I am playing around with JSP, so I installed Tomcat. I am seeing a lot of ads for IBM's WebSphere. I am also looking into ColdFusion, and on Adobe.com, they are promoting JRun. I decided to look up application servers and found a lot for Java, but some require Tomcat. I thought application servers did all the language-specific stuff and then the webserver would display website. If the application server did the execution of the scripts, why couldn't I use Apache or any webserver instead of one that could do JSP pages by itself?
I also found a lot of things that were frameworks. What's the difference between application servers and frameworks?
If I want to write JSP scripts, would something like JRun, WebSphere, GlassFIsh, or JBoss be a replacement for Tomcat, or do I not understand the purpose of an application server?
If I had a server that already had Apache and Tomcat installed, in order to run other languages, could I just install:
IgniteFusion - ColdFusion
Mono - .Net
Ruby - Ruby On Rails
WebWare - Python
CServer Pages - C++