the asm lib is a known issue with JRuby and Hibernate. This kind of trouble is in fact more a Java jar issue than a JRuby one and occurs frequently as soon as you integrate large frameworks together.

Still, I don’t really understand why you get the issue (or may be it’s only in Maven?). Indeed, JRuby works arround that issue by repackaging asm.jar using the ‘jarjar’ tool. Thus, if you look inside jruby-complete.jar you’ll see that it’s repackaged into jruby.objectweb.asm … which is different from the asm of the Hibernate distro.

So I don’t really understand why you are getting the problem since asm classes aren’t colliding anymore. Did you really use jruby-complete and jruby-complete only? Is it a Maven issue?

I think you should really be able to work arround the problem: lot’s of others successfully used Hibernate in JRuby. There is even the ActiveHibernate lib wrapping Hibernate object better into Ruby objects:
http://code.google.com/p/activehibernate/

Hope this helps. You might also get help from the JRuby mailing list.

Raphaë Valyi.