Sun ONE Application Framework Tutorial

This chapter outlines the mechanics of using the Sun ONE Application Framework tools to build a J2EE Web application.

This chapter contains the following topics:

• Introduction
• Writing Sun ONE Application Framework Applications
• About the Sun ONE Application Framework Tutorial

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Introduction

This document introduces developers to the mechanics and techniques used to build Web applications with the Sun ONE Application Framework tools.

It is intended for developers who are at least somewhat familiar with building Web applications using existing J2EE Web technologies (servlets and JSPs), but new to building Web applications with the Sun ONE Application Framework.

This document assumes Java expertise and familiarity with the development and deployment procedures for the specific servlet container and development tools being used.

Because the Sun ONE Application Framework is foremost a design pattern and a set of interfaces, the examples in this document show only the most basic way of creating a Sun ONE Application Framework application, by extending existing Sun ONE Application Framework implementation base classes and manually constructing certain application objects. This is only one possible way to create a Sun ONE Application Framework application.

There are two reasons for not showing more advanced techniques in this document. First, starting at a fundamental level is the most direct way to impart how the Sun ONE Application Framework works to someone new to the framework. Being able to see exactly how the framework interacts with the application is critical to getting the most out of the Sun ONE Application Framework.

Second, building an application using these fundamental techniques is a prerequisite to fully understanding the many possible ways to build Sun ONE Application Framework applications. Features that extend the Sun ONE Application Framework to add additional capabilities are built on the techniques demonstrated in this document. After understanding these basic examples, you have a greater understanding of how these features extend and complement the Sun ONE Application Framework core, and you are able to optionally decide not to use them and instead construct your own Sun ONE Application Framework extensions (or simply fall back to a more basic approach where necessary).

The ultimate goal of this document then is to introduce developers to the most fundamental way to build Sun ONE Application Framework applications, so they become familiar with Sun ONE Application Framework's interactions with applications built on top of the framework, and more fluent in the Sun ONE Application Framework itself.

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Writing Sun ONE Application Framework Applications

Writing a Sun ONE Application Framework application consists of first laying out an application structure, and incrementally adding Sun ONE Application Framework objects to that structure. Although this can be done entirely by hand and from scratch, the task has been simplified by creating a Sun ONE Application Framework tools module for the Sun ONE Developer Studio that assists developers in writing their Sun ONE Application Framework applications. With the assistance of these tools, creating a Sun ONE Application Framework application becomes a simple process of generating Sun ONE Application Framework components using wizards, and customizing them to an application.

Before demonstrating the creation of a simple Sun ONE Application Framework application, you will cover the basics of how a Sun ONE Application Framework application is structured.

J2EE/Sun ONE Application Framework Terminology

There are terms in this document such as application, module, and components. These terms can be confusing, because they are also used in more general Web architecture and development discussions.

The following table contains a list of the most important terms found in this tutorial.

* Refer to the Java 2 Platform Enterprise Edition Specification v1.2 (J2EE) section J2EE8.1 for a detailed explanation of this term.

How Sun ONE Application Framework Applications Are Organized

The Sun ONE Application Framework provides formal application and module entities. A Sun ONE Application Framework application is a base Java package that contains one or more sub-packages (Sun ONE Application Framework modules). It is perfectly acceptable for an application to consist of only one module, and it is likely be the common situation for smaller applications. Each module inherits behavior from its parent application-level components, and might also customize this behavior separately from other modules.

In J2EE Web application container terms, a Sun ONE Application Framework application corresponds one-to-one with a servlet context, and thus is subject to the constraints enforced by the container for servlet contexts.

Before starting to develop your application, you should first decide how it should be organized:

• Determine which modules will be grouped together into your Sun ONE Application Framework application.

Avoid over-categorizing your application into several modules simply because the Sun ONE Application Framework provides this capability. In many cases, one module is sufficient.

• Decide on an application package name.

The application package name can be arbitrarily complex and will likely reflect your organization's packaging strategy. Each of your modules becomes a package beneath this application package.

• Assign a deployment-time or published Web application name.

In Apache Tomcat, the directory immediately beneath the /webapps directory would bear this name. In the Sun ONE Application Server, the directory immediately beneath the $instance_dir/applications/j2ee-modules directory would bear this name. The deployed application name is the same as the name WAR file name.

For example, if you have two Application Framework modules (named module1 and module2) that comprise a Sun ONE Application Framework application, you would call this application myapp. The full application package name would be com.mycompany.myapp.

• The application package would be com.mycompany.myapp
• The module1 package would be com.mycompany.myapp.module1
• The module2 package would be com.mycompany.myapp.module2

In general, the application package name should be different from that of any of its modules.

For example, your first instinct might be to name both your application and its primary module foo. This can easily lead to confusion for someone trying to understand your application and your application development tools. Instead, consider naming the application package something like fooapp, or calling the primary module something like main or module1. This makes your application structure much easier to understand, especially when you add to it in the future.

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About the Sun ONE Application Framework Tutorial

You will now develop a simple application so you can experience using the Sun ONE Application Framework and its tools. This application consists of two pages: a login page, and a customer account page, and demonstrates the following:

• Retrieving field values submitted by the user.
• Returning a status message to the user.
• Using a QueryModel to retrieve customer information.
• Using a QueryModel to update customer information.
• Coordinating user input with QueryModel SQL WHERE criteria.
• Moving from one page to another.
• Using a WebServiceModel to perform a Google Internet search.
• Displaying the multiple search results of a WebServiceModel.

This tutorial is divided into sections and tasks the steps required to develop the application. Each section addresses a broad topic, at the end of which you have an application that you can run.

Each task within a chapter is a relatively self-contained topic and contains several more detailed steps.

Sun ONE Application Framework Tutorial

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