Actually it isn't trivial for java webservers. Only root processes are allowed to use a port <=1024 by default, so you can't just change a config line in tomca

Actually it isn't trivial for java webservers. Only root processes are allowed to use a port <=1024 by default, so you can't just change a config line in tomcat/jboss/jetty and have it work automatically. You would have to then start/run the app as root, which is a Bad Idea, or mess with getting the OS to allow you to use a lower port. The safest solution then is to have something in front that is allowed on port 80 and setup forwarding to 8080.