Component Diagrams - Part II related

[Sridhar Raman]

Hi,
I am looking for general inputs about Component Diagrams. I am kind of confused about what goes into Component Diagrams. The JSPs, Servlets, EJBs can all be mentioned in it and the dependencies between them can be shown. This seems too little for the 44 marks they are worth.
I find MVC is best shown in the Sequence Diagrams. I am wondering what kind of patterns and dependencies are usually shown in Component Diagrams? Is there a decent example of a component diagram of any system on the internet?

Thanks in advance
Sridhar

[Sean Walker]

I think Cade's component diagram is likely a good place to start. Although I was, and continue to be, quite unsure of what I seeing in them.
The strangest thing about Cade's diagram in my mind was that he had the JSPs dependent on the 'Order Controller'. I interpreted this controller to be a Front Controller - but thought this was strange since the JSP were dependent on it. The Front Controller pattern, as depicted in sequence and class diagrams in the various J2EE pattern books, should have the opposite relationship to this. That is the control is the first to receive request and it delegates them (usually intermediary classes) to various other classes including the JSPs (aka Views).
So I tried to come up with an interpretation of Cade's compnoent diagrams that would allow for that I said above. What I decided was that the links in Cade's component diagrams running from the views to the controler represent an indirect dependency 'through' the user. What I mean is, the JSP render pages that the users acts on cause HTTP requests to be forwarded to the control - in this sense the JSP pages are indirectly invoking the controler.
I'd loved to know what others think about this. I've asked before but didn't hear a peep from anyone...

[Sridhar Raman]

Thanks, Sean. I don't have a copy of Cade's book and haven't really planned on buying it. I have already made some headway with my design and am looking for inputs on very specific areas. Didn't feel it was worth paying for the entire book when I am going to be looking at only a few pages from it. Besides, having made some headway already with the assignment, I fear that learning a new approach may only end up contributing to my confusions.
Would you mind throwing a little light on the Component Diagrams from your understanding?
I don't know what the diagram looks like but based on what are talking about I understand that there is a dependency between the controller and the view. I can guess it to be one of two things.
(1) The FrontController incorporates the responsibilities of the dispatcher and/or helper components
(2) The PetStore talks of a Web Controller component(looks more like a helper to me) that sits between the FrontController and the JSP pages and talks to the JSP Pages. It could be a WebController. I tried to locate the diagram but couldn't remember where I saw it.

I guess you have already submitted your assignment and this shouldn't make much difference to you now, other than probably make you more anxious for the results
Regards
Sridhar

[Sridhar Raman]

I found the link for the WebController. It sends events to the EJBController and doesn't have anything to do with JSPs. I guess it boils down to the case of indirect reference or an overloaded FrontController.
http://java.sun.com/blueprints/guidelines/designing_enterprise_applications_2e/sample-app/sample-app1.3.1a3.html#wp1062293

Sridhar-