JmsXA is connection factory that is deployed by the
JCA resource adaptor. This allows the ejb transaction
to enlist the XAResource (this is done behind the scenes
you don't need to worry about it).
When using the JmsXA connection factory, you are actually
dealing with a very thin facade on top of pooled XASessions.
stop() is only applicable if you previously invoked
start() for message delivery (it is not recommended
for ejbs to become receivers)
Today I discovered that the JBoss 2.4 docs contain some info on this subject, which seems to be still valid for 3.2 for the most part.