Programming Jakarta Struts, 2nd Edition [Electronic resources] نسخه متنی

7.6 Looking Ahead to JavaServer Faces

JavaServer
Faces (JSF) is designed to provide a standard set of JSP tags and
Java classes that will make it easier to build Java server
application GUIs. One of the problems that JSF is trying to address
is that the Servlet and JSP technologies don't
provide specific enough APIs for creating the client GUI, and
developers have to rely on HTML components and one of several
alternatives to facilitate style and behavioral changes to all of the
views. The mechanism to manage all of this eventually takes on a life
of its own and overshadows the business of the application. Instead
of performing maintenance on business operations and logic, more and
more time is needed to manage the presentation controls.

JSF plans to fix this by creating a standard way to define complex
HTML forms and other GUI elements. This will enable developers to
focus their attention on a single component framework.

The first release of the framework includes the following design
goals:

1. Create a standard GUI component framework, which can be leveraged by
   development tools to make it easier for tool users to both create
   high-quality GUIs and manage the GUIs' connections
   to application behavior.

2. Define a set of simple, lightweight Java base classes for GUI
   components, component state, and input events. These classes will
   address GUI lifecycle issues, notably managing a
   component's persistent state for the lifetime of its
   page.

3. Provide a set of common GUI components, including the standard HTML
   form input elements. These components will be derived from the simple
   set of base classes (outlined in #2) that can be used to define new
   components.

4. Provide a JavaBeans model for dispatching events from client-side GUI
   controls to server- side application behavior.

5. Define APIs for input validation, including support for client-side
   validation.

6. Specify a model for internationalization and localization of the GUI.

7. Automate the generation of appropriate output for the target client,
   taking into account all available client configuration data (browser
   version, etc.).

8. Automate the generation of output containing required hooks for
   supporting accessibility.

7.6.1 What Does JSF Have to Do with Struts?

JSF and Struts should fit together quite well, and developers
eventually will be able to supplement or substitute the Struts custom
tag libraries with JSF components. The rest of the Struts framework
(both model and controller components) will remain relatively
unaffected by the JSF architecture.

JSF also will include an event model, but the architecture will be designed so that developers can choose to use the GUI components with or without the event mechanism.

Because there currently is no final public specification for JSF,
it's hard to be specific on exactly how the two will
tie into each other. However, Craig McClanahan, the founder of the
Struts framework, is now also one of the specification leads for the
JSF JSR. We can look closely at Craig's comments on
JSF and Struts and know that he is speaking with subject-matter
expertise. In fact, Struts 1.1 ships with an early look at how the
two might fit together. If you look in the
contrib folder under the Struts binary
installation, you will find a directory named
struts-faces. This directory contains a library
which supports the use of JSF in a Struts-based application. There
are also a couple examples that you can actually run in a container
and see JSF work first hand. For more information on this library and
JSF in general, see Chapter 18. You can find the
JSF JSR online at
http://jcp.org/jsr/detail/127.jsp.