We have a EJB project that contains about 10 EJBs that are common to
most of our web and client applications. As the EJB are generic, so to
speak, this is packaged and deployed as the only thing in the ear
file. Everything works fine except for when we need to change any of
these EJBs and redeploy. When we redeploy, everything appears to
redeploy properly but the webapps then start generating class cast
exceptions and the only way to fix it is to restart jboss or redploy
every app that uses the ejbs. This happens on our single jboss server
and the 10 clustered machines we have (running jboss4.0.1sp1 on gentoo
with one the machines set-up as loadbalancer using mod_jk and apache).

Is this expected behaviour?
What is standard practice for this sort of common code. I am at a loss
as to how we can deploy to a live enviroment without any impact on the
users and client applications. I thought that this is what hot
deployment is all about but it doesn't seem to work.

BTW all the EJBs are stateless session beans that just provide glue
between web apps/clients and the Business Classes (using Data Factory
pattern).

I have asked the same question on the jboss forums but no one is
replying.  This may be a implementation issue.
I am not sure if the way in which I have designed the applications are
the correct j2ee way but I can find no pattern for common business
objects and ejbs.  I need to have one location with this code in that
can be referenced across various web and client apps, which is why I
chose ejbs as I thought this is what they are designed for!