Firebird Documentation Index → Firebird Wire Protocol

1. Introduction

This document describes the Firebird wire protocol. Most of the information was obtained by studying the Firebird source code and implementing the wire protocol in the Firebird .NET provider and Jaybird (Firebird JDBC driver).

The protocol is described in the form of the message sent by the client and received from the server. The described protocol is Firebird/Interbase protocol version 10. Earlier (Interbase) versions of the protocol are not in scope for this document. Changes in later protocol versions are described in notes below the description of the relevant version 10 message (currently only version 11 is partially described).

This document is not complete. It is advisable to consult the Interbase 6.0 API Guide for additional information on subjects like parsing the status vector, information request items, and the meaning of operations.

Unless otherwise indicated, a client request must be flushed to the server for processing. For some operations the flush can be deferred, so it is sent together with a different operation. Versions 11 and higher of the wire protocol explicitly support (or even require) deferring of operations, including deferring the read of the response.

2. Responses

The wire protocol has a limited set of responses. Some operations have a specific response, which is described together with the operation. Most operation however use one (or more) of the responses described in this section. The meaning and content depend on the operation that initiated the response.

2.1. Generic response

Int32

Operation code

If operation equals op_response:

Int32

Object handle

Int64

Object ID

Buffer

Data (meaning depends on the operation).

Byte[]

Status vector

Information about parsing the status vector can be found in the Interbase 6.0 API Guide in the documentation set. It might also be advantageous to look at the sources of the Firebird .NET provider or Jaybird.

2.2. SQL response

Int32

Operation code

If operation equals op_sql_response:

Int32

Message count

Buffer

Response data (meaning depends on the operation).

2.3. Fetch response

Int32

Operation code

If operation equals op_fetch_response:

Int32

Status

A value of 0 is the success value.

End of cursor is indicated with a non-zero status.

A status with value of 100 means that there are no more rows.

Int32

Count of rows following response

The data rows are not in a buffer as described in Data types, but as a sequence of data rows, see Reading row data.

2.4. Slice response

Int32

Operation code

If operation equals op_slice:

Int32

Slice length

Int32

Slice length

Buffer

Slice data

3. Databases

3.1. Attach

Attachments to a database are done in two steps, first identification (connect) to the server, then attachment to a database.

3.1.1. Identification

Performs the initial handshake and protocol selection.

Client
Int32

Operation code (op_connect)

Int32

Operation code (op_attach)

Int32

Version (CONNECT_VERSION2)

Int32

Architecture type (eg arch_generic = 1).

String

Database path or alias

Int32

Count of protocol versions understood (eg 1)

Buffer

User identification

The next block of data declares the protocol(s) that the client is willing or able to support. It should be sent as many times as protocols are supported (and specified as Count of protocol versions understood), values depend on the protocol.

Int32

Protocol version (PROTOCOL_VERSION10)

Int32

Architecture type (eg arch_generic = 1)

Int32

Minimum type (eg ptype_rpc = 2)

Int32

Maximum type (eg ptype_batch_send = 3)

Int32

Preference weight (eg 2)

Server
Int32

Operation code

If operation equals op_accept:

Int32

Protocol version number accepted by server

Int32

Architecture for protocol

Int32

Minumum type

3.1.2. Attachment

Attaches to a database.

Client
Int32

Operation code (op_attach)

Int32

Database object id (0)

String

Database path or alias

Buffer

Database parameter buffer

Table 1. Example of parameters sent in the DPB
Parameter Description Value Optional

isc_dpb_version1

Version (must be first item!)

 

 

isc_dpb_dummy_packet_interval

Dummy packet interval

120

*

isc_dpb_sql_dialect

SQL dialect

3

 

isc_dpb_lc_ctype

Character set

UTF8

 

isc_dpb_sql_role_name

User role

RDB$ADMIN

*

isc_dpb_connect_timeout

Connection timeout

10

*

isc_dpb_user_name

User name

SYSDBA

 

isc_dpb_password

User password

masterkey

 

Server

Generic response — where the Object handle is the database handle.

3.2. Detach

Detaches from the database. After detach the connection is still open, to disconnect use Disconnect (op_disconnect).

Client
Int32

Operation code (op_detach)

Int32

Database handle

Server

3.3. Create

Create a database. Create is similar to Attachment (op_attach).

