Datasheet

Chapter 1 ✦ Understanding Java and the J2EE Platform

Understanding J2SE

Around 1998, Sun updated the Java specification and introduced Java 1.2 along with

the accompanying libraries, making Java not only a language, but also a platform —

Java 2 Standard Edition (J2SE). Prior to the release of J2SE, Java had gone through

the number of revisions and new libraries were not necessarily introduced in a con-

certed manner, making it difficult for developers to understand. Prior to the J2SE,

the Java Development Kit (JDK) was the primary package that was installed, and

developers would choose which additional libraries they would want such as Java

Database Connectivity (JDBC) or Swing. This led to inconsistent environments mak-

ing it difficult to port code since the deploying party would not be guaranteed of

the libraries on the deployment platform.

JDBC is the topic of Chapter 18.

With J2SE, Sun attempted to fix the problem by bundling the various libraries into

a single unit. J2SE provided libraries for GUI support, networking, database access,

and more. J2SE is also the foundation for the J2EE.

Examining the Origin of (J2EE)

J2SE was sufficient for developing stand-alone applications, but what was missing

was a standard way to develop and deploy enterprise applications—one similar to

the standard method for using the Common Object Request Broker Architecture

(CORBA). While J2SE already included enterprise-level APIs such as Remote Method

Invocations (RMI), too much was still left undefined — such as persistence, transac-

tion management, security, and so on. This resulted in a plethora of architectures

being developed.

J2EE, introduced in 1998, defines a multi-tier architecture for enterprise information

systems (EIS). By defining the way in which multi-tier applications should be devel-

oped, J2EE reduces the costs, in both time and money, of developing large-scale

enterprise systems. Figure 1-2 illustrates the J2EE architecture, highlighting the new

additions within the 1.4 release.

The J2EE platform specifies the logical application components within a system and

defines the roles played in the development process.

Cross-

Reference

c539663 ch01.qxd 7/25/03 9:13 AM Page 5