Chapter 4. Transaction Recovery

During recovery, the Transaction Manager needs the ability to communicate to all resource managers that are in use by the applications in the system. For each resource manager, the Transaction Manager uses the XAResource.recover method to retrieve the list of transactions currently in a prepared or heuristically completed state. Typically, the system administrator configures all transactional resource factories that are used by the applications deployed on the system. The JDBC XADataSource object, for example, is a factory for the JDBC XAConnection objects.

Because XAResource objects are not persistent across system failures, the Transaction Manager needs the ability to acquire the XAResource objects that represent the resource managers which might have participated in the transactions prior to a system failure. For example, a Transaction Manager might use the JNDI look-up mechanism to acquire a connection from each of the transactional resource factories, and then obtain the corresponding XAResource object for each connection. The Transaction Manager then invokes the XAResource.recover method to ask each resource manager to return the transactions that are currently in a prepared or heuristically completed state.

If the JBossJTA JDBC 2.0 driver is in use, JBossJTA manages all XAResource crash recovery automatically. Otherwise one, of the following recovery mechanisms is used: