- EJB Tutorial
- EJB - Home
- EJB - Overview
- EJB - Environment Setup
- EJB - Create Application
- EJB - Stateless Bean
- EJB - Stateful Bean
- EJB - Persistence
- EJB - Message Driven Beans
- EJB - Annotations
- EJB - Callbacks
- EJB - Timer Service
- EJB - Dependency Injection
- EJB - Interceptors
- EJB - Embeddable Objects
- EJB - Blobs/Clobs
- EJB - Transactions
- EJB - Security
- EJB - JNDI Bindings
- EJB - Entity Relationships
- EJB - Access Database
- EJB - Query Language
- EJB - Exception Handling
- EJB - Web Services
- EJB - Packaging Applications
- EJB Useful Resources
- EJB - Quick Guide
- EJB - Useful Resources
- EJB - Discussion
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
EJB - 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 Bean Session 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 Bean Entity 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 Bean Message 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.