EJB 3.1 Component Types

EJB 3.1 component types are:

1. Session Beans
1. Stateless Session Beans (SLSB)
2. Stateful Session Beans (SFSB)
3. Singleton Session Beans
2. Message Driven Beans (MDB's)
3. Entity Beans

• The Stateless Session Bean does not preserve conversational state.
• The Stateful Session Bean preserves conversational state and there is one instance of the session bean per client.
• The Singleton Session Bean is new to the EJB 3.1 Specification. There is only one instance of this bean type.
• The Message Driven Bean acts as an event listener. It cannot be called from the client.

For each Bean, there are lifecycle callbacks that must follow the pattern void <METHOD>().