There are any number of ways: HTTP (which might be easiest), shared files, web service, JMS, Email, shared DB, TCP/IP, ...
Direct access to objects or sessions in another web app can be enabled on some servlet engines, but is server-specific. For Tomcat, have a look at the crossContext attribute of the Context. It enables the use of RequestDispatchers across web apps. [ August 24, 2006: Message edited by: Ulf Dittmer ]
Thanks for your reply. Do Tomcat only provides the way? Servlet technology is not having any approach to this. Suppose if two webapps are running in the same webserver or two webapps are running in differnet servers do i will have to go for some other mechanism?
If you can elaborate your answer more i would be very thankful to you.