I can't quite get the reason we have to place this file in a portlet deployment.
I assumed, it might help unifying several deployed war's under one application. When I tested this (when I tried to deploy several several war's containing portlets containing the same application name in jboss-app.xml), I got the exception that this application is already deployed and the war had rejected to deploy.
Then I removed the jboss-app.xml from one of the wars and try to use the application name in component-ref element in the -object.xml then portal complained this application name belongs to another war.
So if jboss-app.xml is not there to unify several wars/portlets under to one application, what is the resaon of its existence.
The reason I tried all this, when we have portlets that are deployed from different war's, they are not able to share portlet session, which is a requirement from the Servlet specification I guess, I just hope if I can unify them under one application name, they might share the same portlet session.
Anyway what is the use of the jboss-app.xml in this case?