The XAException is thrown by the Resource Manager (RM) to inform the
Transaction Manager of an error encountered by the involved transaction.

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.

The Xid interface is a Java mapping of the X/Open transaction identifier
XID structure. This interface specifies three accessor methods to
retrieve a global transaction format ID, global transaction ID,
and branch qualifier. The Xid interface is used by the transaction
manager and the resource managers. This interface is not visible to
the application programs.