JSON Reference

As Avatica uses JSON to serialize messages sent over an HTTP transport, the RPC layer is agnostic of the language used by a client. While the Avatica server is written in Java, this enables clients to interact with the server using any language instead of being limited to Java.

A specification of the JSON request and response objects are documented below. Programmatic bindings for these JSON objects are only available in Java. For support outside of Java, see the Protocol Buffer bindings

Index

Requests

The collection of all JSON objects accepted as requests to Avatica. All Requests include a request attribute which uniquely identifies the concrete Request from all other Requests.

CatalogsRequest

This request is used to fetch the available catalog names in the database.

{
  "request": "getCatalogs",
  "connectionId": "000000-0000-0000-00000000"
}

connectionId (required string) The identifier of the connection to use.

CloseConnectionRequest

This request is used to close the Connection object in the Avatica server identified by the given IDs.

{
  "request": "closeConnection",
  "connectionId": "000000-0000-0000-00000000"
}

connectionId (required string) The identifier of the connection to close.

CloseStatementRequest

This request is used to close the Statement object in the Avatica server identified by the given IDs.

{
  "request": "closeStatement",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345
}

connectionId (required string) The identifier of the connection to which the statement belongs.

statementId (required integer) The identifier of the statement to close.

ColumnsRequest

This request is used to fetch columns in the database given some optional filtering criteria.

{
  "request": "getColumns",
  "connectionId": "000000-0000-0000-00000000",
  "catalog": "catalog",
  "schemaPattern": "schema_pattern.*",
  "tableNamePattern": "table_pattern.*",
  "columnNamePattern": "column_pattern.*"
}

connectionId (required string) The identifier of the connection on which to fetch the columns.

catalog (optional string) The name of a catalog to limit returned columns.

schemaPattern (optional string) A Java Pattern against schemas to limit returned columns.

tableNamePattern (optional string) A Java Pattern against table names to limit returned columns.

columnNamePattern (optional string) A Java Pattern against column names to limit returned columns.

CommitRequest

This request is used to issue a commit on the Connection in the Avatica server identified by the given ID.

{
  "request": "commit",
  "connectionId": "000000-0000-0000-00000000"
}

connectionId (required string) The identifier of the connection on which to invoke commit.

ConnectionSyncRequest

This request is used to ensure that the client and server have a consistent view of the database properties.

{
  "request": "connectionSync",
  "connectionId": "000000-0000-0000-00000000",
  "connProps": ConnectionProperties
}

connectionId (required string) The identifier of the connection to synchronize.

connProps (optional nested object) A ConnectionProperties object to synchronize between the client and server.

CreateStatementRequest

This request is used to create a new Statement in the Avatica server.

{
  "request": "createStatement",
  "connectionId": "000000-0000-0000-00000000"
}

connectionId (required string) The identifier of the connection to use in creating a statement.

DatabasePropertyRequest

This request is used to fetch all database properties.

{
  "request": "databaseProperties",
  "connectionId": "000000-0000-0000-00000000"
}

connectionId (required string) The identifier of the connection to use when fetching the database properties.

ExecuteBatchRequest

This request is used to execute a batch of updates on a PreparedStatement.

{
  "request": "executeBatch",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345,
  "parameterValues": [ [ TypedValue, TypedValue, ... ], [ TypedValue, TypedValue, ...], ... ]
}

connectionId (required string) The identifier of the connection to use when fetching the database properties.

statementId (required integer) The identifier of the statement created using the above connection.

parameterValues (required array of array) An array of arrays of TypedValue’s. Each element in the array is an update to a row, while the outer array represents the entire “batch” of updates.

ExecuteRequest

This request is used to execute a PreparedStatement, optionally with values to bind to the parameters in the Statement.

{
  "request": "execute",
  "statementHandle": StatementHandle,
  "parameterValues": [TypedValue, TypedValue, ... ],
  "maxRowCount": 100
}

statementHandle (required object) A StatementHandle object.

parameterValues (optional array of nested objects) The TypedValue for each parameter on the prepared statement.

maxRowCount (required long) The maximum number of rows returned in the response.

