With XA 2PC, a camel route, jms 'to' jdbc should ensure exactly once delivery to jdbc. In the event of a failure after prepare, where commit to jdbc is done, the jms message must remain with a pending ack till the commit outcome is relayed from the transaction manager.
Current versions of geronimo will correctly retry the commit in a timer thread, so activemq eventually gets the commit outcome after recovery. (btw: it looks like howl will not persist a commit outcome per NamedXAResource, so after a failure of the TM it may consier the transaction completed and the message may still be pending, need to check that!)
At the moment, ActiveMQ does a heuristic rollback after recovery which leads to message redelivery in error.
With the fix, an acked message remains pending awaiting the outcome. On commit, the message is acked. On rollback the message is available for redelivery.