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Servlets are server side Java classes that add functionality to a web server in a manner similar to the way applets add functionality to a browser. Servlets can be used as a replacement for CGI scripts (or ASP scripts) and they support the standard request/response computing model used by web servers. In this request/response model, a client sends a request message to a server and the server responds by sending back a reply message (usually as HTML). Servlets run on the web server platform as part of the same process as the web server itself. The web server is initializes, invokes, and destroys each servlet instance. The web server communicates with servlets via a simple interface: javax.servlet.Servlet. This interface defines three main methods: init() //invoked on servlet startup, put init code hereservice() //each client request invokes this method destroy() //put cleanup code here To write a servlet, you can simply extend the Servlet class and implement the three main methods. More commonly, however, you would extend the HttpServlet class which has http support built in, making it easy to access request and response objects. When you extend HttpServlet, you can write code for a doGet() and/or doPost() method. For more information on servlets, go to Sun Microsystem's servlet page Example 1: Design Your Own Webpage Servlet Example 3: mySQL Servlet (reads records from mySQL database)
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