FetchRequest

This request is used to fetch a batch of rows from a Statement previously created.

{
  "request": "fetch",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345,
  "offset": 0,
  "fetchMaxRowCount": 100
}

connectionId (required string) The identifier of the connection to use.

statementId (required integer) The identifier of the statement created using the above connection.

offset (required integer) The positional offset into a result set to fetch.

fetchMatchRowCount (required integer) The maximum number of rows to return in the response to this request.

OpenConnectionRequest

This request is used to open a new Connection in the Avatica server.

{
  "request": "openConnection",
  "connectionId": "000000-0000-0000-00000000",
  "info": {"key":"value", ...}
}

connectionId (required string) The identifier of the connection to open in the server.

info (optional string-to-string map) A Map containing properties to include when creating the Connection.

PrepareAndExecuteBatchRequest

This request is used as short-hand to create a Statement and execute an batch of SQL commands in that Statement.

{
  "request": "prepareAndExecuteBatch",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345,
  "sqlCommands": [ "SQL Command", "SQL Command", ... ]
}

connectionId (required string) The identifier for the connection to use.

statementId (required integer) The identifier for the statement created by the above connection to use.

sqlCommands (required array of strings) An array of SQL commands

PrepareAndExecuteRequest

This request is used as a short-hand for create a Statement and fetching the first batch of results in a single call without any parameter substitution.

{
  "request": "prepareAndExecute",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345,
  "sql": "SELECT * FROM table",
  "maxRowCount": 100,
}

connectionId (required string) The identifier for the connection to use.

statementId (required integer) The identifier for the statement created by the above connection to use.

sql (required string) A SQL statement

maxRowCount (required long) The maximum number of rows returned in the response.

PrepareRequest

This request is used to create create a new Statement with the given query in the Avatica server.

{
  "request": "prepare",
  "connectionId": "000000-0000-0000-00000000",
  "sql": "SELECT * FROM table",
  "maxRowCount": 100,
}

connectionId (required string) The identifier for the connection to use.

sql (required string) A SQL statement

maxRowCount (required long) The maximum number of rows returned in the response.

SyncResultsRequest

This request is used to reset a ResultSet’s iterator to a specific offset in the Avatica server.

{
  "request": "syncResults",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345,
  "state": QueryState,
  "offset": 200
}

connectionId (required string) The identifier for the connection to use.

statementId (required integer) The identifier for the statement to use.

state (required object) The QueryState object.

offset (required long) The offset into the ResultSet to seek to.

RollbackRequest

This request is used to issue a rollback on the Connection in the Avatica server identified by the given ID.

{
  "request": "rollback",
  "connectionId": "000000-0000-0000-00000000"
}

connectionId (required string) The identifier for the connection on which to invoke rollback.

SchemasRequest

This request is used to fetch the schemas matching the provided criteria in the database.

{
  "request": "getSchemas",
  "connectionId": "000000-0000-0000-00000000",
  "catalog": "name",
  "schemaPattern": "pattern.*"
}

connection_id The identifier for the connection to fetch schemas from.

catalog (optional string) The name of the catalog to fetch the schema from.

schemaPattern (optional string) A Java pattern of schemas to fetch.

TableTypesRequest

This request is used to fetch the table types available in this database.

{
  "request": "getTableTypes",
  "connectionId": "000000-0000-0000-00000000"
}

connectionId The identifier of the connection to fetch the table types from.

TablesRequest

This request is used to fetch the tables available in this database filtered by the provided criteria.

{
  "request": "getTables",
  "connectionId": "000000-0000-0000-00000000",
  "catalog": "catalog_name",
  "schemaPattern": "schema_pattern.*",
  "tableNamePattern": "table_name_pattern.*",
  "typeList": [ "TABLE", "VIEW", ... ]
}

catalog (optional string) The name of a catalog to restrict fetched tables.

connectionId The identifier of the connection to fetch the tables from.

schemaPattern (optional string) A Java Pattern representing schemas to include in fetched tables.

tableNamePattern (optional string) A Java Pattern representing table names to include in fetched tables.

typeList (optional array of string) A list of table types used to restrict fetched tables.

