javax.transaction.xa

Interface XAResource

public interface XAResource

The XAResource interface is a Java mapping of the industry standard XA interface based on the X/Open CAE Specification (Distributed Transaction Processing: The XA Specification).

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.

Field Summary

Fields

Modifier and Type	Field and Description
static int	TMENDRSCAN Ends a recovery scan.
static int	TMFAIL Disassociates the caller and marks the transaction branch rollback-only.
static int	TMJOIN Caller is joining existing transaction branch.
static int	TMNOFLAGS Use TMNOFLAGS to indicate no flags value is selected.
static int	TMONEPHASE Caller is using one-phase optimization.
static int	TMRESUME Caller is resuming association with a suspended transaction branch.
static int	TMSTARTRSCAN Starts a recovery scan.
static int	TMSUCCESS Disassociates caller from a transaction branch.
static int	TMSUSPEND Caller is suspending (not ending) its association with a transaction branch.
static int	XA_OK The transaction work has been prepared normally.
static int	XA_RDONLY The transaction branch has been read-only and has been committed.

Method Summary

Methods

Modifier and Type	Method and Description
void	commit(Xid xid, boolean onePhase) Commits the global transaction specified by xid.
void	end(Xid xid, int flags) Ends the work performed on behalf of a transaction branch.
void	forget(Xid xid) Tells the resource manager to forget about a heuristically completed transaction branch.
int	getTransactionTimeout() Obtains the current transaction timeout value set for this XAResource instance.
boolean	isSameRM(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.
int	prepare(Xid xid) Ask 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.
void	rollback(Xid xid) Informs the resource manager to roll back work done on behalf of a transaction branch.
boolean	setTransactionTimeout(int seconds) Sets the current transaction timeout value for this XAResource instance.
void	start(Xid xid, int flags) Starts work on behalf of a transaction branch specified in xid.

Field Detail

TMENDRSCAN

static final int TMENDRSCAN

Ends a recovery scan.

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Constant Field Values

TMFAIL

static final int TMFAIL

Disassociates the caller and marks the transaction branch rollback-only.

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Constant Field Values

TMJOIN

static final int TMJOIN

Caller is joining existing transaction branch.

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Constant Field Values

TMNOFLAGS

static final int TMNOFLAGS

Use TMNOFLAGS to indicate no flags value is selected.

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Constant Field Values

TMONEPHASE

static final int TMONEPHASE

Caller is using one-phase optimization.

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Constant Field Values

TMRESUME

static final int TMRESUME

Caller is resuming association with a suspended transaction branch.

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Constant Field Values

TMSTARTRSCAN

static final int TMSTARTRSCAN

Starts a recovery scan.

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Constant Field Values

TMSUCCESS

static final int TMSUCCESS

Disassociates caller from a transaction branch.

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Constant Field Values

TMSUSPEND

static final int TMSUSPEND

Caller is suspending (not ending) its association with a transaction branch.

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Constant Field Values

XA_RDONLY

static final int XA_RDONLY

The transaction branch has been read-only and has been committed.

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Constant Field Values

XA_OK

static final int XA_OK

The transaction work has been prepared normally.

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Constant Field Values

Method Detail

commit

void commit(Xid xid,
          boolean onePhase)
            throws XAException

Commits the global transaction specified by xid.

Parameters:

xid - A global transaction identifier

onePhase - 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.

end

void end(Xid xid,
       int flags)
         throws XAException

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 start method 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 the start method.

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*.

forget

void forget(Xid xid)
            throws XAException

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.

getTransactionTimeout

int getTransactionTimeout()
                          throws XAException

Obtains the current transaction timeout value set for this XAResource instance. If XAResource.setTransactionTimeout was 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 previous setTransactionTimeout call is returned.

Returns:

the transaction timeout value in seconds.

Throws:

XAException - An error has occurred. Possible exception values are XAER_RMERR and XAER_RMFAIL.

isSameRM

boolean isSameRM(XAResource xares)
                 throws XAException

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.

prepare

int prepare(Xid xid)
            throws XAException

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.

recover

Xid[] recover(int flag)
              throws XAException

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.

rollback

void rollback(Xid xid)
              throws XAException

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.

setTransactionTimeout

boolean setTransactionTimeout(int seconds)
                              throws XAException

Sets the current transaction timeout value for this XAResource instance. Once set, this timeout value is effective until setTransactionTimeout is 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.

start

void start(Xid xid,
         int flags)
           throws XAException

Starts work on behalf of a transaction branch specified in xid. 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 parameter xid. If neither TMJOIN nor TMRESUME is specified and the transaction specified by xid has 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.