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Oracle® Database PL/SQL Packages and Types Reference
11g Release 1 (11.1)

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147 DBMS_XA

The DBMS_XA package contains the XA/Open interface for applications to call XA interface in PL/SQL. Using this package, application developers can switch or share transactions across SQL*Plus sessions or processes using PL/SQL.

See Also:

Oracle Database Advanced Application Developer's Guide for more information about "Developing Applications with Oracle XA"

The chapter contains the following topics:


Using DBMS_XA


Overview

These subprograms allow a PL/SQL application to define a global transaction branch ID (XID) and associate or disassociate the current session with the transaction branch.

Subsequently, these transaction branches may be prepared and committed by following the two-phase commit protocol. A single-phase commit protocol is also supported if only one resource manager is involved.

Interfaces are also provided for a PL/SQL application to set the timeout values for any new global transaction branches that may start with the current session.


Security Model

This package is created under SYS. Operations provided by this package are performed under the current calling user, not under the package owner SYS.Any DBMS_XA subprogram called from an anonymous PL/SQL block is executed using the privileges of the current user. Any DBMS_XA subprogram called from a stored procedure is executed using the privileges of the owner of the stored procedure.

SELECT privilege on SYS.DBA_PENDING_TRANSACTIONS is required for users who need to execute XA_RECOVER subprogram.

FORCE ANY TRANSACTION privilege is required for users who need to manipulate XA transactions created by other users.


Constants

The DBMS_XA package uses the constants shown in Table 147-1 for use in the flag field of the XA_START Function and the XA_END Function.

Table 147-1 DBMS_XA Constants for Flag Field of XA_START & XA_END Functions

Name Type Value Description

TMNOFLAGS

PLS_INTEGER

00000000

Indicates no flag value is selected.

TMSUCCESS

PLS_INTEGER

UTL_RAW.CAST_TO_BINARY_INTEGER ('04000000')

Dissociates caller from transaction branch

TMJOIN

PLS_INTEGER

UTL_RAW.CAST_TO_BINARY_INTEGER ('00200000')

Caller is joining existing transaction branch.

TMSUSPEND

PLS_INTEGER

UTL_RAW.CAST_TO_BINARY_INTEGER ('02000000')

Caller is suspending, not ending, association

TMRESUME

PLS_INTEGER

UTL_RAW.CAST_TO_BINARY_INTEGER ('08000000')

Caller is resuming association with suspended transaction branch.


The DBMS_XA package uses the constants shown in Table 147-2 for Possible Return Values

Table 147-2 DBMS_XA Constants for Possible Return Values

Name Type Value Description

XA_RBBASE

PLS_INTEGER

100

Inclusive lower bound of the rollback codes

XA_RBROLLBACK

PLS_INTEGER

XA_RBBASE

Rollback was caused by an unspecified reason

XA_RBCOMMFAIL

PLS_INTEGER

XA_RBBASE+1

Rollback was caused by a communication failure

XA_RBDEADLOCK

PLS_INTEGER

XA_RBBASE+2

Deadlock was detected

XA_RBINTEGRITY

PLS_INTEGER

XA_RBBASE+3

Condition that violates the integrity of the resources was detected

XA_RBOTHER

PLS_INTEGER

XA_RBBASE+4

Resource manager rolled back the transaction for an unlisted reason

XA_RBPROTO

PLS_INTEGER

XA_RBBASE+5

Protocol error occurred in the resource manager

XA_RBTIMEOUT

PLS_INTEGER

XA_RBBASE+6

transaction branch took long

XA_RBTRANSIENT

PLS_INTEGER

XA_RBBASE+7

May retry the transaction branch

XA_RBEND

PLS_INTEGER

XA_RBTRANSIENT

Inclusive upper bound of the rollback codes

XA_NOMIGRATE

PLS_INTEGER

9

Transaction branch may have been heuristically completed

XA_HEURHAZ

PLS_INTEGER

8

Transaction branch may have been heuristically completed

XA_HEURCOM

PLS_INTEGER

7

Transaction branch has been heuristically committed

XA_HEURRB

PLS_INTEGER

6

Transaction branch has been heuristically rolled back

XA_HEURMIX

PLS_INTEGER

5

Some of the transaction branches have been heuristically committed, others rolled back

XA_RETRY

PLS_INTEGER

4

Routine returned with no effect and may be re-issued

XA_RDONLY

PLS_INTEGER

3

Transaction was read-only and has been committed

XA_OK

PLS_INTEGER

0

Normal execution

XAER_ASYNC

PLS_INTEGER

-2

Asynchronous operation already outstanding

XAER_RMERR

PLS_INTEGER

-3

Resource manager error occurred in the transaction branch

XAER_NOTA

PLS_INTEGER

-4

XID is not valid

XAER_INVAL

PLS_INTEGER

-5

Invalid arguments were given

XAER_PROTO

PLS_INTEGER

-6

Routine invoked in an improper context

XAER_RMFAIL

PLS_INTEGER

-7

Resource manager unavailable

XAER_DUPID

PLS_INTEGER

-8

XID already exists

XAER_OUTSIDE

PLS_INTEGER

-9

Resource manager doing work outside global transaction



Operational Notes

In compliance with the XA specification of the X/Open CAE Standard for Distributed Transaction Processing, XA_PREPARE/COMMIT/ ROLLBACK/FORGET may not be called when the transaction is still associated with the current session. Only after XA_END has been called so that there is not any transaction associated with the current session, the application may call XA_PREPARE/COMMIT/ ROLLBACK/FORGET.

