Sequence diagram.

[Tonny Tssagovic]

Hello folks,
I wanted to ask you guys about sequence diagrams. Assuming u r a consultant and have to deliver all the docs.
How detailed are the sequence diagrams in genral? Should you include stuff like the DAO and its Factory and the DB? Does the sequence diagram inculde all the paths (and how do you deal with it in case it has 5 dif. paths all with more then 8 method calls.
Any help will be appreciated.

[Sridhar Raman]

It depends on what you want to show in your Sequence Diagrams and at what level you are modeling. I like to show MVC interactions in my sequence diagrams. DAO, Factory can be shown in sequence diagrams depending on whether you want to show *something happening* or just a static relationship between components, in which case you could show it in your component diagram.
Sequence diagrams are not the best places to show multiple paths that are based on certain decisions. Though it is legitimate to use decision symbols and loops in Sequence Diagrams, it is not generally advisable because it would hamper the readability of the diagram. These are best shown in Activity diagrams. However, if you *must* show these multiple paths in Sequence diagrams, you could do one of two things.
1. Use more than one sequence diagram to illustrate the various paths
2. Add notes to the model briefly stating about the alternative paths where appropriate.

regards
Sridhar

[Tonny Tssagovic]

Thanks Sridhar,
Well, just another question, do you usually have a sequence diagram /use case, and a session bean for the flow of your sequence diagram? Doesn't this usually end up in ONE FONCTION / Session bean (session facade, hiding the flow of events used in the use case?
Any help will be appreciated"
Thanks in advance

[Sridhar Raman]

Hi Tonny,
That's right, in most cases you would end up with a Session Facade at the end of the message sequence. However, you could have multiple calls to the Facade and this depends on the number of message sequences in the flow you are trying to depict. You could also choose to drill down further and show other components that support the Session Facade.
Sridhar-

[Tonny Tssagovic]

I did not fully get what you said, but thanks anyway.. I might understand it when I become older