=================================================== Open vSwitch Configuration Database Specification =================================================== Basic Notation -------------- OVSDB uses JSON, as defined by RFC 4627, for its schema format and its wire protocol format. The JSON implementation in Open vSwitch has the following limitations: - Null bytes (\u0000) are not allowed in strings. - Only UTF-8 encoding is supported. (RFC 4627 also mentions UTF-16BE, UTF-16LE, and UTF-32.) - RFC 4627 says that names within a JSON object should be unique. The Open vSwitch JSON parser discards all but the last value for a name that is specified more than once. The descriptions below use the following shorthand notations for JSON values. Additional notation is presented later. A JSON string. Any Unicode string is allowed, as specified by RFC 4627. Implementations may disallow null bytes. A JSON string matching [a-zA-Z_][a-zA-Z0-9_]*. s that begin with _ are reserved to the implementation and may not be used by the user. A JSON string that contains a version number that matches [0-9]+\.[0-9]+\.[0-9]+ A JSON true or false value. A JSON number. A JSON number with an integer value, within a certain range (currently -2**63...+2**63-1). Any JSON value. Any JSON value except null. A JSON object with the following members: "error": required "details": optional The value of the "error" member is a short string, specified in this document, that broadly indicates the class of the error. Most "error" strings are specific to contexts described elsewhere in this document, but the following "error" strings may appear in any context where an is permitted: "error": "resources exhausted" The operation requires more resources (memory, disk, CPU, etc.) than are currently available to the database server. "error": "I/O error" Problems accessing the disk, network, or other required resources prevented the operation from completing. Database implementations may use "error" strings not specified in this document to indicate errors that do not fit into any of the specified categories. Optionally, an may include a "details" member, whose value is a string that describes the error in more detail for the benefit of a human user or administrator. This document does not specify the format or content of the "details" string. An may also have other members that describe the error in more detail. This document does not specify the names or values of these members. Schema Format ------------- An Open vSwitch configuration database consists of a set of tables, each of which has a number of columns and zero or more rows. A schema is represented by , as described below. A JSON object with the following members: "name": required "version": required "cksum": optional "tables": {: , ...} required The "name" identifies the database as a whole. It must be provided to most JSON-RPC requests to identify the database being operated on. The value of "tables" is a JSON object whose names are table names and whose values are s. The "version" reports the version of the database schema. Because this is a recent addition to the schema format, OVSDB permits it to be omitted, but future versions of OVSDB will require it to be present. Open vSwitch semantics for "version" are described in ovs-vswitchd.conf.db(5). The "cksum" optionally reports an implementation-defined checksum for the database schema. A JSON object with the following members: "columns": {: , ...} required "maxRows": optional "isRoot": optional "indexes": [*] optional The value of "columns" is a JSON object whose names are column names and whose values are s. Every table has the following columns whose definitions are not included in the schema: "_uuid": This column, which contains exactly one UUID value, is initialized to a random value by the database engine when it creates a row. It is read-only, and its value never changes during the lifetime of a row. "_version": Like "_uuid", this column contains exactly one UUID value, initialized to a random value by the database engine when it creates a row, and it is read-only. However, its value changes to a new random value whenever any other field in the row changes. Furthermore, its value is ephemeral: when the database is closed and reopened, or when the database process is stopped and then started again, each "_version" also changes to a new random value. If "isRoot" is omitted or specified as false, then any given row in the table may exist only when there is at least one reference to it, with refType "strong", from a different row (in the same table or a different table). This is a "deferred" action: unreferenced rows in the table are deleted just before transaction commit. If "isRoot" is specified as true, then rows in the table exist independent of any references (they can be thought of as part of the "root set" in a garbage collector). For compatibility with schemas created before "isRoot" was introduced, if "isRoot" is omitted or false in every in a given , then every table is part of the root set. If "maxRows" is specified, as a positive integer, it limits the maximum number of rows that may be present in the table. This is a "deferred" constraint, enforced only at transaction commit