Part 2: Sequence diagrams

[Vlad Eroshin]

How detailed the sequence diagrams should be. Do I need to put each object participating in particulare usecase? I tried to create one diagram and it grew up to 2200 pixels wide.

Please advise.

Thank you very much!

Vlad

[Ricardo Ferreira]

It will depende of how much details do you want to explicit at your diagrams. For a higher level design focus on initial architecture, you can depict your diagrams using only collaboration techniques. Note that you don't need to use collaboration diagrams for this, the collaboration techinique is about the emphasis on which responsability belongs to which object.

An example of collaboration could be an service locator object that get's the remote interface from the JNDI treee, and this service is colaborative with the business delegate object that needs this remote interface. An collaboration is just some service that an object could perform to help another object, and they provides those colaborative services for an biggest pourpose: An specific scenario of an use case.

For the assignment design pourposes, you must focus muchmore in collaboration rather than 'step-by-step' method calls. Remember: The architecture are created to be an guide for the system construction, by a developer perspective.

Best Regards!

[Vlad Eroshin]

Thank you very much, Ricardo!

[J Davidson]

It all depends on what, and to whom, you are trying to communicate. Putting too much details in a sequence diagram can only clutter things up and drown out the important parts. An average person can hold around 7 items in his short-term memory, so use that as your guideline on how many objects to include in a sequence diagram.

[Samuel Pessorrusso]

7 items is too short. My sequence has about 12 item and a lot of messages.

[Dan Drillich]

Hi Ricardo,

It will depende of how much details do you want to explicit at your diagrams. For a higher level design focus on initial architecture, you can depict your diagrams using only collaboration techniques. Note that you don't need to use collaboration diagrams for this, the collaboration techinique is about the emphasis on which responsability belongs to which object.

Thanks a lot for your advice!

I agree with you that the collaboration diagrams can bring more value than sequence diagrams at the architecture level. The collaboration diagram seems to me like a natural extension of the component diagram.

Regards,
Dan