Do we need JacORB library in the boot classpath? The short answer: yes. Its due to bug in the Sun implementation of FixedHolder._type() method in the org.omg.CORBA package. The Suns implementation does not return any information about digits and scale, the JacORB - guess what - properly does. There were many discussions in the JacORB mailing list if we do need jacorb.jar in the Java boot classpath. Yes, JacORB will run when you use only classpath but expect the unexpected.

You ignore this fact. At least if I understand the JBoss class loading machinery properly - the jacorb.jar is just dropped in the server/all/lib directory. Its in the classpath - the Suns broken implementation is used then. If you call EJBs via CORBA in JBoss please expect the unexpected.