JavaServer Faces Technology Benefits

One of the greatest advantages of JavaServer Faces technology is that it offers a clean separation between behavior and presentation. Web applications that are built using JSP technology, achieve this separation partially.

However, a JSP application cannot map HTTP requests to component-specific event handling nor manage UI elements as stateful objects on the server, which a JavaServer Faces application can. JavaServer Faces technology allows you to build web applications that implement the finer-grained separation of behavior and presentation that is traditionally offered by client-side UI architectures.

The separation of logic from presentation also allows each member of a web application development team to focus on a single piece of the development process, and it provides a simple programming model to link the pieces. For example, page authors with no programming expertise can use JavaServer Faces technology UI component tags to link to server-side objects from within a web page without writing any scripts.

Another important goal of JavaServer Faces technology is to leverage familiar UI-component and web-tier concepts without limiting you to a particular scripting technology or markup language. JavaServer Faces technology APIs are layered directly on top of the Servlet API, as shown in Figure 3-2.

This layering of APIs enables several important application use cases, such as using different presentation technologies, creating your own custom components directly from the component classes, and generating output for various client devices.

The concept of View Declaration Language (VDL), introduced in JavaServer Faces 2.0, allows UI components to be declared and presented by Facelets as well as JSP.

Facelets technology, available as part of JavaServer Faces 2.0, is built specifically for JavaServer Faces. It is now the preferred technology for building JavaServer Faces based web applications and offers several advantages over using JSP technology. Facelets technology is discussed in more detail in the next chapter.

Most importantly, JavaServer Faces technology provides a rich architecture for managing component state, processing component data, validating user input, and handling events.