• EJB (Enterprise Java Beans) is a server-side component that executes specific business logic.
• It enables development and deployment of component based, robust, highly scalable & transactional business application.

1 ) EJB Server :

• It provides execution environment for server components.

• It hosts EJB containers.

2) EJB Container:

• It serves as interface EJB and Outside World.

Container hosts following components:

• EJB Object: A client invokes beans instance through EJB Object. It is called Request Interceptor.

• Remote Interface: It duplicates machines of bean class.

• Home Object: It is the object factory bean where client can create or destroy object.

• Home Interface: It provides machine for creating and destroying, finding bean object.

• Local Interface: It is used instead of EJB objects for faster access.

The type of container depends on beans they contains i.e either transient or persistent beans.

3) Enterprise Beans:

• They are EJB Components that encapsulates business functionalities in an application.

• Container provides security to enterprise beans.

• Types of Enterprise Beans:

  • Session Beans(Synchronous)

  • Message Driven(Asynchronous)

  • Entity Beans (Data/Records in DB).

4) EJB Client:

• It makes use of EJB beans to perform the operations.

• Client locates the container using JNDI (Java Naming & Directory Interface)

• Then the client invokes JB Beans machines through container.

5) Deployment Descriptor:

• It lists the bean properties and elements like :

  • JNDI Name for Bean.

  • Home and Remote Interface.

  • Bean Implementation Class.

  • Environment Variables.

  • Access Rules or Rights.

  • Beans Management, Etc.