How are message driven beans different from session beans and entity beans?

A message-driven bean is a type of EJB (Enterprise JavaBean) that provides asynchronous communication. A message-driven bean’s instance handles only one client message at a time, which is short-lived. The message from the client arrives through JMS (Java Message Service) and is transferred to the message-driven bean’s instance via the EJB container. Message driven beans are different from session beans and entity beans in the following ways:

• Message driven beans have only a bean class.
• Message driven beans are not accessible by the clients through interfaces.
• Message driven beans receive messages asynchronously.
• A message driven bean retains no data for a client.
• All instances of message driven beans are equivalent and the container can pool these to allow stages of messages to process simultaneously.
• Message driven beans can process messages from multiple clients.

• Previous Entry: What are the advantages of entity beans over session beans?
• Next Entry: What is a Web service?