How can an applet communicate with a servlet?
Some classes to look at on the applet side are URL (particularly its getContent method) for simple access, and URLConnection and HttpURLConnection if you need more control over the connection. This article explains how to set and receive cookies when communicating with a web server. It is possible to transfer Java objects through serialization. A simple example is at http://www.frank-buss.de/echoservlet/ An introduction on how to use RMI in applets via HTTP tunneling can be found in this article.
