Does anybody know how to deploy an updated war file and switching to it without stopping the server. All the requests from application users has to be carried out during this process.?? I am waiting for some response !!!
If you really need that capability, you might need to look into clustering.
If your web app was deployed with a war file in the webapps directory, simply replacing the war file will cause Tomcat to redeploy the app but, depending on the OS and how Tomcat was started, the cleanliness of this will vary. By cleanliness I mean that sometimes a windows service might have a jar file locked so it won't get overridden. Often (and I'm not sure why) some JSPs won't get overridden either. It may have to do with the file dates.
Upgrading this way is the equivalent to unzipping one directory structure on top of another. Things don't removed, only added, and sometimes overritten. Personally, I prefer a clean undeploy and then a new deployment with the current version but, our customers don't need 24/7 coverage.