Probably not, after all there's nothing stopping the user from just calling setListener() on the session. It would be pretty pointless but not illegal. The if would be only session.isXA() && distinguishedSesion!=null. And that wouldn't invalidate any customer's usage. This would only assume the ACK will be done transactionally. I think this should be fine and better than instanceof then. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4041901#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...