TypeInfoRequest

This request is used to fetch the types available in this database.

{
  "request": "getTypeInfo",
  "connectionId": "000000-0000-0000-00000000"
}

connectionId The identifier of the connection to fetch the types from.

Responses

The collection of all JSON objects returned as responses from Avatica. All Responses include a response attribute which uniquely identifies the concrete Response from all other Responses.

CloseConnectionResponse

A response to the CloseConnectionRequest.

{
  "response": "closeConnection",
  "rpcMetadata": RpcMetadata
}

rpcMetadata Server metadata about this call.

CloseStatementResponse

A response to the CloseStatementRequest.

{
  "response": "closeStatement",
  "rpcMetadata": RpcMetadata
}

rpcMetadata Server metadata about this call.

CommitResponse

A response to the CommitRequest.

{
  "response": "commit"
}

There are no extra attributes on this Response.

ConnectionSyncResponse

A response to the ConnectionSyncRequest. Properties included in the response are those of the Connection in the Avatica server.

{
  "response": "connectionSync",
  "connProps": ConnectionProperties,
  "rpcMetadata": RpcMetadata
}

connProps The ConnectionProperties that were synchronized.

rpcMetadata Server metadata about this call.

CreateStatementResponse

A response to the CreateStatementRequest. The ID of the statement that was created is included in the response. Clients will use this statementId in subsequent calls.

{
  "response": "createStatement",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345,
  "rpcMetadata": RpcMetadata
}

connectionId The identifier for the connection used to create the statement.

statementId The identifier for the created statement.

rpcMetadata Server metadata about this call.

DatabasePropertyResponse

A response to the DatabasePropertyRequest. See DatabaseProperty for information on the available property keys.

{
  "response": "databaseProperties",
  "map": { DatabaseProperty: Object, DatabaseProperty: Object, ... },
  "rpcMetadata": RpcMetadata
}

map A map of DatabaseProperty to value of that property. The value may be some primitive type or an array of primitive types.

rpcMetadata Server metadata about this call.

ErrorResponse

A response when an error was caught executing a request. Any request may return this response.

{
  "response": "error",
  "exceptions": [ "stacktrace", "stacktrace", ... ],
  "errorMessage": "The error message",
  "errorCode": 42,
  "sqlState": "ABC12",
  "severity": AvaticaSeverity,
  "rpcMetadata": RpcMetadata
}

exceptions A list of stringified Java StackTraces.

errorMessage A human-readable error message.

errorCode A numeric code for this error.

sqlState A five character alphanumeric code for this error.

severity An AvaticaSeverity object which denotes how critical the error is.

rpcMetadata Server metadata about this call.

ExecuteBatchResponse

A response to ExecuteBatchRequest and PrepareAndExecuteRequest which encapsulates the update counts for a batch of updates.

{
  "response": "executeBatch",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345,
  "updateCounts": [ 1, 1, 0, 1, ... ],
  "missingStatement": false,
  "rpcMetadata": RpcMetadata
}

connectionId The identifier for the connection used to create the statement.

statementId The identifier for the created statement.

updateCounts An array of integers corresponding to each update contained in the batch that was executed.

missingStatement True if the operation failed because the Statement is not cached in the server, false otherwise.

rpcMetadata Server metadata about this call.

ExecuteResponse

A response to the ExecuteRequest which contains the results for a metadata query.

{
  "response": "executeResults",
  "resultSets": [ ResultSetResponse, ResultSetResponse, ... ],
  "missingStatement": false,
  "rpcMetadata": RpcMetadata
}

resultSets An array of ResultSetResponses.

missingStatement A boolean which denotes if the request failed due to a missing Statement.

rpcMetadata Server metadata about this call.

FetchResponse

A response to the FetchRequest which contains the request for the query.

{
  "response": "fetch",
  "frame": Frame,
  "missingStatement": false,
  "missingResults": false,
  "rpcMetadata": RpcMetadata
}

frame A Frame containing the results of the fetch.

missingStatement A boolean which denotes if the request failed due to a missing Statement.

missingResults A boolean which denotes if the request failed due to a missing ResultSet.

rpcMetadata Server metadata about this call.