XAER_PROTO error is returned from XA_PREPARE/COMMIT/ROLLBACK/FORGET if a transaction is being associated with the current session.

Prior to calling any of the package subprograms, a connection/session must have already been established to the Oracle database server backend, or a resource manager. Resource manager identifiers are not supported. If multiple resource managers are involved, multiple connections/sessions must be pre-established to each resource manager before calling any the package subprograms. If multiple connections/sessions are established during the course of global transaction processing, the caller must ensure that all of those connections/sessions associated with a specific global transaction branch identifier (XID) are established to the same resource manager.


Data Structures

The DBMS_XA package uses the following OBJECT type and associated TABLE type.

OBJECT Types

TABLE Types


DBMS_XA_XID Object Type

The PL/SQL XA interface allows the PL/SQL application to define a global transaction branch id (XID) and associate/disassociate the current session with the transaction branch. XID is defined as a PL/SQL object type.

See Also:

For more information, see "Distributed Transaction Processing: The XA Specification" in the public XA Standard.

Syntax

TYPE DBMS_XA_XID IS OBJECT(
  formatid      NUMBER,
  gtrid         RAW(64),
  bqual         RAW(64),
  constructor function DBMS_XA_XID(
       gtrid     IN   NUMBER)
    RETURN SELF AS RESULT,
  constructor function DBMS_XA_XID (
       gtrid     IN   RAW, 
       bqual     IN   RAW)
    RETURN SELF AS RESULT,
  constructor function DBMS_XA_XID(
       formatid  IN   NUMBER,
       gtrid     IN   RAW,
       bqual     IN   RAW DEFAULT HEXTORAW('00000000000000000000000000000001'))
    RETURN SELF AS RESULT)

Attributes

Table 147-3 DBMS_XA_XID Object Type

Attribute Description

formatid

Format identifier, a number identifying different transaction managers (TM)

gtrid

Global transaction identifier uniquely identifying a global transaction, of which the maximum size is 64 bytes

bqual

Branch qualifier, of which the maximum size is 64 bytes



DBMS_XA_XID_ARRAY Table Type

This type is used to define an array of xid that represent a list of global transaction branches.

Syntax

TYPE DBMS_XA_XID_ARRAY as TABLE of DBMS_XA_XID

Summary of DBMS_XA Subprograms

Table 147-4 DBMS_APPLICATION_INFO Package Subprograms

Subprogram Description

DIST_TXN_SYNC Procedure

Used in recovery of synchronization when utilizing Oracle Real Application Clusters (RAC)

XA_COMMIT Function

Commits the global transaction specified by xid

XA_END Function

Disassociates the current session from the transaction branch specified by xid

XA_FORGET Function

Informs the resource manager to forget about a heuristically committed or rolled back transaction branch.

XA_GETLASTOER Function

Obtains the last Oracle error code, in case of failure of previous XA calls.

XA_PREPARE Function

Prepares the transaction branch specified in xid for committing the transaction subsequently if possible

XA_RECOVER Function

Obtains a list of prepared or heuristically completed transaction branches from a resource manager

XA_ROLLBACK Function

Informs the resource manager to roll back work done on behalf of a transaction branch

XA_SETTIMEOUT Function

Sets the transaction timeout in seconds for the current session

XA_START Function

Associates the current session with the transaction branch specified by xid



DIST_TXN_SYNC Procedure

This procedure can be used to synchronize in-doubt transactions when one of the Oracle Real Application Clusters (RAC) instances fails.

Syntax

DBMS_XA.DIST_TXN_SYNC; 

XA_COMMIT Function

This function commits the global transaction specified by xid.

Syntax

DBMS_XA.XA_COMMIT (
   xid       IN  DBMS_XA_XID,
   onePhase  IN  BOOLEAN)
RETURN PLS_INTEGER;

Parameters

Table 147-5 XA_COMMIT Function Parameters

Parameter Description

xid

See DBMS_XA_XID Object Type

onePhase

If TRUE, apply single phase commit


Return Values

See Table 147-2, "DBMS_XA Constants for Possible Return Values". Possible return values indicating error are: XAER_RMERR, XAER_RMFAIL, XAER_NOTA, XAER_INVAL, or XAER_PROTO. Other possible return values include: XA_OK, XA_RB*, XA_HEURHAZ, XA_HEURCOM, XA_HEURRB, and XA_HEURMIX.

