JavaServer Faces

JSP Processing

A JSP page is simply a regular web page combining static markup with JSP elements that generates the parts that differ between requests, as shown in Figure 4-7.

Figure 4-7. Template text and JSP elements

Everything in the page that isn’t a JSP element is called template text. Template text can be any text: HTML, WML, XML, or even plain text. When a JSP page request is processed, the static template text and the dynamic content generated by the JSP elements are merged, and the result is sent as the response to the browser.

A web container that supports JSP intercepts all requests for JSP pages. To process all JSP elements in the page, the container first turns the JSP page into a servlet (known as the JSP page implementation class). The conversion is pretty straightforward; all template text is converted to println( ) statements similar to the ones in the servlets shown in Example 4-1 and Example 4-2, and all JSP elements are converted to Java code that implements the corresponding dynamic behavior. The container then compiles the servlet class.

Converting the JSP page to a servlet and compiling the servlet form the translation phase. The JSP container initiates the translation phase for a page automatically when it receives the first request for the page. The translation phase takes a bit of time, so the first user to request a JSP page notices a slight delay. To avoid ...