It may appear quite obvious that any Spring based web application that works under Tomcat should be working when deployed to JBoss EAP 5.1. In fact, this is further than the truth. Most often than not, the Spring based web application would just spew out tones of exception messages. This is exactly what happened when I tried to deploy a Spring 3.0.5/Hibernate 3.5.6 web application to JBoss EAP 5.1. I did finally get the application to work but not after spending many hours of trial and error to figure out the exceptions. Here are my eventual fixes.
1. Removed all the XML parsers under WEB-INF/lib directory, i.e. xmlParsers, xml-api, xalan, xerces.
2. Added hibernate-validator-4.1.0.Final.jar to WEB-INF/lib directory. For some unknown reason, JBoss EAP 5.1 absolutely need this.
3. Add 2 entries to hibernate.properties to pass into Spring. See text in red below.
With these changes, the web application finally works.