OpenConnectionResponse

A response to the OpenConnectionRequest. The ID for the connection that the client should use in subsequent calls was provided by the client in the request.

{
  "response": "openConnection",
  "rpcMetadata": RpcMetadata
}

rpcMetadata Server metadata about this call.

PrepareResponse

A response to the PrepareRequest. This response includes a StatementHandle which clients must use to fetch the results from the Statement.

{
  "response": "prepare",
  "statement": StatementHandle,
  "rpcMetadata": RpcMetadata
}

statement A StatementHandle object.

rpcMetadata Server metadata about this call.

ResultSetResponse

A response which contains the results and type details from a query.

{
  "response": "resultSet",
  "connectionId": "000000-0000-0000-00000000",
  "statementId": 12345,
  "ownStatement": true,
  "signature": Signature,
  "firstFrame": Frame,
  "updateCount": 10,
  "rpcMetadata": RpcMetadata
}

connectionId The identifier for the connection used to generate this response.

statementId The identifier for the statement used to generate this response.

ownStatement Whether the result set has its own dedicated statement. If true, the server must automatically close the statement when the result set is closed. This is used for JDBC metadata result sets, for instance.

signature A non-optional nested object Signature

firstFrame A optional nested object Frame

updateCount A number which is always -1 for normal result sets. Any other value denotes a “dummy” result set that only contains this count and no additional data.

rpcMetadata Server metadata about this call.

RollbackResponse

A response to the RollBackRequest.

{
  "response": "rollback"
}

There are no extra attributes on this Response.

SyncResultsResponse

A response to the SyncResultsRequest. When moreResults is true, a FetchRequest should be issued to get the next batch of records. When missingStatement is true, the statement must be re-created using PrepareRequest or the appropriate Request for a DDL request (e.g. CatalogsRequest or SchemasRequest).

{
  "response": "syncResults",
  "moreResults": true,
  "missingStatement": false,
  "rpcMetadata": RpcMetadata
}

moreResults A boolean which denotes if results exist for the ResultSet being “synced” per the request.

missingStatement A boolean which denotes if the statement for the ResultSet still exists.

rpcMetadata Server metadata about this call.

Miscellaneous

AvaticaParameter

This object describes the “simple”, or scalar, JDBC type representation of a column in a result. This does not include complex types such as arrays.

{
  "signed": true,
  "precision": 10,
  "scale": 2,
  "parameterType": 8,
  "typeName": "integer",
  "className": "java.lang.Integer",
  "name": "number"
}

signed A boolean denoting whether the column is a signed numeric.

precision The maximum numeric precision supported by this column.

scale The maximum numeric scale supported by this column.

parameterType An integer corresponding to the JDBC Types class denoting the column’s type.

typeName The JDBC type name for this column.

className The Java class backing the JDBC type for this column.

name The name of the column.

AvaticaSeverity

This enumeration describes the various levels of concern for an error in the Avatica server.

One of:

UNKNOWN
FATAL
ERROR
WARNING

AvaticaType

This object describes a simple or complex type for a column. Complex types will contain additional information in the component or columns attribute which describe the nested types of the complex parent type.

{
  "type": "scalar",
  "id": "identifier",
  "name": "column",
  "rep": Rep,
  "columns": [ ColumnMetaData, ColumnMetaData, ... ],
  "component": AvaticaType
}

type One of: scalar, array, struct.

id A numeric value corresponding to the type of the object per the JDBC Types class.

name The readable name of the JDBC type.

rep A nested Rep object used by Avatica to hold additional type information.

columns For STRUCT types, a list of the columns contained in that STRUCT.

component For ARRAY types, the type of the elements contained in that ARRAY.

ColumnMetaData

This object represents the JDBC ResultSetMetaData for a column.

