Java based web application need to be deployed on application server such as Tomcat, WebSphere, etc. But in the real production environment of the customer, the port of these application server will not be exposed normally. So that a http server is needed to be set in front of application servers. Here are some solutions:
1. use Apache as a reverse proxy
2. use Application Request Routing & URL Rewrite components provided in IIS 7.5
3. If the application server is WebSphere 7.0, a plugin called iisWASPlugin will be provided to integrate IIS7.5 with WAS 7.0
After deploying your web application in this way, all the requests will be sent to port 80 at first, and then they will be for forwarded to backend application servers.