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.
This book is a superb introduction to Java servlets and their various communications mechanisms. It includes deep and comprehensive coverage of the Java Servlet API, and also of HTTP, non-HTTP socket communications, Remote Method Invocation (RMI) and more. Throughout, the authors present excellent illustrative code and go to much effort to explain why things work the way they do.
The authors (to their credit) do not assume that Java programmers will be familiar with transport protocols or what really goes on when a Web server operates. They begin by showing how to use servlets to generate static pages, then show how to get servlets to generate customised documents in response to requests from the client side. That alone will satisfy many readers' problems. However, the authors go on to tell how to track sessions with servlets, how to carry out secure transactions, how to get servlet threads to communicate with each other, and more. If it can be done with Java servlets, it's discussed in this book. Java Servlet Programming also includes a reference to the Java Servlet API, version 2. --David Wall
