I must be missing something. I setup a queue to a MDB under JBoss 4.0.1 default configuration and everything appears to be working correctly. Auto-acknowledge is turned on. However, when the message is sent, it seems to behave synchronously all the way from the send through executing the onMessage method of the MDB. In other words, the send for a non-transacted message waits for the MDB to complete processing before returning. The commit for a transacted message behaves similarly. Perhaps it's my ignorance of JMS, but I expected that at most the delivery of the message to the queue would be synchronous, not the MDB execution. The whole purpose of using JMS in this case was to delegate a long-running operation to the MDB so that the sender could continue without waiting for results. Is there something else I need to be doing? Thanks. Bob View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4045093#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...