I think such a tool is a good stop gap measure but in general I think our perspective on this is all wrong. We have a great modular framework and isolated classloading. Its a framework that can support applications running different lib versions on it. Why not leverage that more? It's the changes to the server framework implementation that seems to always cause the most pain in moving an application from one server version to another. AS7 is a case in point. Providing a new improved framework is a good thing but why not provide an infra-structure (module) along with it to enable the move from the previous to the current seamless? Why make the customer do so much hard work? We've all seen the forum discussion where a user is attempting to migrate their AS 4 app lock stock and barrel to AS 7 and ask how to resolve related errors? I too have scratched my head and asked, "why would he ever want to do that". Well, the user has put in a lot of man hours writing that app, fixing bugs, and making it stable. He does not want to take the risk of introducing any new bugs with changes. He does want to write his new code to the current standard and run it in the current environment and he wants a single server environment to do it in. I've always envisioned JEE implementations to be an environment much like an OS. When I update my OS I don't have to alter any of the apps I'm running. I don't have to redeploy them or reconfigure them in any way. It just works. I expect the same of my JEE implementations, and to date I've been disappointed by all the vendors. I think the framework provided in AS 7 and WildFly empowers us to provide an JEE environment that supports that AS 4 app running unaltered in WildFly. I think there a number of functions that can and should be *retrofited* to WildFly. The Hibernate 3 module is an example of this. An AS4/AS5 server config loader module is another. Support for the predecessors of HornetQ and Infinispan are others. As we move forward with WildFly and future versions I would argue we need to design seamless support for prior versions of the components and provide backward compatibility not just at the JEE api level but the server framework implementation level. (Treat it like an OS)