This extension is primarily about writing a Java Servlet. The extension is primarily for students who has followed the course Web Programming or has basic skills in html.
A Java Servlet is a program, which is run on a server for homepages. The main idea is, that when a browser asks for a given homepage, the server of the homepage calls the servlet. The servlet then creates a homepage, which is returned to the browser.
The following links contains usefull informations about servlets:
You can be inspired by the way google works when creating your servlet.