{
  "ordinal": 0,
  "autoIncrement": true,
  "caseSensitive": true,
  "searchable": false,
  "currency": false,
  "nullable": 0,
  "signed": true,
  "displaySize": 20,
  "label": "Description",
  "columnName": "col1",
  "schemaName": "schema",
  "precision": 10,
  "scale": 2,
  "tableName": "table",
  "catalogName": "catalog",
  "type": AvaticaType,
  "readOnly": false,
  "writable": true,
  "definitelyWritable": true,
  "columnClassName": "java.lang.String"
}

ordinal A positional offset number.

autoIncrement A boolean denoting whether the column is automatically incremented.

caseSensitive A boolean denoting whether the column is case sensitive.

searchable A boolean denoting whether this column supports all WHERE search clauses.

currency A boolean denoting whether this column represents currency.

nullable A number denoting whether this column supports null values.

0 = No null values are allowed
1 = Null values are allowed
2 = It is unknown if null values are allowed

signed A boolean denoting whether the column is a signed numeric.

displaySize The character width of the column.

label A description for this column.

columnName The name of the column.

schemaName The schema to which this column belongs.

precision The maximum numeric precision supported by this column.

scale The maximum numeric scale supported by this column.

tableName The name of the table to which this column belongs.

catalogName The name of the catalog to which this column belongs.

type A nested AvaticaType representing the type of the column.

readOnly A boolean denoting whether the column is read-only.

writable A boolean denoting whether the column is possible to be updated.

definitelyWritable A boolean denoting whether the column definitely can be updated.

columnClassName The name of the Java class backing the column’s type.

ConnectionProperties

This object represents the properties for a given JDBC Connection.

{
  "connProps": "connPropsImpl",
  "autoCommit": true,
  "readOnly": true,
  "transactionIsolation": 0,
  "catalog": "catalog",
  "schema": "schema"
}

autoCommit (optional boolean) A boolean denoting if autoCommit is enabled for transactions.

readOnly (optional boolean) A boolean denoting if a JDBC connection is read-only.

transactionIsolation (optional integer) An integer which denotes the level of transactions isolation per the JDBC specification. This value is analogous to the values defined in java.sql.Connection.

0 = Transactions are not supported
1 = Dirty reads, non-repeatable reads and phantom reads may occur.
2 = Dirty reads are prevented, but non-repeatable reads and phantom reads may occur.
4 = Dirty reads and non-repeatable reads are prevented, but phantom reads may occur.
8 = Dirty reads, non-repeatable reads, and phantom reads are all prevented.

catalog (optional string) The name of the catalog to include when fetching connection properties.

schema (optional string) The name of the schema to include when fetching connection properties.

isDirty (internal boolean) A boolean used for internal purposes only (not required by the Avatica protocol). This field will be removed from the protocol in future releases.

CursorFactory

This object represents the information required to cast untyped objects into the necessary type for some results.

{
  "style": Style,
  "clazz": "java.lang.String",
  "fieldNames": [ "column1", "column2", ... ]
}

style A string denoting the Style of the contained objects.

DatabaseProperty

This object represents the exposed database properties for a Connection through the Avatica server.

One of:

GET_STRING_FUNCTIONS
GET_NUMERIC_FUNCTIONS
GET_SYSTEM_FUNCTIONS
GET_TIME_DATE_FUNCTIONS
GET_S_Q_L_KEYWORDS
GET_DEFAULT_TRANSACTION_ISOLATION

Frame

This object represents a batch of results, tracking the offset into the results and whether more results still exist to be fetched in the Avatica server.

{
  "offset": 100,
  "done": true,
  "rows": [ [ val1, val2, ... ], ... ]
}

offset The starting position of these rows in the encompassing result set.

done A boolean denoting whether more results exist for this result set.

rows An array of arrays corresponding to the rows and columns for the result set.

QueryState

This object represents the way a ResultSet was created in the Avatica server. A ResultSet could be created by a user-provided SQL or by a DatabaseMetaData operation with arguments on that operation.

{
  "type": StateType,
  "sql": "SELECT * FROM table",
  "metaDataOperation": MetaDataOperation,
  "operationArgs": ["arg0", "arg1", ... ]
}

type A StateType object denoting what type of operation backs the ResultSet for this query.

sql The SQL statement which created the ResultSet for this query. Required if the type is SQL.

metaDataOperation The DML operation which created the ResultSet for this query. Required if the type is METADATA.

operationArgs The arguments to the invoked DML operation. Required if the type is METADATA.

