Weston - what is the correct behaviour of the JCA JMS managed connection factory here? Just to recap: If I obtain a session from a connection created from the JCA JMS managed cf (i.e. the one normally at java:/jmsXA), and there is *no* JTA transaction associated with the current thread, and I receive a message, should the session act like a non transacted session and the message get acknowledged immediately, OR should it act like a transacted session? This is the key question. If it should act like a non transacted session, how can we reconcile this with transactional message receipt for MDBs? In a MDB the message is received *before* the MDB container has a chance to start a global tx, therefore it is received in a session where no JTA tx is associated with the current thread. In this case we must *not* ack it immediately, but we must let the session behave as a transacted session and later when the MDB container starts a JTA tx and enlists it, we can transfer the work done in the local tx into the global tx. Funnily enough - transferring the work into the JTA tx is exactly how JBoss MQ does it too, so I am puzzled as to how this behaviour is consistent with the behaviour of JCA without a JTA tx as Ovidiu reports. This is why I am trying to find out whether the supposed JCA behaviour is real or bogus. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3998913#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...