Client
Int32

Operation code (op_create)

Int32

Database object id (0)

String

Database path

Buffer

Database parameter buffer

Server

Generic response — where the Object handle is the database handle.

3.4. Drop

Drops the currently attached database.

Client
Int32

Operation code (op_drop_database)

Int32

Database handle

Server

3.5. Database information request

Requests database or server information.

Client
Int32

Operation code (op_info_database)

Int32

Database handle

Int32

Incarnation of object (0)

Buffer

Requested information items

Int32

Length of buffer available for receiving response (too small may lead to receiving a truncated buffer, which necessitates requesting information again).

The buffer in the response is sized to the actual length of the response (upto the declared available length), so specifying a larger than necessary size does not inflate the response on the wire.

Server

Generic response — where Data holds the requested information.

3.6. Disconnect

Client

Int32

Operation code (op_disconnect)

No response, remote socket close.

4. Transactions

4.1. Start transaction

Starts a transaction with the transaction options specified in the transaction parameter buffer.

Client
Int32

Operation code (op_transaction)

Int32

Database handle

Buffer

Transaction parameter buffer

Server

Generic response — where Object handle is the new transaction handle.

4.2. Commit transaction

Commits an active or prepared transaction.

Client
Int32

Operation code (op_commit)

Int32

Transaction handle

Server

4.3. Rollback transaction

Rolls back an active or prepared transaction.

Client
Int32

Operation code (op_rollback)

Int32

Transaction handle

Server

4.4. Commit retaining

Commits an active or prepared transaction, retaining the transaction context.

Client
Int32

Operation code (op_commit_retaining)

Int32

Transaction handle

Server

4.5. Rollback retaining

Rolls back an active or prepared transaction, retaining the transaction context.

Client
Int32

Operation code (op_rollback_retaining)

Int32

Transaction handle

Server

4.6. Prepare

Performs the first stage of a two-phase commit. After prepare a transaction is in-limbo until committed or rolled back.

4.6.1. Simple prepare

Client
Int32

Operation code (op_prepare)

Int32

Transaction handle

Server

4.6.2. Prepare with message

Associates a message (byte data) with the prepared transaction. This information is stored in RDB$TRANSACTIONS and can be used for recovery purposes.

Client
Int32

Operation code (op_prepare2)

Int32

Transaction handle

Buffer

Recovery information

Server

4.7. Transaction information request

This is similar to Database information request.

Client
Int32

Operation code (op_transaction_info)

Int32

Database handle

Int32

Incarnation of object (0)

Buffer

Requested information items

Int32

Length of buffer available for receiving response (too small may lead to receiving truncated buffer).

Generic response — where Data holds the requested information.

5. Statements

5.1. Allocate

Allocates a statement handle on the server.

Client
Int32

Operation code (op_allocate_statement)

Int32

Database handle

Server

Generic response — where Object handle is the allocated statement handle.

5.1.1. Deviations for protocol version 11

An allocate can only be sent together with a Prepare operation.

5.2. Free

Frees resources held by the statement.

Client
Int32

Operation code (op_free_statement)

Int32

Statement handle

Int32

Option Description

DSQL_close

Closes the cursor opened after statement execute.

DSQL_drop

Releases the statement handle.

Server

5.2.1. Deviations for protocol version 11

Request flushing and response processing must be deferred.

5.3. Prepare

Client
Int32

Operation code (op_prepare_statement)

Int32

Transaction handle

Int32

Statement handle

Int32

SQL dialect

String

Statement to be prepared

Buffer

Describe and describe bind information items

Example of requested information items
  • isc_info_sql_select

  • isc_info_sql_describe_vars

  • isc_info_sql_sqlda_seq

  • isc_info_sql_type

  • isc_info_sql_sub_type

  • isc_info_sql_length

  • isc_info_sql_scale

  • isc_info_sql_field

  • isc_info_sql_relation

Int32

Target buffer length (32768)

Server

Generic response — where Data holds the statement description (matching the requested information items)

5.3.1. Deviations for protocol version 11

The statement handle can no longer be allocated separately. The initial Allocate operation must be sent together with the first prepare operation. When allocating and preparing together, the value of the statement handle of the prepare must be 0xFFFF (invalid object handle). The responses must be processed in order: first allocate response, then prepare response.

