I don't understand what the issue is here. The userguide explicitly states which jars you need on your classpath, and where to obtain them, and what versions you require: See http://labs.jboss.com/file-access/default/members/jbossmessaging/freezone... concurrent.jar is inside jbossall-client.jar Are you saying that you get problems when using the jars specified in the userguide? Or are you saying that you are having problems when you use a different set of jars on the client to what is specified in the guide? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4058850#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...