The Enterprise JavaBeans Tier

by Inderjeet Singh, Linda DeMichiel, and Beth Stearns

In a multitier J2EE application, the Enterprise JavaBeans (EJB) tier hosts application-specific business logic and provides system-level services such as transaction management, concurrency control, and security. Enterprise JavaBeans technology provides a distributed component model that enables developers to focus on solving business problems while relying on the J2EE platform to handle complex system-level issues. This separation of concerns allows rapid development of scalable, accessible, robust, and highly secure applications. In the J2EE programming model, EJB components are a fundamental link between presentation components hosted by the Web tier and business-critical data and systems maintained in the enterprise information system tier.

This chapter describes the concepts central to the Enterprise JavaBeans architecture and provides guidelines and recommendations to best use EJB components. The chapter:

• Examines the nature of business logic and describes the problems a developer needs to resolve when implementing business logic
• Describes the component model that Enterprise JavaBeans architecture provides to address these problems
• Describes remote and local client views
• Provides details on the three types of enterprise beans: entity beans, session beans, and message-driven beans
• Recommends design guidelines for developing EJB components and applications
• Presents recommendations and practices to best utilize the EJB tier services provided by the J2EE platform
• Provides guidelines to facilitate application portability