We're getting compile-time and runtime requirements mixed here. Yes, it's a valid tenant of OOP to accept any subclass of Object in your cache. However, for the JVM to work with objects, it must first load the Class that defines it, meaning the .class definition must be available to the ClassLoader. In the case of EJB3, each "Container" has its own ClassLoader (allocated at deployment/container construction), and this CL does not support loading bytes from a remote location (which would be required for this use case). So long story short is that all class definitions must be available on the server for them to use used. S, ALR View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4177735#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...