Chapter 3. The Presentation Layer
In this chapter, we will review the improvements in the Java EE platform for the
presentation layer. In concrete terms, we are going to talk about the following specific-
• Servlet 3.1
• Expression Language 3.0
• JavaServer Faces 2.2
The Servlet 3.1 Specification was developed under JSR 340. This section gives you
only an overview of improvements in the API. The complete document specification
(for more information) can be downloaded from http://jcp.org/aboutJava/communi-
What is a Servlet?
There was a time in computer science when we could not create dynamic web pages.
At that time, users had access only to static web pages, such as in a newspaper.
Among the many proposed solutions, the first Java solution was the Servlet , a revolu-
tionary technology used to extend the capabilities of servers based on the request-
response programming model. It enabled web servers to handle http requests and
dynamically generate web pages according to user parameters. Since then, techno-
logies have advanced a lot in order to facilitate the development of web applications.
However, the Servlet technology remains the most widely used Java solution for pro-
cessing of HTTP requests/responses in the background.
That said, at the base of almost all Java frameworks dedicated to the HTTP protocol
(JSF, Struts, Spring MVC, BIRT, web services solutions), you will find at least one
Servlet (that is, you have FacesServlet in JSF, ViewerServlet , and the
BirtEngineServlet for BIRT). You understand why this technology should attract
our attention, because a change in the Servlet specification will have repercussions
on a multitude of tools.