The XA interface defines the contract between a Resource Manager and a Transaction Manager in a distributed transaction processing (DTP) environment. A JDBC driver or a JMS provider implements this interface to support the association between a global transaction and a database or message service connection.
The XAResource interface can be supported by any transactional
resource that is intended to be used by application programs in an
environment where transactions are controlled by an external
transaction manager. An example of such a resource is a database
management system. An application may access data through multiple
database connections. Each database connection is enlisted with
the transaction manager as a transactional resource. The transaction
manager obtains an XAResource for each connection participating
in a global transaction. The transaction manager uses the
start method
to associate the global transaction with the resource, and it uses the
end method to disassociate the transaction from
the resource. The resource
manager is responsible for associating the global transaction to all
work performed on its data between the start and end method invocations.
At transaction commit time, the resource managers are informed by the transaction manager to prepare, commit, or rollback a transaction according to the two-phase commit protocol.
- Since:
- 1.4
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final intEnds a recovery scan.static final intDisassociates the caller and marks the transaction branch rollback-only.static final intCaller is joining existing transaction branch.static final intUse TMNOFLAGS to indicate no flags value is selected.static final intCaller is using one-phase optimization.static final intCaller is resuming association with a suspended transaction branch.static final intStarts a recovery scan.static final intDisassociates caller from a transaction branch.static final intCaller is suspending (not ending) its association with a transaction branch.static final intThe transaction work has been prepared normally.static final intThe transaction branch has been read-only and has been committed. -
Method Summary
Modifier and TypeMethodDescriptionvoidCommits the global transaction specified by xid.voidEnds the work performed on behalf of a transaction branch.voidTells the resource manager to forget about a heuristically completed transaction branch.intObtains the current transaction timeout value set for this XAResource instance.booleanisSameRM(XAResource xares) This method is called to determine if the resource manager instance represented by the target object is the same as the resouce manager instance represented by the parameter xares.intAsk the resource manager to prepare for a transaction commit of the transaction specified in xid.Xid[]recover(int flag) Obtains a list of prepared transaction branches from a resource manager.voidInforms the resource manager to roll back work done on behalf of a transaction branch.booleansetTransactionTimeout(int seconds) Sets the current transaction timeout value for thisXAResourceinstance.voidStarts work on behalf of a transaction branch specified inxid.
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Field Details
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TMENDRSCAN
static final int TMENDRSCANEnds a recovery scan.- See Also:
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TMFAIL
static final int TMFAILDisassociates the caller and marks the transaction branch rollback-only.- See Also:
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TMJOIN
static final int TMJOINCaller is joining existing transaction branch.- See Also:
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TMNOFLAGS
static final int TMNOFLAGSUse TMNOFLAGS to indicate no flags value is selected.- See Also:
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TMONEPHASE
static final int TMONEPHASECaller is using one-phase optimization.- See Also:
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TMRESUME
static final int TMRESUMECaller is resuming association with a suspended transaction branch.- See Also:
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TMSTARTRSCAN
static final int TMSTARTRSCANStarts a recovery scan.- See Also:
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TMSUCCESS
static final int TMSUCCESSDisassociates caller from a transaction branch.- See Also:
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TMSUSPEND
static final int TMSUSPENDCaller is suspending (not ending) its association with a transaction branch.- See Also:
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XA_RDONLY
static final int XA_RDONLYThe transaction branch has been read-only and has been committed.- See Also:
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XA_OK
static final int XA_OKThe transaction work has been prepared normally.- See Also:
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Method Details
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commit
Commits the global transaction specified by xid.- Parameters:
xid- A global transaction identifieronePhase- If true, the resource manager should use a one-phase commit protocol to commit the work done on behalf of xid.- Throws:
XAException- An error has occurred. Possible XAExceptions are XA_HEURHAZ, XA_HEURCOM, XA_HEURRB, XA_HEURMIX, XAER_RMERR, XAER_RMFAIL, XAER_NOTA, XAER_INVAL, or XAER_PROTO.If the resource manager did not commit the transaction and the paramether onePhase is set to true, the resource manager may throw one of the XA_RB* exceptions. Upon return, the resource manager has rolled back the branch's work and has released all held resources.
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end
Ends the work performed on behalf of a transaction branch. The resource manager disassociates the XA resource from the transaction branch specified and lets the transaction complete.If TMSUSPEND is specified in the flags, the transaction branch is temporarily suspended in an incomplete state. The transaction context is in a suspended state and must be resumed via the
startmethod with TMRESUME specified.If TMFAIL is specified, the portion of work has failed. The resource manager may mark the transaction as rollback-only
If TMSUCCESS is specified, the portion of work has completed successfully.
