Chapter J2EE.1. Introduction

Enterprises today need to extend their reach, reduce their costs, and lower their response times by providing easy-to-access services to their customers, employees , and suppliers.

Typically, applications that provide these services must combine existing Enterprise Information Systems (EISs) with new business functions that deliver services to a broad range of users. These services need to be:

• Highly available , to meet the needs of today's global business environment.

• Secure , to protect the privacy of users and the integrity of the enterprise.

• Reliable and scalable , to insure that business transactions are accurately and promptly processed .

In most cases, these services are architected as multi-tier applications. A middle tier that implements the new services needs to integrate existing EISs with the business functions and data of the new service. The service middle tier shields first- tier clients from the complexity of the enterprise and takes advantage of rapidly maturing web technologies to eliminate or drastically reduce user administration and training while leveraging existing enterprise assets.

The Java 2 Platform, Enterprise Edition (J2EE) reduces the cost and complexity of developing these multi-tier services, resulting in services that can be rapidly deployed and easily enhanced as the enterprise responds to competitive pressures.

J2EE achieves these benefits by defining a standard architecture that is delivered as the following elements:

• J2EE Application Model ” A standard application model for developing multi-tier, thin-client services.

• J2EE Platform ” A standard platform for hosting J2EE applications.

• J2EE Compatibility Test Suite ” A suite of compatibility tests for verifying that a J2EE platform product complies with the J2EE platform standard.

• J2EE Reference Implementation ” A reference implementation for demonstrating the capabilities of J2EE and for providing an operational definition of the J2EE platform.

This document provides the specification of the J2EE platform and describes the requirements that a J2EE platform product must meet.