Consider a frame page with an applet that contains a JTree and the other page is a normal HTML form page. Now if a user enters some data on the normal html page and submits it(to a servlet) how can that be reflected on the applet. In case of JTree add a node. From an applet we first have to make the contact to the servlet and then the servlet can do some processing and then the data can be send back. BUT how is it possible to do some processing in a servlet(called from an HTML page) and then send it to an applet.