So, if I'm understanding this correctly, JBoss ESB supports QOS_ONCE_AND_ONLY_ONCE but only if both sides are XAConnectionFactory? If so that's nice... I may be able to work with that. How is this configured (enabled/disabled)? I'd prefer QOS_DUPLICATES_OK for reasons Tim Fox got into. I don't think this should be hard; just wait until the service is done and THEN acknowledge the JMS message from the gateway. I don't need batching... but Tim gave reasons why that's good too. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4139391#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...