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In this guide we will discuss about EJB Home. Enterprise Java Beans (EJB) is a development architecture for building highly scalable and robust enterprise level applications to be deployed on J2EE compliant Application Server such as JBOSS, Web Logic etc.

EJB 3.0 is being a great shift from EJB 2.0 and makes development of EJB based applications quite easy.

This tutorial is developed to provide a comprehensive understanding about the EJB concepts helpful to create and deploy an enterprise level application up and running.

Audience

This tutorial is designed for Software Professionals as well as for all those who are willing to learn EJB Programming. This tutorial will give you a great understanding about EJB Programming concepts in simple and easy steps.

Prerequisites

Before proceeding with this tutorial, you should have a basic understanding of Java programming language, text editor, and execution of programs etc. Because we are going to develop enterprise-based applications using EJB, it will be good, if you have understanding on other technologies like Database Servers, Application Servers.

Overview

EJB stands for Enterprise Java Beans. EJB is an essential part of a J2EE platform. J2EE platform has component based architecture to provide multi-tiered, distributed and highly transactional features to enterprise level applications.

EJB provides an architecture to develop and deploy component based enterprise applications considering robustness, high scalability, and high performance. An EJB application can be deployed on any of the application server compliant with the J2EE 1.3 standard specification.

We’ll be discussing EJB 3.0 in detail in this tutorial.

Types

EJB is primarily divided into three categories; following table lists their names with brief descriptions −

S.No	Type & Description
1	Session BeanSession bean stores data of a particular user for a single session. It can be stateful or stateless. It is less resource intensive as compared to entity bean. Session bean gets destroyed as soon as user session terminates.
2	Entity BeanEntity beans represent persistent data storage. User data can be saved to database via entity beans and later on can be retrieved from the database in the entity bean.
3	Message Driven BeanMessage driven beans are used in context of JMS (Java Messaging Service). Message Driven Beans can consumes JMS messages from external entities and act accordingly.

Benefits

Following are the important benefits of EJB −

• Simplified development of large-scale enterprise level application.
• Application Server/EJB container provides most of the system level services like transaction handling, logging, load balancing, persistence mechanism, exception handling, and so on. Developer has to focus only on business logic of the application.
• EJB container manages life cycle of EJB instances, thus developer needs not to worry about when to create/delete EJB objects.

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