Once a statement handle has been allocated, it can be reused by sending a prepare with the obtained statement handle.

5.4. Describe

Describe of output parameters of a query is done using the statements information request message

Example of requested information items :
  • isc_info_sql_select

  • isc_info_sql_describe_vars

  • isc_info_sql_sqlda_seq

  • isc_info_sql_type

  • isc_info_sql_sub_type

  • isc_info_sql_length

  • isc_info_sql_scale

  • isc_info_sql_field

  • isc_info_sql_relation

5.5. Describe bind (input parameters)

Describe of input parameters of a query is done using the statements information request message

Example of requested information items :
  • isc_info_sql_select

  • isc_info_sql_describe_vars

  • isc_info_sql_sqlda_seq

  • isc_info_sql_type

  • isc_info_sql_sub_type

  • isc_info_sql_length

  • isc_info_sql_scale

  • isc_info_sql_field

  • isc_info_sql_relation

5.6. Execute

Client
Int32

Operation code

Operation Usage

op_execute

DDL and DML statements.

op_execute2

Stored procedures.

Int32

Statement handle

Int32

Transaction handle

If the statement has input parameters:

Buffer

Parameters in BLR format

Int32

Message number (0) ??

Int32

Number of messages (1) ??

Buffer

Parameter values

If not statement has no input parameters:

Buffer

Empty (length only 0)

Int32

Message number (0) ??

Int32

Number of messages (0) ??

If the statement is a stored procedure and there are output parameters:

Buffer

Output parameters in BLR format

Int32

Output message number (0) ??

Server
Int32

Operation code

If operation equals op_sql_response:

if not:

5.7. Rows affected by query execution

Obtain the rows affected by a query is done using the statements information request message

List of requested information items
  • isc_info_sql_records

5.8. Fetch

Client
Int32

Operation code (op_fetch)

Int32

Statement handle

Buffer

Output parameters in BLR format

Int32

Message number

Int32

Message count/Fetch size (200)

Server
Int32

Operation code

If operation equals op_fetch_response:

If not:

5.9. Set cursor name

Client
Int32

Operation code (op_set_cursor)

Int32

Statement handle

String

Cursor name (null terminated)

Int32

Cursor type (0).

Reserved for future use

Server

5.10. Information request

This is similar to Database information request.

Client
Int32

Operation code (op_info_sql)

Int32

Statement handle

Int32

Incarnation of object (0)

Buffer

Requested information items

Int32

Requested information items buffer length

Server

Generic response — where Data holds the requested information.

Information about how to parse the information buffer sent by the Firebird server can be found in the Interbase 6.0 documentation set

6. Blobs

6.1. Create/Open

Client
Int32

Operation code

Operation Description

op_create_blob

Creates a new blob

op_create_blob2

Creates a new blob with a blob parameter buffer

op_open_blob

Opens an existing blob

op_open_blob2

Opens an existing blob with a blob parameter buffer

Buffer

Blob parameter buffer (not allowed with op_create_blob and op_open_blob, required with op_create_blob2 and op_open_blob2)

Int32

Transaction handle

Int64

Blob ID

Server

Generic response — where:

  1. Object handle is the blob handle

  2. Object id is the blob id (only for op_create_blob / op_create_blob2, garbage for op_open_blob / op_open_blob2)

6.2. Get segment

Client
Int32

Operation code (op_get_segment)

Int32

Blob handle

Int32

Segment length (max length = 32768)

Int32

Data segment (0)

Server

Generic response — where Data is the blob segment.

6.3. Put segment

Client
Int32

Operation code (op_batch_segments)

Int32

Blob handle

Buffer

Blob Segments

Server

6.4. Seek

Client
Int32

Operation code (op_seek_blob)

Int32

Blob handle

Int32

Seek mode (0)

Int32

Offset

Server

Generic response — where Object handle is the current position.

6.5. Cancel

Cancels and invalidates the blob handle. If this was a newly created blob, the blob is disposed.

Client
Int32

Operation code (op_cancel_blob)

Int32

Blob handle

Server

Generic response — no useful information in response

6.5.1. Deviations for protocol version 11

Request flushing and response processing must be deferred.

6.6. Close

Closes and invalidates the blob handle.

