Chapter 24. Web Applications

CHAPTER GOALS

  • To understand the web application concept

  • To learn the syntactical elements of the JavaServer Faces web application framework

  • To learn about navigation in web applications

  • To build three-tier web applications

Web applications are a new type of software that has become very important in recent years. Applications for a wide variety of purposes, such as e-mail, banking, shopping, and playing games, run on servers and interact with users through a web browser. Developing web-based user interfaces is more complex and challenging than writing graphical user interfaces. Until recently, only primitive technologies (such as Java servlets) were available for this purpose. Fortunately, more capable frameworks for web programming have emerged that are roughly analogous to the Swing framework for client-side user interface programming. In this chapter, you will learn how to write web applications using the JavaServer Faces (JSF) framework.

The Architecture of a Web Application

A web application is an application whose user interface is displayed in a web browser. The application program resides on the web server. The user fills out form elements and clicks on buttons and links. The user inputs are transmitted over the Internet to the server, and the server program updates the web page that the user sees (see Figure 1).

The browser sends information to the server using the HTTP protocol that was described in Sections 21.2 and 21.5. The server responds by sending ...

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