As of JBoss 3.2.1 is it possible to get more information about OracleXAException. To enable this feature, edit oracle-xa-ds.xml and uncomment OracleXAExceptionFormatter mbean. (to verify that it worked, restart JBoss server, go to JBoss management console and make sure that there is jboss.jca:service=OracleXAExceptionFormatter mbean).
For each Oracle XA exception you will now get additional record in /log/server.log file that looks like
2003-05-14 08:00:01,169 WARN [org.jboss.tm.TransactionImpl] xa error: -4 (The XID is not valid.); oracle error: 24756; oracle sql error: 0;
oracle.jdbc.xa.OracleXAException
at oracle.jdbc.xa.OracleXAResource.checkError(OracleXAResource.java:659)
at oracle.jdbc.xa.client.OracleXAResource.end(OracleXAResource.java:300)
at org.jboss.resource.adapter.jdbc.xa.XAManagedConnection.end(XAManagedConnection.java:146)
at org.jboss.tm.TransactionImpl.endResource(TransactionImpl.java:1194)
at org.jboss.tm.TransactionImpl.endResources(TransactionImpl.java:1267)
...
