Thanks for the clarifications was not aware of the thing called InvokerServlet.
I need couple of more inputs w.r.t this.
1) Is this InvokerServlet part of Servlet 2.3\2.4 Specification
2) Is it something specific to Tomcat (The servlets are getting invoked in Websphere also.).
3) Where exactly is this InvokerServlet mapping is done (any standard xml file read by Web Containers).
1. No - it was supposed to be a way for beginners to experiment rapidly without having to work with web.xml - turned out to have disastrous consequences when people tried to use it for serious work.
2. apparently not
3. see the "default" web.xml in the tomcat conf directory where it is commented out - tomcat5.5.9