Hi Bertrand, I'll gladly give as much detail as I can, provided you publish the results of your investigation. Is that fair? Each client request creates a separate JMS session, yet they share a single connection per BPEL process. I am unfamiliar with the JBossMQ implementation details, but the JMS spec suggests the JMS connection encapsulates an open socket and sessions take turns to use the transport. Therefore, the impact of mantaining k-sessions is constant in resources (1 socket) and linear in time (k sessions trying to use the transport simultaneously). In practice, even tough you have k active sessions, only a fraction of them will be contending to use the transport. Some of them will be busy preparing the message or waiting for a response. In a jBPM BPEL process, message producers and consumers coexist in the web application where the web services are deployed. Hence, there is no reason for using a socket-based invocation layer. By using the in-JVM layer, sessions do not take turns to use the transport; they deposit messages on the queues directly. When you use a single queue, there will be significant overhead in filtering the messages. jBPM BPEL allows for assigning a separate queue to each partner link in order to alleviate the filtering load. Hope this helps. -Alex View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3976138#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...