Pro JSF and Ajax

The growing complexity of building applications creates a need for simplicity. So far, in
the J2EE realm, there has not been a clear choice of technology for Web applications. The
traditional application programming interfaces (APIs), such as JSP and servlets, do not really
provide enough abstraction from the underlying grunt work of implementing a multitier
application. To fulfill these requirements and to provide some level of simplicity, the industry
has evolved in a direction whereby open source communities and software companies are
providing application developers with frameworks to protect them from the complexity
introduced by multitier applications.
Tapestry, Struts, Tiles, TopLink, Hibernate, ADF UIX...
Many frameworks have the same underlying ideas but solve a problem a little differently
and in different layers of a multitier application (the view layer, the controller layer, and the
model layer). Examples of frameworks are Struts (an open source controller framework);
TopLink and Hibernate (model frameworks); and Tiles, Tapestry, XUL, and ADF UIX (so-
called view frameworks).
The benefits of application frameworks are the modularity, reusability, and inversion of
control (IoC) they provide to developers. By encapsulating implementation details, frame-
works enhance modularity and improve software quality by centralizing the impact of design
and implementation details. Thanks to the stable environment provided by frameworks, they
also enhance reusability by allowing developers to create generic components that can be
reused in new applications. This reuse of framework components improves application devel-
oper productivity and the quality of application software. By leveraging IoC, the framework
manages which application-specific methods are called in response to user events.
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Note
IoC means you have registered some part of your code with the framework, and the framework will
call this code when the client requests it. This is also referred to as the Hollywood principle. ("Don't call us.
We'll call you.")
In the previous retail software scenario (refer to Figure 1-1), frameworks can help increase
developer productivity and ease of maintenance, but the frameworks are also incompatible
with each other, which makes integration hard to handle. In contrast, JSF is a standard frame-
work that aims to solve incompatibility.
C H A P T E R 1
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T H E F O U N D AT I O N O F J S F : C O M P O N E N T S
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