One reason why I don�t personally like this architecture is because it might impact your application�s performances pretty badly. To be more precisely I�ll tell you that separating the web app and ejb container (and having separate war and ear) will make impossible for your servlets or jsp to access the ejbs via their local interfaces. Therefore every client call will result in at least one remote call form the presentation layer to the business layer. Therefore one needs to design the application using kind of command design pattern strategy in order to reduce the number of calls from one layer to another. This will tide the application design to the system architecture as well. On the other hand this architecture provides very strong security capabilities. Even more this is exactly the kind of requirements that advocate the need of using an ejb container. So I suppose the answer is somewhere in between: if all deployed applications were initially designed for this kind of hardware architecture, it might be an excellent solution. However it might not be the most optimal configuration for deploying all type of applications. Regards.
I think, therefore I exist -- Rene Descartes
Joined: Dec 15, 2004
Hi Valentin I am facing the same problems and as an architect or solution designer we might need to justiy why this is ok and why not.I have got some points on this from net and would like to share with all
Reasons to add a web tier 1) Buffering stream input (data coming from the brower) - this is important for applications with different speed / quality client connections (e.g. dial-ups vs. DSL).
2) Buffering stream output (data going back to the browser) - this is even more important for applications with different speed / quality client connections - you don't want to waste a thread in your app tier waiting on data to get acked through a dialup connection.
3) Connection buffering and throttling (lots of incoming connections) - the handling for these conditions is often more efficient and more graceful in a web server; why waste your app tier resources handling this?
4) SSL - assuming you don't hardware accelerate it in your hardware load balancer, it's typically much more efficient to handle the SSL in the uber-scalable web tier than in the app tier.
5) Security - there can be a firewall between the web tier and the app tier, and a firewall in front of the web tier, and only one port (assuming no ssl) open in either firewall.
Are these valid and are there some more like this ?
subject: Why do we require a web server and an application server?