The specifications – Associated with the main J2EE technologies are documents that describe how the technologies can be expected to work in an enterprise environment and how developers can use them in this context.

The reference implementation – Like many Java technologies, J2EE has a sample implementation available to both developers and vendors so that it's possible to work with a baseline implementation of the technology. It implements the core J2EE APIs and provides a Web container, EJB container, relational database and various tools for testing and deploying J2EE applications.

Blueprints for J2EE – Guidelines for creating enterprise applications, and best practices for J2EE development.

The sample application – The Java Pet Store provides an open-source sample J2EE application to demonstrate how the architecture can be used in practice.

Compatibility testing – Vendors who want to develop J2EE-compliant servers can use a Compatibility Test Suite to validate that their applications fully support the specification.

Component Patterns

The three major component technologies for J2EE are EJBs, JSPs, and servlets. Although there is potentially a fourth technology in Applets, a potential technology for Client-tier Web applications, it is less central to the core J2EE model. In the sections that follow, we'll discuss the three component APIs and present the design patterns that they implement.

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