Java and XSLT

Beyond Dynamic Web Pages

You probably know a little bit about servlets already. Essentially, they are Java classes that run on the web tier, offering a high-performance, portable alternative to CGI scripts. Java servlets are great for extracting data from a database and then generating XHTML for the browser. They are also good for validating HTTP POST or GET requests from browsers, allowing people to fill out job applications or order books online. But more powerful techniques are required when you create web applications instead of simple web sites.

Web Development Challenges

When compared to GUI applications based on Swing or AWT, developing for the Web can be much more difficult. Most of the difficulties you will encounter can be traced to one of the following:

• Hypertext Transfer Protocol (HTTP)

• HTML limitations

• browser compatibility problems

• concurrency issues

HTTP is a fairly simple protocol that enables a client to communicate with a server. Web browsers almost always use HTTP to communicate with web servers, although they may use other protocols such as HTTPS for secure connections or even FTP for file downloads. HTTP is a request/response protocol, and the browser must initiate the request. Each time you click on a hyperlink, your browser issues a new request to a web server. The server processes the request and sends a response, thus finishing the exchange.

This request/response cycle is easy to understand but makes it tedious to develop an application that maintains state ...