When you compare application servers, you are just comparing J2EE implementations and if all you need is a J2EE implementation then you can probably use an open source application server. But BEA's customers need much more than that. The J2EE implementation is just the "surface" of an application server.
Once you start a J2EE development project, the application server you use will determine how fast you can do your edit-compile-debug cycle. It will determine how easy it is to move you J2EE application from development to staging to production. Once you need to deploy, operate and maintain your J2EE application, your J2EE application server plays an even bigger role. It determines how easy it is to update the application, how easy it is to scale up and down (if possible at all), and it determines how much visibility you have into the operation of your application.

All of these things add up to much more than the cost of just writing the code. In fact, the costs of maintaining application lifecycle and of managing a runtime environment easily dwarves the costs of the software you are using.

Taken from http://indicthreads.com/content/view/228/0/1/3/

¶ 9:57 am