What is the difference between Session and Entity Beans in J2EE?

Understanding the Difference between Session and Entity Beans in J2EE

When working with J2EE, it is crucial to understand the distinction between Session beans and Entity beans. These beans are fundamental components of the EJB (Enterprise JavaBeans) architecture, each serving a unique purpose in the application development process.

Session Beans:

Session beans are used to represent a specific client-server session within the application. They are designed to encapsulate business logic and perform specific tasks on behalf of the client. There are two main types of Session beans:

• Stateless Session Beans: These beans do not maintain client-specific state between method invocations, making them lightweight and ideal for performance-critical operations.
• Stateful Session Beans: These beans maintain client-specific state across multiple method invocations, allowing them to store information unique to a particular client session.

Entity Beans:

Entity beans, on the other hand, represent persistent data stored in a database. They are used to model real-world entities such as customers, products, or orders. Entity beans interact with the underlying database to provide CRUD (Create, Read, Update, Delete) operations. There are two types of entity beans:

• Container-Managed Entity Beans (CMT): In CMT, the EJB container is responsible for managing the life cycle and persistence of the entity beans, including database transactions.
• Bean-Managed Entity Beans (BMT): With BMT, the developer is responsible for explicitly managing the persistence and transactions of the entity beans, providing more control but also requiring more manual coding.

In summary, Session beans are used to encapsulate business logic and manage client-specific interactions, while Entity beans represent persistent data stored in a database. Understanding the differences between these two types of beans is essential for designing robust and efficient J2EE applications.