- Parameters:
xid- A global transaction identifier that is the same as the identifier used previously in thestartmethod.flags- One of TMSUCCESS, TMFAIL, or TMSUSPEND.- Throws:
XAException- An error has occurred. Possible XAException values are XAER_RMERR, XAER_RMFAILED, XAER_NOTA, XAER_INVAL, XAER_PROTO, or XA_RB*.
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forget
Tells the resource manager to forget about a heuristically completed transaction branch.- Parameters:
xid- A global transaction identifier.- Throws:
XAException- An error has occurred. Possible exception values are XAER_RMERR, XAER_RMFAIL, XAER_NOTA, XAER_INVAL, or XAER_PROTO.
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getTransactionTimeout
Obtains the current transaction timeout value set for this XAResource instance. IfXAResource.setTransactionTimeoutwas not used prior to invoking this method, the return value is the default timeout set for the resource manager; otherwise, the value used in the previoussetTransactionTimeoutcall is returned.- Returns:
- the transaction timeout value in seconds.
- Throws:
XAException- An error has occurred. Possible exception values are XAER_RMERR and XAER_RMFAIL.
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isSameRM
This method is called to determine if the resource manager instance represented by the target object is the same as the resouce manager instance represented by the parameter xares.- Parameters:
xares- An XAResource object whose resource manager instance is to be compared with the resource manager instance of the target object.- Returns:
- true if it's the same RM instance; otherwise false.
- Throws:
XAException- An error has occurred. Possible exception values are XAER_RMERR and XAER_RMFAIL.
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prepare
Ask the resource manager to prepare for a transaction commit of the transaction specified in xid.- Parameters:
xid- A global transaction identifier.- Returns:
- A value indicating the resource manager's vote on the outcome of the transaction. The possible values are: XA_RDONLY or XA_OK. If the resource manager wants to roll back the transaction, it should do so by raising an appropriate XAException in the prepare method.
- Throws:
XAException- An error has occurred. Possible exception values are: XA_RB*, XAER_RMERR, XAER_RMFAIL, XAER_NOTA, XAER_INVAL, or XAER_PROTO.
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recover
Obtains a list of prepared transaction branches from a resource manager. The transaction manager calls this method during recovery to obtain the list of transaction branches that are currently in prepared or heuristically completed states.- Parameters:
flag- One of TMSTARTRSCAN, TMENDRSCAN, TMNOFLAGS. TMNOFLAGS must be used when no other flags are set in the parameter.- Returns:
- The resource manager returns zero or more XIDs of the transaction branches that are currently in a prepared or heuristically completed state. If an error occurs during the operation, the resource manager should throw the appropriate XAException.
- Throws:
XAException- An error has occurred. Possible values are XAER_RMERR, XAER_RMFAIL, XAER_INVAL, and XAER_PROTO.
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rollback
Informs the resource manager to roll back work done on behalf of a transaction branch.- Parameters:
xid- A global transaction identifier.- Throws:
XAException- An error has occurred.
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setTransactionTimeout
Sets the current transaction timeout value for thisXAResourceinstance. Once set, this timeout value is effective untilsetTransactionTimeoutis invoked again with a different value. To reset the timeout value to the default value used by the resource manager, set the value to zero. If the timeout operation is performed successfully, the method returns true; otherwise false. If a resource manager does not support explicitly setting the transaction timeout value, this method returns false.- Parameters:
seconds- The transaction timeout value in seconds.- Returns:
- true if the transaction timeout value is set successfully; otherwise false.
- Throws:
XAException- An error has occurred. Possible exception values are XAER_RMERR, XAER_RMFAIL, or XAER_INVAL.
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start
Starts work on behalf of a transaction branch specified inxid. If TMJOIN is specified, the start applies to joining a transaction previously seen by the resource manager. If TMRESUME is specified, the start applies to resuming a suspended transaction specified in the parameterxid. If neither TMJOIN nor TMRESUME is specified and the transaction specified byxidhas previously been seen by the resource manager, the resource manager throws the XAException exception with XAER_DUPID error code.- Parameters:
xid- A global transaction identifier to be associated with the resource.flags- One of TMNOFLAGS, TMJOIN, or TMRESUME.- Throws:
XAException- An error has occurred. Possible exceptions are XA_RB*, XAER_RMERR, XAER_RMFAIL, XAER_DUPID, XAER_OUTSIDE, XAER_NOTA, XAER_INVAL, or XAER_PROTO.
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