I'll throw together a test app to demonstrate in a bit as my project is quite large and proprietary. However, you mentioned part of the problem: my ejb does not have the implementation on the classpath. But that is sort of the point of the system. I'm trying to get it to just take Objects - any Objects. I don't want to do anything with them accept store them in a cache which itself doesn't care about implementations either. The problem, it appears, is that JBoss does care about implementations. I want to work with any Object, but JBoss appears to require certain types, specifically those defined in the interface and not their subclasses. That's what's causing my problem. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4177654#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...