As I have said, I believe more than a few times now, the 4.0.5 code was backported randomly and really should never have been done (believe me, I yelled and screamed about this for quite awhile but to no avail). The code in HEAD should really be ported or installed as a patch. Please note, just because JCA starts/terminates a transaction does not mean that the onMessage method executes in this context. If NotSupported or BMT is used, the EJB container will suspend the transaction appropriately. anonymous wrote : | Hmmm, it seems that if I omit the acknowledge-mode from the MDB deployment descriptor when using BMT, then it defaults to transacted. | No, it's not. acknowledgement modes are used only in the case of a *non* tranascted session. The spec is merely saying that if the client is using a transacted session, then the ack mode is AUTO_ACKNOWLEDGE which is just simply a convention in this case as has no overall effect. anonymous wrote : | Instead, it should be creating a non transacted session, on a non xa connection and not calling commit at the end since it's non transacted. | No, it doesn't. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4001387#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...