What is EJB
Portable, reusable, scalable applications platform
Why choose EJB
1. Easy to use, by the EJB container to provide a lot of services, developers only need to focus on the business code
2. Integrated solution suite, provided by the application server a large number of services
3. JavaEE standards
4. Extensive vendor support
5. Stable, high-quality code base
6. Cluster, load balancing, failover
7. Easy to develop allowable reusable components
The service that provided by EJB container
1. Integration
2. Pooling
3. Thread security
4. State management (for stateful session beans)
5. Message server (for message-driven bean)
6. Transaction management
7. Security
8. Interceptors
9. Remote call
10. Web services
11. Persistence
12. Cache
13. Performance optimization
New features of EJB3.X
1. Simplify the design of the program model, based on POJO design
2. Support annotations
3. Supports dependency injection and JNDI
4. Simplified persistence API
5. POJO components that can be unit tested
Reference