A few years ago, the hype surrounding applets put Java on the map as a programming language for the Web. Today, Java servlets stand poised to take Java to the next level as a Web development language. The main reason is that servlets offer a fast, powerful, portable replacement for CGI scripts.
The Java Servlet API, introduced as the first standard extension to Java, provides a generic mechanism to extend the functionality of any kind of server. Servlets are most commonly used, however, to extend Web servers, performing tasks traditionally handled by CGI programs. Web servers that can support servlets include: Apache, Netscape's FastTrack and Enterprise Servers, Microsoft's IIS, O'Reilly's WebSite, and JavaSoft's Java Web Server.
The beauty of servlets is that they execute within the Web server's process space and they persist between invocations. This gives servlets tremendous performance benefits over CGI programs. Yet because they're written in Java, servlets are far less likely to crash a Web server than a C-based NSAPI or ISAPI extension. Servlets have full access to the various Java APIs and to third-party component classes, making them ideal for use in communicating with applets, databases, and RMI servers. Plus, servlets are portable between operating systems and between servers -- with servlets you can "write once, serve everywhere."
Java Servlet Programming covers everything you need to know to write effective servlets and includes numerous examples that you can use as the basis for your own servlets. The book explains the servlet life cycle, showing how you can use servlets to maintain state information effortlessly. It also describes how to serve dynamic Web content, including both HTML pages and multimedia data. Finally, it explores more advanced topics like integrated session tracking, efficient database connectivity using JDBC, applet-servlet communication, inter-servlet communication, and internationalization.