time (see the "transact" request below). If "maxRows" is not specified, the size of the table is limited only by the resources available to the database server. "maxRows" constraints are enforced after unreferenced rows are deleted from tables with a false "isRoot". If "indexes" is specified, it must be an array of zero or more s. A is an array of one or more strings, each of which names a column. Each is a set of columns whose values, taken together within any given row, must be unique within the table. This is a "deferred" constraint, enforced only at transaction commit time, after unreferenced rows are deleted and dangling weak references are removed. Ephemeral columns may not be part of indexes. A JSON object with the following members: "type": required "ephemeral": optional "mutable": optional The "type" specifies the type of data stored in this column. If "ephemeral" is specified as true, then this column's values are not guaranteed to be durable; they may be lost when the database restarts. A column whose type (either key or value) is a strong reference to a table that is not part of the root set is always durable, regardless of this value. (Otherwise, restarting the database could lose entire rows.) If "mutable" is specified as false, then this column's values may not be modified after they are initially set with the "insert" operation. The type of a database column. Either an or a JSON object that describes the type of a database column, with the following members: "key": required "value": optional "min": optional "max": or "unlimited" optional If "min" or "max" is not specified, each defaults to 1. If "max" is specified as "unlimited", then there is no specified maximum number of elements, although the implementation will enforce some limit. After considering defaults, "min" must be exactly 0 or exactly 1, "max" must be at least 1, and "max" must be greater than or equal to "min". If "min" and "max" are both 1 and "value" is not specified, the type is the scalar type specified by "key". If "min" is not 1 or "max" is not 1, or both, and "value" is not specified, the type is a set of scalar type "key". If "value" is specified, the type is a map from type "key" to type "value". The type of a key or value in a database column. Either an or a JSON object with the following members: "type": required "enum": optional "minInteger": optional, integers only "maxInteger": optional, integers only "minReal": optional, reals only "maxReal": optional, reals only "minLength": optional, strings only "maxLength": optional, strings only "refTable": optional, uuids only "refType": "strong" or "weak" optional, only with "refTable" An by itself is equivalent to a JSON object with a single member "type" whose value is the . "enum" may be specified as a whose type is a set of one or more values specified for the member "type". If "enum" is specified, then the valid values of the are limited to those in the . "enum" is mutually exclusive with the following constraints. If "type" is "integer", then "minInteger" or "maxInteger" or both may also be specified, restricting the valid integer range. If both are specified, then the maxInteger must be greater than or equal to minInteger. If "type" is "real", then "minReal" or "maxReal" or both may also be specified, restricting the valid real range. If both are specified, then the maxReal must be greater than or equal to minReal. If "type" is "string", then "minLength" and "maxLength" or both may be specified, restricting the valid length of value strings. If both are specified, then maxLength must be greater than or equal to minLength. String length is measured in characters (not bytes or UTF-16 code units). If "type" is "uuid", then "refTable", if present, must be the name of a table within this database. If "refTable" is specified, then "refType" may also be specified. If "refTable" is set, the effect depends on "refType": - If "refType" is "strong" or if "refType" is omitted, the allowed UUIDs are limited to UUIDs for rows in the named table. - If "refType" is "weak", then any UUIDs are allowed, but UUIDs that do not correspond to rows in the named table will be automatically deleted. "refTable" constraints are "deferred" constraints: they are enforced only at transaction commit time (see the "transact" request below). The other contraints on are "immediate", enforced immediately by each operation. One of the strings "integer", "real", "boolean", "string", or "uuid", representing the specified scalar type. Wire Protocol ------------- The database wire protocol is implemented in JSON-RPC 1.0. We encourage use of JSON-RPC over stream connections instead of JSON-RPC over HTTP, for these reasons: * JSON-RPC is a peer-to-peer protocol, but HTTP is a client-server protocol, which is a poor match. Thus, JSON-RPC over HTTP requires the client to periodically poll the server to receive server requests. * HTTP is more complicated than stream connections and doesn't provide any corresponding advantage. * The JSON-RPC specification for HTTP transport is incomplete. We are using TCP port 6632 for the database JSON-RPC connection. The database wire protocol consists of the following JSON-RPC methods: list_dbs ........ Request object members: "method": "list_dbs" required "params": [] required "id": required Response object members: "result": [, ...] "error": null "id": same "id" as request This operation retrieves an array whose elements are s that name the databases that can be accessed over this JSON-RPC connection. get_schema .......... Request object members: "method": "get_schema" required "params": [] required "id": required Response object members: "result": "error": null "id": same "id" as request This operation retrieves a that describes hosted database . transact ........ Request object members: "method": "transact" required "params": [, *] required "id": required Response object members: "result": [*] "error": null "id": same "id" as request The "params" array for this method consists of a that identifies the database to which the transaction applies, followed by zero or more JSON objects, each of which represents a single database operation. The "Operations" section below describes the valid operations. The value of "id" must be unique among all in-flight transactions within the current JSON-RPC session. Otherwise, the server may return a JSON-RPC error. The database server executes each of the specified operations in the specified order, except that if an operation fails, then the remaining operations are not executed. The set of operations is executed as a single atomic, consistent, isolated transaction. The transaction is committed only if every operation succeeds. Durability of the commit is not guaranteed unless the "commit" operation, with "durable" set to true, is included in the operation set (see below). Regardless of whether errors occur, the response is always a JSON-RPC response with null "error" and a "result" member that is an array with the same number of elements as "params". Each element of the "result" array corresponds to the same element of the "params" array. The "result" array elements may be interpreted as follows: - A JSON object that does not contain an "error" member indicates that the operation completed successfully. The specific members of the object are specified below in the descriptions of individual operations. Some operations do not produce any results, in which case the object will have no members. - An , which indicates that the operation completed with an error. - A JSON null value indicates that the operation was not attempted because a prior operation failed. In general, "result" contains some number of successful results, possibly followed by an error, in turn followed by enough JSON null values to match the number of elements in "params". There is one exception: if all of the operations succeed, but the results cannot be committed, then "result" will have one more element than "params", with the additional element an . The possible "error" strings include at least the following: "error": "referential integrity violation" When the commit was attempted, a column's value referenced the UUID for a row that did not exist in the table named by the column's key or value "refTable" that has a "refType" of "strong". (This can be caused by inserting a row that references a nonexistent row, by deleting a row that is still referenced by another row, by specifying the UUID for a row in the wrong table, and other ways.) "error": "constraint violation" A column with a key or value "refTable" whose "refType" is "weak" became empty due to deletion(s) caused because the rows that it referenced were deleted (or never existed, if the column's row was inserted within the transaction), and this column is not allowed to be empty because its has a "min" of 1. "error": "constraint violation" The number of rows in a table exceeds the maximum number permitted by the table's "maxRows" value (see ). "error": "constraint violation" Two or more rows in a table had the same values in the columns that comprise an index. "error": "resources exhausted" "error": "I/O error" As described in the definition of above. If "params" contains one or more "wait" operations, then the transaction may take an arbitrary amount of time to complete. The database implementation must be capable of accepting, executing, and replying to other transactions and other JSON-RPC requests while a transaction or transactions containing "wait" operations are outstanding on the same or different JSON-RPC sessions. The section "Notation for the Wire Protocol" below describes additional notation for use with the wire protocol. After that, the "Operations" section describes each operation. cancel ...... Request object members: "method": "cancel" required "params": [the "id" for an outstanding request] required "id": null required Response object members: This JSON-RPC notification instructs the database server to immediately complete or cancel the "transact" request whose "id" is the same as the notification's "params" value. If the "transact" request can be completed immediately, then the server sends a response in the form described for "transact", above. Otherwise, the server sends a JSON-RPC error response of the following form: "result": null "error": "canceled" "id": the request "id" member The "cancel" notification itself has no reply. monitor ....... Request object members: "method": "monitor" required "params": [, , ] required "id": required is an object that maps from a table name to an array of objects. For backward compatibility, a single may be used instead of an array; it is treated as a single-element array. Each is an object with the following members: "columns": [*] optional "select": optional is an object with the following members: "initial": optional "insert": optional "delete": optional "modify": optional Response object members: "result": "error": null "id": same "id" as request This JSON-RPC request enables a client to replicate tables or subsets of tables within database . Each element of specifies a table to be replicated. The JSON-RPC response to the "monitor" includes the initial contents of each table, unless disabled (see below). Afterward, when changes to those tables are committed, the changes are automatically sent to the client using the "update" monitor notification. This monitoring persists until the JSON-RPC session terminates or until the client sends a "monitor_cancel" JSON-RPC request. Each describes how to monitor columns in a table: The circumstances in which an "update" notification is sent for a row within the table are determined by : If "initial" is omitted or true, every row in the table is sent as part of the reply to the "monitor" request. If "insert" is omitted or true, "update" notifications are sent for rows newly inserted into the table. If "delete" is omitted or true, "update" notifications are sent for rows deleted from the table. If "modify" is omitted or true, "update" notifications are sent whenever when a row in the table is modified. The "columns" member specifies the columns whose values are monitored. It must not contain duplicates. If "columns" is omitted, all columns in the table, except for "_uuid", are monitored. If there is more than one in an array of them, then each in the array should specify both "columns" and "select", and the "columns" must be non-overlapping sets. The "result" in the JSON-RPC response to the "monitor" request is a object (see below) that contains the contents of the tables for which "initial" rows are selected. If no tables' initial contents are requested, then "result" is an empty object. update ...... Notification object members: "method": "update" "params": [, ] "id": null The in "params" is the same as the value passed as the in "params" for the "monitor" request. is an object that maps from a table name to a . A is an object that maps from the row's UUID (as a 36-byte string) to a object. A is an object with the following members: "old": present for "delete" and "modify" updates "new": present for "initial", "insert", and "modify" updates This JSON-RPC notification is sent from the server to the client to tell it about changes to a monitored table (or the initial state of a modified table). Each table in which one or more rows has changed (or whose initial view is being presented) is represented in "updates". Each row that has changed (or whose initial view is being presented) is represented in its as a member with its name taken from the row's _uuid member. The corresponding value is a : The "old" member is present for "delete" and "modify" updates. For "delete" updates, each monitored column is included. For "modify" updates, the prior value of each monitored column whose value has changed is included (monitored columns that have not changed are represented in "new"). The "new" member is present for "initial", "insert", and "modify" updates. For "initial" and "insert" updates, each monitored column is included. For "modify" updates, the new value of each monitored column is included. monitor_cancel .............. Request object members: "method": "monitor_cancel" required "params": [] required "id": required Response object members: "result": {} "error": null "id": the request "id" member Cancels the ongoing table monitor request, identified by the in "params" matching the in "params" for an ongoing "monitor" request. No more "update" messages will be sent for this table monitor. lock operations ............... Request object members: "method": "lock", "steal", or "unlock" required "params": [] required "id": required Response object members: "result": {"locked": } for "lock" "result": {"locked": true} for "steal" "result": {} for "unlock" "error": null "id": same "id" as request Performs an operation on a "lock" object. The database server supports an arbitrary number of locks, each of which is identified by a client-defined id (given in "params"). At any given time, each lock may have at most one owner. The locking operation depends on "method": - "lock": The database will assign this client ownership of the lock as soon as it becomes available. When multiple clients request the same lock, they will receive it in first-come, first served order. - "steal": The database immediately assigns this client ownership of the lock. If there is an existing owner, it loses ownership. - "unlock": If the client owns the lock, releases it. If the client is waiting to obtain the lock, cancels the request and stops waiting. (Closing or otherwise disconnecting a database client connection unlocks all of its locks.) For any given lock, the client