Classloader - Sharing common files between web and ejb tier

[logankiefer]

Is there a way to have shared libraries between war and ejb but have it so that the shared libraries are isolated in each tier. In other words if I had a shared class that the war classloader would load it and the ear classloader would load it, but any changes to that class in the web tier would not effect the instance in the EJB tier. And the war and ear run in the same JVM.

The reasoning behind this is that we developed common classes that were shared among web and ejb tier when they were in separate JVMs. Now that we are in same JVM we don't want any ill-side effects that could occur since now that common class is going to be manipulated by both tiers. This concern is mostly for shared static classes or singeltons.

[logankiefer]

Another way of putting it is that I want the common classes to not be shared between the servlets and ejbs, where the servlets and ejbs are in the same jvm.

[logankiefer]

Reading the JBoss classloader chapter very carefully I believe I why my request my not be possible unless I create my own classloaders. JBoss associates the ear archive with a UCL (shared repositiory). The ejb jar and the web war archives are added to the ear's UCL classpath and thus automatically share and resources loaded in this UCL.

So unless I write a classloader that separates the war's assocation with the UCL shared repository the ear and ejb libraries will always be visible to the war. So if I put a common library in the war and the ear their will be class loader isssues.

[logankiefer]

Does anyone think that isolating common classes between servlet and ejb tier is a just plain wrong and should never be attempted?