Introduction

Suppose your company wants to sell products online. You have a database that gives the price and inventory status of each item. But, your database doesn't speak HTTP, the protocol that Web browsers use. Nor does it output HTML, the format Web browsers need. What can you do? Once users know what they want to buy, how do you gather that information? You want to customize your site for visitors ' preferences and interestshow? You want to keep track of user 's purchases as they shop at your sitewhat techniques are required to implement this behavior? When your Web site becomes popular, you might want to compress pages to reduce bandwidth. How can you do this without causing your site to fail for the 30% of visitors whose browsers don't support compression? In all these cases, you need a program to act as the intermediary between the browser and some server-side resource. This book is about using the Java platform for this type of program.

"Wait a second," you say. "Didn't you already write a book about that?" Well, yes. In May of 2000, Sun Microsystems Press and Prentice Hall released Marty's second book, Core Servlets and JavaServer Pages . It was successful beyond everyone's wildest expectations, selling approximately 100,000 copies, getting translated into Bulgarian, Chinese simplified script, Chinese traditional script, Czech, French, German, Hebrew, Japanese, Korean, Polish, Russian, and Spanish, and being chosen by Amazon.com as one of the top five computer programming books of 2001. Even better, Marty was swamped with requests for what he really likes doing: teaching training courses for developers in industry. Despite having to decline most of the requests, he was still able to teach servlet and JSP short courses in Australia, Canada, Japan, Puerto Rico, the Philippines, and at dozens of U.S. venues . What fun!

Since then, use of servlets and JSP has continued to grow at a phenomenal rate. The Java 2 Platform has become the technology of choice for developing e-commerce applications, dynamic Web sites, and Web-enabled applications and service. Servlets and JSP continue to be the foundation of this platformthey provide the link between Web clients and server-side applications. Virtually all major Web servers for Windows, Unix (including Linux), MacOS, VMS, and mainframe operating systems now support servlet and JSP technology either natively or by means of a plugin. With only a small amount of configuration, you can run servlets and JSP in Microsoft IIS, the Apache Web Server, IBM WebSphere, BEA WebLogic, Oracle9i AS, and dozens of other servers. Performance of both commercial and open -source servlet and JSP engines has improved significantly.

However, the field continues to evolve rapidly . For example:

• The official servlet and JSP reference implementation is no longer developed by Sun. Instead, it is Apache Tomcat, an open-source product developed by a team from many different organizations. So, we provide great detail on Tomcat configuration and usage.

• Except for Tomcat, the servers popular when the book was first released are no longer widely used. So, we cover Macromedia JRun and Caucho Resin instead.

• Version 2.4 of the servlet specification was released in late 2003. Many APIs have been added or have changed. So, we have upgraded the book to be consistent with these APIs.

• Version 2.0 of the JSP specification was released (also late 2003). This version lets you use a shorthand expression language to access bean properties and collection elements. So, we cover both "classic" scripting and use of the JSP 2.0 expression language.

• Two new versions of JDBC have been released, providing many useful new features. So, we explain database access in the context of these new features.

• MySQL has emerged as a popular free database. So, we explain how to download, configure, and use MySQL (we also cover Oracle9i and Microsoft Access, of course).

Whew. Lots of action in the server-side Java community. Yup; and to reflect this fact, the book has been completely and totally rewritten from top to bottom. Many new capabilities are now covered. Experienced developer Larry Brown was brought in to add his expertise, especially in database applications. Many hard-learned lessons are explained in detail. Many techniques are now approached differently.

The new version provides a thorough and up-to-date introduction to servlet and JSP programming. We hope you find it useful.