RE: (ROSE) Use Cases scenarios - newbie question

[Arne G. Styve]

Hi Egor,

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Egor Shokurov
Sent: 29. november 2000 13:13
To: [EMAIL PROTECTED]
Subject: (ROSE) Use Cases scenarios - newbie question

Hello

 

We've just started using Use Cases to document/design our project.

 

What I can't get is how to define scenarios ( ie sequence of actions )

on Use Case diagram. Is there any standard way to do that or I just

need to put all this into documentation ? Or draw additional activity

diagram ?

 

Personally I prefere to use activitydiagrams to show "scenarios" at the Use-Case level. The Use-Case is the Requirement part of your process, and should describe WHAT and not HOW. Hence I've found sequence diagrams to be of little or no use.

 

For example the Use Case "Distribute a survey" should include

"Enter list of emails", "Enter start/stop dates" etc. etc. done in the

exactly same sequence. If any of steps fails, whole Use Case fails.

That's too simple sequence for activity diagram  

 

Why is it too simple ? In my oppinion, keeping it simple is just what it's all about. An activity diagram is just as good with 2 activities on it as with 10. (probably even better.....)

 

 and too long for

documentation. I tried to add one more dependency stereotype

"follows" - but it makes diagram overloaded.

 

NO, a Use Case is not suppose to show the sequence of actions. It is suppose to give an overview or a clear view of the functionality/services the system is to provide to the actors (users or other external systems). Hence the only associations/dependencies to depict in a Use-Case diagram are thos that show wether or not some function of the system is a spesialization or generalization of some other function, or if there are functionality thet are used in several use-cases (the <<uses>> dependency).

 

Please if you have any solution for this, post it here as it can be useful

for all use case novices.

 

Hope this gave you some answers to your questions. By the way, do you have access to RUP ? RUP has a pretty good description of what a Use-Case should describe, and how the Use-case diagrams could look like.

 

Arne

 

Thanks in advance

 

Egor A. Shokurov

Netreflector.com Inc.