must alternate "lock" or "steal" operations with "unlock" operations. That is, if the previous operation on a lock was "lock" or "steal", it must be followed by an "unlock" operation, and vice versa. For a "lock" operation, the "locked" member in the response object is true if the lock has already been acquired, false if another client holds the lock and the client's request for it was queued. In the latter case, the client will be notified later with a "locked" message when acquisition succeeds. These requests complete and send a response quickly, without waiting. The "locked" and "stolen" notifications (see below) report asynchronous changes to ownership. The scope of a lock is a database server, not a database hosted by that server. A naming convention, such as "__", can effectively limit the scope of a lock to a particular database. locked ...... Notification object members: "method": "locked" "params": [] "id": null Notifies the client that a "lock" operation that it previously requested has succeeded. The client now owns the lock named in "params". The database server sends this notification after the reply to the corresponding "lock" request (but only if the "locked" member of the response was false), and before the reply to the client's subsequent "unlock" request. stolen ...... Notification object members: "method": "stolen" "params": [] "id": null Notifies the client that owns a lock that another database client has stolen ownership of the lock. The client no longer owns the lock named in "params". The client must still issue an "unlock" request before performing any subsequent "lock" or "steal" operation on the lock. If the client originally obtained the lock through a "lock" request, then it will automatically regain the lock later after the client that stole it releases it. (The database server will send the client a "locked" notification at that point to let it know.) If the client originally obtained the lock through a "steal" request, the database server won't automatically reassign it ownership of the lock when it later becomes available. To regain ownership, the client must "unlock" and then "lock" or "steal" the lock again. echo .... Request object members: "method": "echo" required "params": JSON array with any contents required "id": required Response object members: "result": same as "params" "error": null "id": the request "id" member Both the JSON-RPC client and the server must implement this request. This JSON-RPC request and response can be used to implement connection keepalives, by allowing the server to check that the client is still there or vice versa. Notation for the Wire Protocol ------------------------------ An that names a database. The valid s can be obtained using a "list-db" request. The is taken from the "name" member of . An that names a table. An that names a table column. A JSON object that describes a table row or a subset of a table row. Each member is the name of a table column paired with the of that column. A JSON value that represents the value of a column in a table row, one of , a , or a . A JSON value that represents a scalar value for a column, one of , , , , . Either an , representing a set with exactly one element, or a 2-element JSON array that represents a database set value. The first element of the array must be the string "set" and the second element must be an array of zero or more s giving the values in the set. All of the s must have the same type. A 2-element JSON array that represents a database map value. The first element of the array must be the string "map" and the second element must be an array of zero or more s giving the values in the map. All of the s must have the same key and value types. (JSON objects are not used to represent because JSON only allows string names in an object.) A 2-element JSON array that represents a pair within a database map. The first element is an that represents the key, the second element is an that represents the value. A 2-element JSON array that represents a UUID. The first element of the array must be the string "uuid" and the second element must be a 36-character string giving the UUID in the format described by RFC 4122. For example, the following represents the UUID 550e8400-e29b-41d4-a716-446655440000: ["uuid", "550e8400-e29b-41d4-a716-446655440000"] A 2-element JSON array that represents the UUID of a row inserted in an "insert" operation within the same transaction. The first element of the array must be the string "named-uuid" and the second element should be the specified as the "uuid-name" for an "insert" operation within the same transaction. For example, if an "insert" operation within this transaction specifies a "uuid-name" of "myrow", the following represents the UUID created by that operation: ["named-uuid", "myrow"] A may be used anywhere a is valid. A 3-element JSON array of the form [, , ] that represents a test on a column value. Except as otherwise specified below, must have the same type as . The meaning depends on the type of : integer real must be "<", "<=", "==", "!=", ">=", ">", "includes", or "excludes". The test is true if the column's value satisfies the relation , e.g. if the column has value 1 and is 2, the test is true if is "<", "<=" or "!