The requested resource (/Servets/a.html) is not available.
You Might be going wrong because in the form action of your html you have entered some wrong URL.
Ideally the URL should be like <form method="POST" action="http://localhost:8080/<WEB_APPLICATION_NAME>/SERVLET_NAME>
Here 8080 is the port on which tomcat is deployed.
Also make sure that you have made the correct entries in your web.xml file for the corresponding SERVLET_NAME. There are some tags like <servlet-name>,<servlet-class> and <url-pattern> for which you need to enter some data corrresponding to your servlet.
How does html - the static page description language - call a servlet? If you mean it has links to servlet resources, that error indicates that the html is never loaded so whever servlet is never called. Your use of "Servlet" in the URL suggests you may be relying on the dreaded Invoker servlet syntax. Not a good idea. Bill [ June 04, 2008: Message edited by: William Brogden ]