J2EE specification

This topic describes the J2EE specification that is the foundation of the application programming model for WebSphere Application Server. WebSphere programming model extensions add value by extending the J2EE programming model. Read this topic for a brief overview of key J2EE concepts, including the parts of the J2EE runtime environment and J2EE application packaging and deployment.

The J2EE specification is the standard for developing, deploying, and running enterprise applications. The ultimate source of information is the specification, which is available on the Sun Microsystems, Inc., Web site at http://java.sun.com. The WAS documentation provides links and J2EE descriptions for convenience only.

Quick reference: primary J2EE 1.4 specifications

IBM WebSphere Application Server, V6 has completed the full J2EE certification test suite. The product supports all of the J2EE 1.4 APIs. You can check the list of J2EE-compatible products posted by Sun Microsystems at http://java.sun.com/j2ee/compatibility.html.

Java 2 Platform, Enterprise Edition defines a standard that applies to all aspects of designing, developing, and deploying multi-tier, server-based applications. The standard architecture that is defined by the J2EE specification is composed of the following elements:

The J2EE platform specification describes the run-time environment for a J2EE application. This environment includes application components, containers, and resource manager drivers. The elements of this environment communicate with a specified set of standard services. For more information, see Three-tier architectures.

 

J2EE platform roles

The J2EE platform also defines

a number of distinct roles that are performed during the application development and deployment life cycle:

Product providers and tool providers have a product focus. Application component providers and application assemblers focus on the application. Deployers and system administrators focus on providing the J2EE application with platform-specific artifacts, and on the platform run time.

These roles help identify the tasks and people involved. Understanding this separation of roles is important because it helps to determine the approach when developing and deploying J2EE applications.

For information about roles that are assumed by this product documentation, see Fast paths for WebSphere Application Server.

 

J2EE benefits

The J2EE specification provides customers a standard which can be used to ensure investment protection when purchasing or developing applications. Comprehensive, independent Compatibility Test Suites ensure vendor compliance with J2EE standards.

Some benefits of deploying to a J2EE-compliant architecture include:

The J2EE specifications are the result of an industry-wide effort that involves a large number of contributors. IBM has contributed in defining more than 80 percent of the J2EE APIs.

For a description of the programming model of the product, see WebSphere applications: Overview and new features.

 

Application components and their containers

The

J2EE programming model has four types of application components, which reside in these types of containers in the Application Server:

For a description of the product architecture, see Product architecture.

J2EE containers provide runtime support for application components. There must be one container for each application component type in a J2EE application. By having a container between the application components and the set of services, the J2EE specification can provide a federated view of the APIs for the application components.

A container provides the APIs to the application components that are used for accessing the services. The container can also handle security, resource pooling, state management as well as naming and transaction issues.

 

Standard services

The J2EE platform provides components with a set of standard services that they can use to interact with each other. See the Sun products Web page for descriptions of each standard service.

 

J2EE packaging

During a process called assembly, J2EE components are packaged into modules. Modules are then packaged into applications. Applications can be deployed on the application server. Each module and application contains a J2EE deployment descriptor. The deployment descriptor is an XML file that provides instructions for deploying the application. For product-specific details, see Assembling applications.


 

See Also


Product architecture
WebSphere applications: Overview and new features

 



 

 

WebSphere is a trademark of the IBM Corporation in the United States, other countries, or both.
IBM is a trademark of the IBM Corporation in the United States, other countries, or both.