=", but not otherwise. "includes" is equivalent to "=="; "excludes" is equivalent to "!=". boolean string uuid must be "!=", "==", "includes", or "excludes". If is "==" or "includes", the test is true if the column's value equals . If is "!=" or "excludes", the test is inverted. set map must be "!=", "==", "includes", or "excludes". If is "==", the test is true if the column's value contains exactly the same values (for sets) or pairs (for maps). If is "!=", the test is inverted. If is "includes", the test is true if the column's value contains all of the values (for sets) or pairs (for maps) in . The column's value may also contain other values or pairs. If is "excludes", the test is true if the column's value does not contain any of the values (for sets) or pairs (for maps) in . The column's value may contain other values or pairs not in . If is "includes" or "excludes", then the required type of is slightly relaxed, in that it may have fewer than the minimum number of elements specified by the column's type. If is "excludes", then the required type is additionally relaxed in that may have more than the maximum number of elements specified by the column's type. One of "<", "<=", "==", "!=", ">=", ">", "includes", "excludes". A 3-element JSON array of the form [, , ] that represents a change to a column value. Except as otherwise specified below, must have the same type as . The meaning depends on the type of : integer real must be "+=", "-=", "*=", "/=" or (integer only) "%=". The value of is changed to the sum, difference, product, quotient, or remainder, respectively, of and . Constraints on are ignored when parsing . boolean string uuid No valid s are currently defined for these types. set Any valid for the set's element type may be applied to the set, in which case the mutation is applied to each member of the set individually. must be a scalar value of the same type as the set's element type, except that contraints are ignored. If is "insert", then each of the values in the set in is added to if it is not already present. The required type of is slightly relaxed, in that it may have fewer than the minimum number of elements specified by the column's type. If is "delete", then each of the values in the set in is removed from if it is present there. The required type is slightly relaxed in that may have more or less than the maximum number of elements specified by the column's type. map must be "insert" or "delete". If is "insert", then each of the key-value pairs in the map in is added to only if its key is not already present. The required type of is slightly relaxed, in that it may have fewer than the minimum number of elements specified by the column's type. If is "delete", then may have the same type as (a map type) or it may be a set whose element type is the same as 's key type: - If is a map, the mutation deletes each key-value pair in whose key and value equal one of the key-value pairs in . - If is a set, the mutation deletes each key-value pair in whose key equals one of the values in . For "delete", may have any number of elements, regardless of restrictions on the number of elements in . One of "+=", "-=", "*=", "/=", "%=", "insert", "delete". Operations ---------- Each of the available operations is described below. insert ...... Request object members: "op": "insert" required "table":
required "row": required "uuid-name": optional Result object members: "uuid": Semantics: Inserts "row" into "table". If "row" does not specify values for all the columns in "table", those columns receive default values. The default value for a column depends on its type. The default for a column whose specifies a "min" of 0 is an empty set or empty map. Otherwise, the default is a single value or a single key-value pair, whose value(s) depend on its : - "integer" or "real": 0 - "boolean": false - "string": "" (the empty string) - "uuid": 00000000-0000-0000-0000-000000000000 The new row receives a new, randomly generated UUID. If "uuid-name" is supplied, then it is an error if is not unique among the "uuid-name"s supplied on all the "insert" operations within this transaction. The UUID for the new row is returned as the "uuid" member of the result. Errors: "error": "duplicate uuid-name" The same "uuid-name" appears on another "insert" operation within this transaction. "error": "constraint violation" One of the values in "row" does not satisfy the immediate constraints for its column's . This error will occur for columns that are not explicitly set by "row" if the default value does not satisfy the column's constraints. select ...... Request object members: "op": "select" required "table":
required "where": [*] required "columns": [*] optional Result object members: "rows": [*] Semantics: Searches "table" for rows that match all the conditions specified in "where". If "where" is an empty array, every row in "table" is selected. The "rows" member of the result is an array of objects. Each object corresponds to a matching row, with each column specified in "columns" as a member, the column's name as the member name and its value as the member value. If "columns" is not specified, all the table's columns are included. If two rows of the result have the same values for all included columns, only one copy of that row is included in "rows". Specifying "_uuid" within "columns" will avoid dropping duplicates, since every row has a unique UUID. The ordering of rows within "rows" is unspecified. update ...... Request object members: "op": "update" required "table":
