JBoss 7.1.x introduced a new way to start a JavaEE application client: now the batch file "bin\appclient.bat" or "bin/appclient.sh" has to be used. I don't know the details of this file, but it basically starts a small application server, initializes e.g. JNDI and starts the main file of the app client.

This approach is needed if the app client has to use the Environment Naming Context or even uses EJB injection.
See this forum thread for some more details and a sample app: https://community.jboss.org/thread/195232

It would be very helpful (especially for newbies) if an JavaEE application client could be started the same way directly inside Eclipse.