is it possible to install more than one java application server on one server or VPS ? i want to install JBOSS , TOMCAT , WEBLOGIC and my be more. how this is possible and what the benefits and disadvantages ?!
It is possible, if you want to try all of them. You just have to select different port for each services.
Is there a real use-case ? You could have an application bound to your application server, and you could want to run different applications.