required "where": [*] required "row": required Result object members: "count": Semantics: Updates rows in a table. Searches "table" for rows that match all the conditions specified in "where". For each matching row, changes the value of each column specified in "row" to the value for that column specified in "row". The "_uuid" and "_version" columns of a table may not be directly updated with this operation. Columns designated read-only in the schema also may not be updated. The "count" member of the result specifies the number of rows that matched. Errors: "error": "constraint violation" One of the values in "row" does not satisfy the immediate constraints for its column's . mutate ...... Request object members: "op": "mutate" required "table":
required "where": [*] required "mutations": [*] required Result object members: "count": Semantics: Mutates rows in a table. Searches "table" for rows that match all the conditions specified in "where". For each matching row, mutates its columns as specified by each in "mutations", in the order specified. The "_uuid" and "_version" columns of a table may not be directly modified with this operation. Columns designated read-only in the schema also may not be updated. The "count" member of the result specifies the number of rows that matched. Errors: "error": "domain error" The result of the mutation is not mathematically defined, e.g. division by zero. "error": "range error" The result of the mutation is not representable within the database's format, e.g. an integer result outside the range INT64_MIN...INT64_MAX or a real result outside the range -DBL_MAX...DBL_MAX. "error": "constraint violation" The mutation caused the column's value to violate a constraint, e.g. it caused a column to have more or fewer values than are allowed, an arithmetic operation caused a set or map to have duplicate elements, or it violated a constraint specified by a column's . delete ...... Request object members: "op": "delete" required "table":
required "where": [*] required Result object members: "count": Semantics: Deletes all the rows from "table" that match all the conditions specified in "where". The "count" member of the result specifies the number of deleted rows. wait .... Request object members: "op": "wait" required "timeout": optional "table":
required "where": [*] required "columns": [*] required "until": "==" or "!=" required "rows": [*] required Result object members: none Semantics: Waits until a condition becomes true. If "until" is "==", checks whether the query on "table" specified by "where" and "columns", which is evaluated in the same way as specified for "select", returns the result set specified by "rows". If it does, then the operation completes successfully. Otherwise, the entire transaction rolls back. It is automatically restarted later, after a change in the database makes it possible for the operation to succeed. The client will not receive a response until the operation permanently succeeds or fails. If "until" is "!=", the sense of the test is negated. That is, as long as the query on "table" specified by "where" and "columns" returns "rows", the transaction will be rolled back and restarted later. If "timeout" is specified, then the transaction aborts after the specified number of milliseconds. The transaction is guaranteed to be attempted at least once before it aborts. A "timeout" of 0 will abort the transaction on the first mismatch. Errors: "error": "not supported" One or more of the columns in this table do not support triggers. This error will not occur if "timeout" is 0. "error": "timed out" The "timeout" was reached before the transaction was able to complete. commit ...... Request object members: "op": "commit" required "durable": required Result object members: none Semantics: If "durable" is specified as true, then the transaction, if it commits, will be stored durably (to disk) before the reply is sent to the client. Errors: "error": "not supported" When "durable" is true, this database implementation does not support durable commits. abort ..... Request object members: "op": "abort" required Result object members: (never succeeds) Semantics: Aborts the transaction with an error. This may be useful for testing. Errors: "error": "aborted" This operation always fails with this error. comment ....... Request object members: "op": "comment" required "comment": required Result object members: none Semantics: Provides information to a database administrator on the purpose of a transaction. The OVSDB server, for example, adds comments in transactions that modify the database to the database journal. assert ...... Request object members: "op": "assert" required "lock": required Result object members: none Semantics: If the client does not own the lock named , aborts the transaction. Errors: "error": "not owner" The client does not own the named lock.