I'm currently starting a new app development. The app architect insists we use JBoss5 because its "better". Do anyone has a wider definition of "better" (if its the case)?
I have experience using Tomcat5 and 6 in large scale applications with big user loads and it handles pretty well (IMHO). Both would be running over a RedHat6 in identical hardware conditions (in case the implementation matters).
Thanks in advance
To say that any tool or framework is just 'better' is ridiculous. It always depends on the situation, architecture, etc. You don't necessarily want to use a hammer to drive a screw.
I wrote JBoss in Action, so I obviously like the JBoss technology, but I'll be the first to say that JBoss can be overkill in many situations. For example, for the last two sites I've developed, it made more sense to build with Grails and deploy on a standalone Tomcat instance.
Its a bit unfair to say that all you get when using JBoss is EJB and JMS. JBoss offers many services and features, including:
The thing that attracts many architects to JBoss is its flexibility. It uses a plugin architecture that allows you to add and remove services. As other have said, in uses Tomcat as its Servlet container, so you can literally whittle JBoss down to where it is practically just a Tomcat server. What is the benefit of doing this? Future proofing if you think that you're going to utilize other features of JBoss.
These services in JBoss come pre-integrated and strive to provide a consistent deployment model that minimizes your effort in writing application logic or configuration to integrate them yourself. That being said, other frameworks like Spring also do a great job of supporting a uniform ways of integrating many popular libraries and frameworks. But since they focus on integrating 3rd party libraries, the interoperability between services is up to you. Because JBoss is building the services and the integration platform, they spend time developing (and providing support) for interoperability.
Some questions to ask when making a choice are:
Not to sound like a shameless plug, but the first chapter of JBoss in Action is available for free on the Manning website. Though we don't do a direct comparison between JBoss and other applications servers and deployment environments in the chapter, we do talk about the architectural differences a bit, which is relevant to your question.