The JSP specification is based on the Java servlet specification. In fact, JSP pages are often combined with servlets in the same application. In this section, we first take a brief look at what a servlet is, and then discuss the concepts shared by servlets and JSP pages. In Chapter 3, we’ll take a closer look at how JSP pages are actually turned into servlets automatically.
If you’re already familiar with servlets, this is old news. You can safely skip the rest of this chapter.
In simple terms, a servlet is a piece of code that adds new functionality to a server (typically a web server), just like CGI and proprietary server extensions such as NSAPI and ISAPI. But compared to other technologies, servlets have a number of advantages:
All the major web servers and application servers support servlets, so a servlet-based solution doesn’t tie you to one specific vendor. And, since servlets are written in the Java programming language, they can be used on any operating system with a Java runtime environment.
Servlets are developed in Java and can therefore take advantage of all other Java technologies, such as JDBC for database access, JNDI for directory access, RMI for remote resource access, etc. Starting with Version 2.2, the servlet specification is part of the Java 2 Enterprise Edition (J2EE), making servlets an important ingredient of any large-scale enterprise application, with formalized ...