JBoss AS7 is a major re-write of the JBoss application server with a modular architecture and improved performance. Key features include HornetQ as the default JMS provider, the JBoss module system for classloading, and support for CDI, JSF, RESTEasy and other Java EE 6 specifications. Testing can be simplified using Arquillian which integrates tests directly with the application server container. Migrating from earlier versions of JBoss AS requires changes to configuration, dependencies and tooling.