Articles : JavaServer Faces, Web Applications Made Easier :

JavaServer Faces, Web Applications Made Easier

By Mike Houghton

Introduction

The Java Community Process (JCP), in an effort to keep Java in the forefront of Web Applications, has come up with a specification called JavaServer Faces (JSF), which attempts to standardize the way we develop Java Web applications and provides a set of rich ready-to-use UI components. In this article, I'll try to discuss the JSF technology, what's wrong, what's right and why it's necessary.

Lets start by taking a look at what JavaServer Faces is and what it can do for you.

Getting Started

To begin, JavaServer Faces (JSF), also known as JavaServer Release 127 (JSR 127) is a user interface framework designed to aid in building Java-based web applications. These applications will run on the server side of the process and will render the user interface side back to the client. The client interface portion runs on the server and not the client and yet JSF responds to events generated on the client side.

You can think of JSF as a combination of Struts (an open source JSP-based framework application) and Swing (the standard Java framework application). However JSF is not a replacement for Struts or Swing. In fact JSF has been designed to work quite well with both.

Below is a quick summary of the six main areas that JSF either improves on or now offers for Java developers:

1. It will allow developers to create user interfaces from a set of standard, reusable server-side components.
2. It provides a set of JSP tags to access server-side components.
3. It encapsulates event handling and component rendering so that developers can use standard JSF components or custom components that support markup languages other than HTML such as Norpath or XWT.
4. It transparently saves the state information and repopulates the forms when they redisplay.
5. It now allows tool vendors to develop IDEs for a more standard Web application framework.
6. It also provides the framework for implementing custom components.

JSF is very efficient, handling HTTP requests in only seven distinct phases. To help understand the flow of information, take a look at the chart below.

The process of control is shown with solid lines and the dashed lines show the alternate flow allowing for a page redisplay and validation request or in the event of a conversion error.

There are several other components involved, however these are the key elements to this process. As you can see, what makes it different from other servlet/JSP applications is that JSF has an event-driven nature versus being JSP-centric. This is an important characteristic of a JSF application.

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