Yes, but the jars from the client directory isn't in the servers runtime classpath so those shouldn't have any effect? The booking structure isn't too easy to put into words, but it consists of a set of rather heavy dataholder classes (lots of class fields) and collections of similar classes multiple levels down. One thing though; don't see why serialization is involved between the ejb's, rightly they are in separate ears, but still by ref should be possible. And in the callstack it seems local interface semantics is beeing used (from: org.jboss.ejb3.remoting.IsLocalInterceptor.invoke()), so shouldn't these values be sent by reference? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3970918#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...