdb_syntax_error(NULL, NULL,
+                                       "no table named %s", node->name);
+            goto error;
+        }
+
+        mt = xzalloc(sizeof *mt);
+        mt->table = table;
+        shash_add(&m->tables, table->schema->name, mt);
+
+        /* Parse columns. */
+        mr_value = node->data;
+        allocated_columns = 0;
+        if (mr_value->type == JSON_ARRAY) {
+            const struct json_array *array = &mr_value->u.array;
+
+            for (i = 0; i < array->n; i++) {
+                error = ovsdb_jsonrpc_parse_monitor_request(
+                    mt, array->elems[i], &allocated_columns);
+                if (error) {
+                    goto error;
+                }
+            }
+        } else {
+            error = ovsdb_jsonrpc_parse_monitor_request(
+                mt, mr_value, &allocated_columns);
+            if (error) {
+                goto error;
+            }
+        }
+
+        /* Check for duplicate columns. */
+        qsort(mt->columns, mt->n_columns, sizeof *mt->columns,
+              compare_ovsdb_jsonrpc_monitor_column);
+        for (i = 1; i < mt->n_columns; i++) {
+            if (mt->columns[i].column == mt->columns[i - 1].column) {
+                error = ovsdb_syntax_error(mr_value, NULL, "column %s "
+                                           "mentioned more than once",
+                                           mt->columns[i].column->name);
+                goto error;
+            }
+        }
+    }
+
+    return ovsdb_jsonrpc_monitor_get_initial(m);
+
+error:
+    if (m) {
+        ovsdb_remove_replica(s->remote->server->up.db, &m->replica);
+    }
+
+    json = ovsdb_error_to_json(error);
+    ovsdb_error_destroy(error);
+    return json;
+}
+
+static struct jsonrpc_msg *
+ovsdb_jsonrpc_monitor_cancel(struct ovsdb_jsonrpc_session *s,
+                             struct json_array *params,
+                             const struct json *request_id)
+{
+    if (params->n != 1) {
+        return jsonrpc_create_error(json_string_create("invalid parameters"),
+                                    request_id);
     } else {
-        reply = jsonrpc_create_error(json_string_create("unknown method"),
-                                     request->id);
+        struct ovsdb_jsonrpc_monitor *m;
+
+        m = ovsdb_jsonrpc_monitor_find(s, params->elems[0]);
+        if (!m) {
+            return jsonrpc_create_error(json_string_create("unknown monitor"),
+                                        request_id);
+        } else {
+            ovsdb_remove_replica(s->remote->server->up.db, &m->replica);
+            return jsonrpc_create_reply(json_object_create(), request_id);
+        }
     }
+}
 
-    if (reply) {
-        jsonrpc_msg_destroy(request);
-        jsonrpc_send(s->rpc, reply);
+static void
+ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *s)
+{
+    struct ovsdb_jsonrpc_monitor *m, *next;
+
+    HMAP_FOR_EACH_SAFE (m, next, node, &s->monitors) {
+        ovsdb_remove_replica(s->remote->server->up.db, &m->replica);
     }
 }
 
