The Enterprise JavaBeans architecture or EJB for short is an architecture for the development and deployment of component-based robust, highly scalable business applications. These Applications are scalable, transactional, and multi-user secure. You can develop the application once and then deploy on any one of the JEE 5 complaint application server. There are many application servers are available both free and commercial. You can choose the server for development and deployment to suit your requirement and budget.
EJB 3.0 New Features
Following are the new features of EJB 3.0:
1. Metadata Annotations
EJB 3.0 extensively uses the metadata annotations to simplify the development of EJB 3.0 components. Now there is no need to write the deployment descriptor, but the deployment descriptor is still supported. Annotations can be overridden by deployment descriptor.
2. Encapsulation of environmental dependencies
EJB 3.0 now uses the annotations and dependency injection mechanism to encapsulation the environmental dependencies and JNDI access.
3. More simplified EJB Specification
EJB 3.0 is simplified Specification but still very powerful. Now there is no need to write home and component interfaces and implementing the javax.ejb.EnterpriseBean interface by EJB class. The EJB bean class is now pure java class, also know as POJO and the interface is know as POJI is simple Java interface. So, you can now developed your enterprise application very fast.
4. Dependency Injection
Now the API for lookup and usage of EJB environment and resource references has been simplified and dependency injection is used through metadata annotations.
5. Simplification of Entity Persistence
Persistence of the entity objects are now very simple through the introduction of Java Persistence API. A new API EntityManager API has been introduced is used create, find, remove and update entities. Now the domain objects supports inheritance and polymorphism.
6. Callback interfaces
Elimination of the requirement for the implementation of callback interfaces.
For more information,Examples and Tutorials on EJB visit to :http://www.roseindia.net/ejb/http://www.roseindia.net/java/jee5/what-is-ejb3.shtml