Client
Int32

Operation code (op_close_blob)

Int32

Blob handle

Server

Generic response — no useful information in response

6.6.1. Deviations for protocol version 11

Request flushing and response processing must be deferred.

7. Arrays

7.1. Get slice

Client
Int32

Operation code (op_get_slice)

Int32

Transaction handle

Int64

Array handle

Int32

Slice length

Buffer

Slice descriptor (SDL)

String

Slice parameters (Always an empty string)

Buffer

Slice (Always empty)

Server

7.2. Put slice

Client
Int32

Operation code (op_put_slice)

Int32

transaction handle

Int64

Array handle (0)

Int32

Slice length

Buffer

Slice descriptor (SDL)

String

Slice parameters (Always an empty string)

Int32

Slice length

Buffer

Slice data

Server

Generic response — where Object id is the array handle.

8. Services

8.1. Attach

Client
Int32

Operation code (op_service_attach)

Int32

Database object ID (0)

String

Service name

For local connections: service_mgr

For remote connections: hostname:service_mgr

Buffer

Service parameter buffer

Server

Generic response — where Object handle is the services manager attachment handle.

8.2. Detach

Client
Int32

Operation code (op_service_detach)

Int32

Services manager attachment handle

Server

8.3. Start

Client
Int32

Operation code (op_service_start)

Int32

Services manager attachment handle

Int32

Incarnation of object (0)

Buffer

Services parameter buffer

Server

8.4. Query service

Client
Int32

Operation code (op_service_info)

Int32

Services manager attachment handle

Int32

Incarnation of object (0)

Buffer

Services parameter buffer

Buffer

Requested information items

Int32

Requested information items buffer length

Server

Generic response — where Data contains the requested information.

9. Events

9.1. Connection request

Client
Int32

Operation code (op_connect_request)

Int32

Connection type (P_REQ_async)

Int32

Partner identification (0)

Server
Int32

Attachment handle

Int16

Port number

This is part of the sockaddr_in structure.

It is not in XDR format

Int16

Socket family

This is part of the sockaddr_in structure.

It is not in XDR format

Byte[4]

IP Address

This is part of the sockaddr_in structure.

It is not in XDR format

Byte[8]

Zeroes

This is part of the sockaddr_in structure.

It is not in XDR format

Byte[4]

Garbage

9.2. Queue events

Client
Int32

Operation code (op_que_events)

Int32

Database handle

Buffer

Events parameter buffer

Int32

Ast function address

Int32

Ast parameters function address

Int32

Local event id

Server

Generic response — where Object handle holds the remote event id.

9.3. Cancel events

Client
Int32

Operation code (op_cancel_events)

Int32

Database handle

Int32

Local event id

Server

10. Reading row data

TODO: Processing row data

Appendix A: External Data Representation (XDR)

The Firebird wire protocol uses XDR for exchange messages between client and server.

Appendix B: Data types

Int32

Integer 32-bits

Int64

Integer 64-bits

Buffer

Type Description

Int32

Length

Byte[]

Buffer data

Byte[]

An array of bytes

String

A text string (Read/Written as a buffer)

Appendix C: Revision history

Revision History

0.1

31 May 2004

 

First draft for review.

0.2

02 Jun 2004

 

Fixed issues reported by Paul Vinkenoog.

0.3

03 Jun 2004

 

Added new subsections to the Statements section.

0.4

05 Jun 2004

 

Fixed issues reported by Paul Vinkenoog.

0.5

06 Jun 2004

 

Fixed issues reported by Paul Vinkenoog.

0.6

07 Jun 2004

 

Added events system documentation.

0.7

16 Jun 2004

 

Modifed document ID to wireprotocol.

0.8

17 Jun 2004

 

Added two new segmendted lists.

0.9

18 Jun 2004

 

  • Improved segmentedlist usage.

  • Fixed rendering of important tags.

0.10

19 Jun 2004

 

Changed rendering of important tags using Paul Vinkenoog fix.

0.11

20 Jun 2004

 

  • Added new segmentedlist.

  • Updated Statements.Prepare documentation.

  • Updated Statements.Execute documentation.

  • Updated Blobs.GetSegment documentation.

  • Updated Blobs.Seek documentation.

0.12

21 Jun 2004

 

Updated services information.

0.13

13 Sep 2014

 

Updated and expanded protocol information

0.14

04 Aug 2020

MR

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