Packaging an Application With Both EJB 3.0 and EJB 2.1 Enterprise Beans

You can combine both EJB 3.0 and EJB 2.1 beans in your application. For example, you could have an application that contains three annotated EJB 3.0 entities without ejb-jar.xml file, two EJB 2.1 entity beans with ejb-jar.xml file, and three EJB 3.0 session beans with ebj-jar.xml file, annotations, or both (in which case, the ejb-jar.xml overrides the annotations).