Usage Notes


XA_END Function

This function disassociates the current session from the transaction branch specified by xid

A transaction manager calls XA_END when a thread of control finishes, or needs to suspend work on, a transaction branch. This occurs when the application completes a portion of its work, either partially or in its entirety (for example, before blocking on some event in order to let other threads of control work on the branch). When XA_END successfully returns, the calling thread of control is no longer actively associated with the branch but the branch still exists

Syntax

DBMS_XA.XA_END (
   xid   IN  DBMS_XA_XID,
   flag  IN  PLS_INTEGER)
RETURN PLS_INTEGER;

Parameters

Table 147-6 XA_END Function Parameters

Parameter Description

xid

See DBMS_XA_XID Object Type

flag

See Table 147-1, "DBMS_XA Constants for Flag Field of XA_START & XA_END Functions".


Return Values

See Table 147-2, "DBMS_XA Constants for Possible Return Values". Possible return values in error are XAER_RMERR, XAER_RMFAILED, XAER_NOTA, XAER_INVAL, XAER_PROTO, or XA_RB*.

Usage Notes


XA_FORGET Function

This function informs the resource manager to forget about a heuristically committed or rolled back transaction branch.

Syntax

DBMS_XA.XA_FORGET (
   xid       IN  DBMS_XA_XID)
RETURN PLS_INTEGER;

Parameters

Table 147-7 XA_FORGET Function Parameters

Parameter Description

xid

See DBMS_XA_XID Object Type


Return Values

See Table 147-2, "DBMS_XA Constants for Possible Return Values". Possible return values are XA_OK, XAER_RMERR, XAER_RMFAIL, XAER_NOTA, XAER_INVAL, or XAER_PROTO.


XA_GETLASTOER Function

This function obtains the last Oracle error code, in case of failure of previous XA calls.

Syntax

DBMS_XA.XA_GETLASTOER  
 RETURN PLS_INTEGER;

Return Values

The return value carries the last Oracle error code.


XA_PREPARE Function

This function prepares the transaction branch specified in xid for committing the transaction subsequently if possible.

Syntax

DBMS_XA.XA_PREPARE (
   xid   IN  DBMS_XA_XID)
RETURN PLS_INTEGER;

Parameters

Table 147-8 XA_PREPARE Function Parameters

Parameter Description

xid

See DBMS_XA_XID Object Type


Return Values

See Table 147-2, "DBMS_XA Constants for Possible Return Values". Possible return codes include: XA_OK, XA_RDONLY, XA_RB*, XAER_RMERR, XAER_RMFAIL, XAER_NOTA, XAER_INVAL, or XAER_PROTO.

Usage Notes


XA_RECOVER Function

This function obtains a list of prepared or heuristically completed transaction branches from a resource manager.

Syntax

DBMS_XA.XA_RECOVER 
 RETURN DBMS_XA_XID_ARRAY;

Return Values

See DBMS_XA_XID_ARRAY Table Type

Usage Notes


XA_ROLLBACK Function

This function informs the resource manager to roll back work done on behalf of a transaction branch.

Syntax

DBMS_XA.XA_ROLLBACK (
   xid       IN  DBMS_XA_XID)
 RETURN PLS_INTEGER;

Parameters

Table 147-9 XA_ROLLBACK Function Parameters

Parameter Description

xid

See DBMS_XA_XID Object Type


Return Values

See Table 147-2, "DBMS_XA Constants for Possible Return Values". Possible return values are: XA_OK, XA_RB*, XA_HEURHAZ, XA_HEURCOM, XA_HEURRB, or XA_HEURMIX.

Usage Notes

If a user needs to rollback a transaction branch that created by other users, the privilege FORCE ANY TRANSACTION must be granted to the user.


XA_SETTIMEOUT Function

This function sets the transaction timeout in seconds for the current session.

Syntax

DBMS_XA.XA_SETTIMEOUT (
   seconds  IN  PLS_INTEGER)
RETURN PLS_INTEGER;

Parameters

Table 147-10 XA_SETTIMEOUT Function Parameters

Parameter Description

seconds

The timeout value indicates the maximum time in seconds that a transaction branch may be disassociated from the session before the system automatically aborts the transaction. The default value is 60 seconds.


Return Values

See Table 147-2, "DBMS_XA Constants for Possible Return Values". Possible return values are XA_OK, XAER_RMERR, XAER_RMFAIL, or XAER_INVAL.

Usage Notes

Only if return value is XA_OK, is the timeout value successfully set.


XA_START Function

This function associates the current session with a transaction branch specified by the xid.

Syntax

DBMS_XA.XA_START (
   xid   IN  DBMS_XA_XID,    flag  IN  PLS_INTEGER)  RETURN PLS_INTEGER;

Parameters

Table 147-11 XA_START Function Parameters

Parameter Description

xid

See DBMS_XA_XID Object Type

flag

See Table 147-1, "DBMS_XA Constants for Flag Field of XA_START & XA_END Functions".


Return Values

See Table 147-2, "DBMS_XA Constants for Possible Return Values"

Usage Notes