There are three types of enterprise bean in java.
Entity Bean : Entity Bean is a server-side component that represents the persistent data. Since EJB 3.x, it is replaced by JPA.
Session Bean : Session Bean encapsulates business logic. It can be invoked by local, remote or web service client. There are 3 types of session bean.
* Stateless Session Bean
* Stateful Session Bean
* Singleton Session Bean
Message Driven Bean : Message Driven Bean (MDB) encapsulates business logic. It is invoked by passing the message. It is like JMS receiver.