Rep

This enumeration represents the concrete Java type for some value.

One of:

PRIMITIVE_BOOLEAN
PRIMITIVE_BYTE
PRIMITIVE_CHAR
PRIMITIVE_SHORT
PRIMITIVE_INT
PRIMITIVE_LONG
PRIMITIVE_FLOAT
PRIMITIVE_DOUBLE
BOOLEAN
BYTE
CHARACTER
SHORT
INTEGER
LONG
FLOAT
DOUBLE
JAVA_SQL_TIME
JAVA_SQL_TIMESTAMP
JAVA_SQL_DATE
JAVA_UTIL_DATE
BYTE_STRING
STRING
NUMBER
OBJECT

RpcMetadata

This object contains assorted per-call/contextual metadata returned by the Avatica server.

{
  "serverAddress": "localhost:8765"
}

serverAddress The host:port of the server which created this object.

Signature

This object represents the result of preparing a Statement in the Avatica server.

{
  "columns": [ ColumnMetaData, ColumnMetaData, ... ],
  "sql": "SELECT * FROM table",
  "parameters": [ AvaticaParameter, AvaticaParameter, ... ],
  "cursorFactory": CursorFactory,
  "statementType": StatementType
}

columns An array of ColumnMetaData objects denoting the schema of the result set.

sql The SQL executed.

parameters An array of AvaticaParameter objects denoting type-specific details.

cursorFactory An CursorFactory object representing the Java representation of the frame.

statementType An StatementType object representing the type of Statement.

StateType

This enumeration denotes whether user-provided SQL or a DatabaseMetaData operation was used to create some ResultSet.

One of:

SQL
METADATA

StatementHandle

This object encapsulates all of the information of a Statement created in the Avatica server.

{
  "connectionId": "000000-0000-0000-00000000",
  "id": 12345,
  "signature": Signature
}

connectionId The identifier of the connection to which this statement belongs.

id The identifier of the statement.

signature A Signature object for the statement.

StatementType

This enumeration represents what kind the Statement is.

One of:

SELECT
INSERT
UPDATE
DELETE
UPSERT
MERGE
OTHER_DML
CREATE
DROP
ALTER
OTHER_DDL
CALL

Style

This enumeration represents the generic “class” of type for a value.

One of:

OBJECT
RECORD
RECORD_PROJECTION
ARRAY
LIST
MAP

TypedValue

This object encapsulates the type and value for a column in a row.

{
  "type": "type_name",
  "value": object
}

type A name referring to the type of the object stored in value.

value A JSON representation of a JDBC type.

The following chart documents how each Rep value is serialized into a JSON value. Consult the JSON documentation for more information on valid attributes in JSON.

Rep Value	Serialized	Description
PRIMITIVE_BOOLEAN	boolean
BOOLEAN	boolean
PRIMITIVE_BYTE	number	The numeric value of the `byte`.
BYTE	number
PRIMITIVE_CHAR	string
CHARACTER	string
PRIMITIVE_SHORT	number
SHORT	number
PRIMITIVE_INT	number
INTEGER	number
PRIMITIVE_LONG	number
LONG	number
PRIMITIVE_FLOAT	number
FLOAT	number
PRIMITIVE_DOUBLE	number
DOUBLE	number
BIG_INTEGER	number	Implicitly handled by Jackson.
BIG_DECIMAL	number	Implicitly handled by Jackson.
JAVA_SQL_TIME	number	As an integer, milliseconds since midnight.
JAVA_SQL_DATE	number	As an integer, the number of days since the epoch.
JAVA_SQL_TIMESTAMP	number	As a long, milliseconds since the epoch.
JAVA_UTIL_DATE	number	As a long, milliseconds since the epoch.
BYTE_STRING	string	A Base64-encoded string.
STRING	string
NUMBER	number	A general number, unknown what concrete type.
OBJECT	null	Implicitly converted by Jackson.
NULL	null	Implicitly converted by Jackson.
ARRAY	N/A	Implicitly handled by Jackson.
STRUCT	N/A	Implicitly handled by Jackson.
MULTISET	N/A	Implicitly handled by Jackson.