Professional Java Servlets 2.3

Overview

Java is a mature technology that can be broken down into separate platforms. You should already be familiar with the Java 2 Platform, Standard Edition (J2SE). J2SE provides the core Java APIs and the Java Virtual Machine (JVM), as well as development tools such as the Java compiler. However, in this book we're going to concern ourselves with Java 2 Platform, Enterprise Edition (J2EE). In fact we're going to concentrate on one part of J2EE - the Java Servlet 2.3 API.

J2EE builds upon J2SE, providing APIs and services for developing and deploying enterprise applications. Together the services and libraries of J2SE and J2EE enable the development of platform-independent, web-based Java applications. The J2EE platform also enables server vendors to provide environments in which the J2EE applications can be deployed and run.

• In this chapter we're going to begin by considering enterprise architecture with distributed applications, and the tiers involved in web application development.

• We will then examine how the J2EE architecture facilitates web development via web containers and Java servlets, and discuss the J2EE services and libraries that servlet developers may want to consider including in their applications.

• We will also discuss the advantages of using Java servlets that comply with the Servlet 2.3 specifications in our web applications.

• This will lead to a discussion of the roles that container vendors and developers have to play in implementing the Servlet specifications, and an introduction to the Tomcat web container/server, which is the reference implementation of the Servlet specifications.

• To round off the chapter, we will take a look the roles that servlets have to play in modern enterprise applications, which should hopefully illustrate their relevance and importance to enterprise application development.

However, before we begin to look at servlets in detail, let's take a high level view of enterprise architecture.