Programming Jakarta Struts, Second Edition

JSP Model 1 and Model 2 Architectures

The early JSP specifications presented two approaches for building web applications using JSP technology. These two approaches were the JSP Model 1 and Model 2 architectures. Although these terms are no longer used in the JSP specification, they still are widely used throughout the web tier development community.

The two JSP architectures differ in several key areas. The major difference is in how and by which component the processing of a request is handled. With the Model 1 architecture, the JSP page handles all of the processing of the request and is responsible for displaying the output to the client. This is illustrated in Figure 1-3.

Figure 1-3. JSP Model 1 architecture

Notice that there is no servlet involved in the process. The client request is sent directly to a JSP page, which may communicate with JavaBeans or other services, but ultimately the JSP page selects the next page for the client. The next view is determined based on either the JSP selected or parameters within the client’s request.

In contrast, in the Model 2 architecture, the client request is first intercepted by a servlet, commonly referred to as a controller servlet. This servlet handles the initial processing of the request and determines which JSP page to display next. This approach is illustrated in Figure 1-4.

Figure 1-4. JSP Model 2 architecture

As shown in the figure, ...