+static struct ovsdb_jsonrpc_monitor *
+ovsdb_jsonrpc_monitor_cast(struct ovsdb_replica *replica)
+{
+    assert(replica->class == &ovsdb_jsonrpc_replica_class);
+    return CONTAINER_OF(replica, struct ovsdb_jsonrpc_monitor, replica);
+}
+
+struct ovsdb_jsonrpc_monitor_aux {
+    bool initial;               /* Sending initial contents of table? */
+    const struct ovsdb_jsonrpc_monitor *monitor;
+    struct json *json;          /* JSON for the whole transaction. */
+
+    /* Current table.  */
+    struct ovsdb_jsonrpc_monitor_table *mt;
+    struct json *table_json;    /* JSON for table's transaction. */
+};
+
+static bool
+any_reportable_change(const struct ovsdb_jsonrpc_monitor_table *mt,
+                      const unsigned long int *changed)
+{
+    size_t i;
+
+    for (i = 0; i < mt->n_columns; i++) {
+        const struct ovsdb_jsonrpc_monitor_column *c = &mt->columns[i];
+        unsigned int idx = c->column->index;
+
+        if (c->select & OJMS_MODIFY && bitmap_is_set(changed, idx)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+static bool
+ovsdb_jsonrpc_monitor_change_cb(const struct ovsdb_row *old,
+                                const struct ovsdb_row *new,
+                                const unsigned long int *changed,
+                                void *aux_)
+{
+    struct ovsdb_jsonrpc_monitor_aux *aux = aux_;
+    const struct ovsdb_jsonrpc_monitor *m = aux->monitor;
+    struct ovsdb_table *table = new ? new->table : old->table;
+    enum ovsdb_jsonrpc_monitor_selection type;
+    struct json *old_json, *new_json;
+    struct json *row_json;
+    char uuid[UUID_LEN + 1];
+    size_t i;
+
+    if (!aux->mt || table != aux->mt->table) {
+        aux->mt = shash_find_data(&m->tables, table->schema->name);
+        aux->table_json = NULL;
+        if (!aux->mt) {
+            /* We don't care about rows in this table at all.  Tell the caller
+             * to skip it.  */
+            return false;
+        }
+    }
+
+    type = (aux->initial ? OJMS_INITIAL
+            : !old ? OJMS_INSERT
+            : !new ? OJMS_DELETE
+            : OJMS_MODIFY);
+    if (!(aux->mt->select & type)) {
+        /* We don't care about this type of change (but do want to be called
+         * back for changes to other rows in the same table). */
+        return true;
+    }
+
+    if (type == OJMS_MODIFY && !any_reportable_change(aux->mt, changed)) {
+        /* Nothing of interest changed. */
+        return true;
+    }
+
+    old_json = new_json = NULL;
+    if (type & (OJMS_DELETE | OJMS_MODIFY)) {
+        old_json = json_object_create();
+    }
+    if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
+        new_json = json_object_create();
+    }
+    for (i = 0; i < aux->mt->n_columns; i++) {
+        const struct ovsdb_jsonrpc_monitor_column *c = &aux->mt->columns[i];
+        const struct ovsdb_column *column = c->column;
+        unsigned int idx = c->column->index;
+
+        if (!(type & c->select)) {
+            /* We don't care about this type of change for this particular
+             * column (but we will care about it for some other column). */
+            continue;
+        }
+
+        if ((type == OJMS_MODIFY && bitmap_is_set(changed, idx))
+            || type == OJMS_DELETE) {
+            json_object_put(old_json, column->name,
+                            ovsdb_datum_to_json(&old->fields[idx],
+                                                &column->type));
+        }
+        if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
+            json_object_put(new_json, column->name,
+                            ovsdb_datum_to_json(&new->fields[idx],
+                                                &column->type));
+        }
+    }
+
+    /* Create JSON object for transaction overall. */
+    if (!aux->json) {
+        aux->json = json_object_create();
+    }
+
+    /* Create JSON object for transaction on this table. */
+    if (!aux->table_json) {
+        aux->table_json = json_object_create();
+        json_object_put(aux->json, aux->mt->table->schema->name,
+                        aux->table_json);
+    }
+
+    /* Create JSON object for transaction on this row. */
+    row_json = json_object_create();
+    if (old_json) {
+        json_object_put(row_json, "old", old_json);
+    }
+    if (new_json) {
+        json_object_put(row_json, "new", new_json);
+    }
+
+    /* Add JSON row to JSON table. */
+    snprintf(uuid, sizeof uuid,
+             UUID_FMT, UUID_ARGS(ovsdb_row_get_uuid(new ? new : old)));
+    json_object_put(aux->table_json, uuid, row_json);
+
+    return true;
+}
+
 static void
-execute_cancel(struct ovsdb_jsonrpc_session *s, struct jsonrpc_msg *request)
+ovsdb_jsonrpc_monitor_init_aux(struct ovsdb_jsonrpc_monitor_aux *aux,
+                               const struct ovsdb_jsonrpc_monitor *m,
+                               bool initial)
 {
-    size_t hash = json_hash(request->id, 0);
-    struct ovsdb_jsonrpc_trigger *t;
+    aux->initial = initial;
+    aux->monitor = m;
+    aux->json = NULL;
+    aux->mt = NULL;
+    aux->table_json = NULL;
+}
 
-    t = ovsdb_jsonrpc_trigger_find(s, request->params, hash);
-    if (t) {
-        ovsdb_jsonrpc_trigger_complete(t);
+static struct ovsdb_error *
+ovsdb_jsonrpc_monitor_commit(struct ovsdb_replica *replica,
+                             const struct ovsdb_txn *txn,
+                             bool durable OVS_UNUSED)
+{
+    struct ovsdb_jsonrpc_monitor *m = ovsdb_jsonrpc_monitor_cast(replica);
+    struct ovsdb_jsonrpc_monitor_aux aux;
+
+    ovsdb_jsonrpc_monitor_init_aux(&aux, m, false);
+    ovsdb_txn_for_each_change(txn, ovsdb_jsonrpc_monitor_change_cb, &aux);
+    if (aux.json) {
+        struct jsonrpc_msg *msg;
+        struct json *params;
+
+        params = json_array_create_2(json_clone(aux.monitor->monitor_id),
+                                     aux.json);
+        msg = jsonrpc_create_notify("update", params);
+        jsonrpc_session_send(aux.monitor->session->js, msg);
     }
+
+    return NULL;
+}
+
+static struct json *
+ovsdb_jsonrpc_monitor_get_initial(const struct ovsdb_jsonrpc_monitor *m)
+{
+    struct ovsdb_jsonrpc_monitor_aux aux;
+    struct shash_node *node;
+
+    ovsdb_jsonrpc_monitor_init_aux(&aux, m, true);
+    SHASH_FOR_EACH (node, &m->tables) {
+        struct ovsdb_jsonrpc_monitor_table *mt = node->data;
+
+        if (mt->select & OJMS_INITIAL) {
+            struct ovsdb_row *row;
+
+            HMAP_FOR_EACH (row, hmap_node, &mt->table->rows) {
+                ovsdb_jsonrpc_monitor_change_cb(NULL, row, NULL, &aux);
+            }
+        }
+    }
+    return aux.json ? aux.json : json_object_create();
 }
 
 static void
-ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *s,
-                                 struct jsonrpc_msg *request)
+ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *replica)
 {
-    if (!strcmp(request->method, "cancel")) {
-        execute_cancel(s, request);
+    struct ovsdb_jsonrpc_monitor *m = ovsdb_jsonrpc_monitor_cast(replica);
+    struct shash_node *node;
+
+    json_destroy(m->monitor_id);
+    SHASH_FOR_EACH (node, &m->tables) {
+        struct ovsdb_jsonrpc_monitor_table *mt = node->data;
+        free(mt->columns);
+        free(mt);
     }
-    jsonrpc_msg_destroy(request);
+    shash_destroy(&m->tables);
+    hmap_remove(&m->session->monitors, &m->node);
+    free(m);
 }
+
+static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class = {
+    ovsdb_jsonrpc_monitor_commit,
+    ovsdb_jsonrpc_monitor_destroy
+};