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Use cases question.

Tonny Tssagovic
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Joined: Dec 30, 2003
Posts: 226
Hello folks,
I have a question concerning use cases. I have seen that some people write only the user actions, and the system's reply (with the argument that requirements are defined from the view point of the actor), while others write the steps involved to "calculate" the reply, since the system usually requires several steps before generating the reply. (Both are from "professional people")-
What is the standard way of doing it? I just want to have use cases in a school report and I would include the sequence diagram showing how the different objects in the system interact to solve the problem.
Thanks you!
Ilja Preuss
author
Sheriff

Joined: Jul 11, 2001
Posts: 14112
Moving to the Process forum...


The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
Ilja Preuss
author
Sheriff

Joined: Jul 11, 2001
Posts: 14112
Originally posted by Tonny Tssagovic:
What is the standard way of doing it?

There is no standard way, because every project and every team has different needs. What formatlity you need depends on many things: what you are doing them for, on colaboration constraints, risk of the project etc.
For some teams, a couple of words on an index card is all they need. Others feel they need to write pages of formal descriptions.
Stan James
(instanceof Sidekick)
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Joined: Jan 29, 2003
Posts: 8791
Sometimes you'll see a use case step reference other documents like a "business rules repository." You might see something like this:
user selects "calculate total"
system calculates total (See BR1234 for calculation rules)
system displays total
This is a neat way to keep your use case at a "consistent level of abstraction" and that's one of my criteria for easy communication in documents, code, IRS forms, etc.


A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi
Scott Ambler
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Joined: Dec 12, 2003
Posts: 608
You might find the examples posted at http://www.agilemodeling.com/artifacts/essentialUseCase.htm and http://www.agilemodeling.com/artifacts/systemUseCase.htm to be of help. These pages include both simple and complex versions of use cases. The goal should be to model just enough to be sufficient for your task at hand -- any extra work would be a waste of time.
- Scott


<a href="http://www-306.ibm.com/software/rational/bios/ambler.html" target="_blank" rel="nofollow">Scott W. Ambler</a><br />Practice Leader Agile Development, IBM Rational<br /> <br />Now available: <a href="http://www.ambysoft.com/books/refactoringDatabases.html" target="_blank" rel="nofollow">Refactoring Databases: Evolutionary Database Design</a>
Ilja Preuss
author
Sheriff

Joined: Jul 11, 2001
Posts: 14112
Originally posted by Scott Ambler:
The goal should be to model just enough to be sufficient for your task at hand -- any extra work would be a waste of time.

Well, the problem probably is that the "task at hand" is "pleasing the teacher"...
Jeff Langr
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Joined: May 14, 2003
Posts: 762
I don't think anyone answered the original question.
What appears to be the most commonly accepted narrative form for use cases is one that is in the form of "the user does this; then the [application] does this." For example, "the clerk scans an item; the POS station displays the scanned item name and price." Use cases answer the question, "How does the user interact with the system?" By only supplying the user actions, you would only be presenting half of the story.
Be careful not to supply implementation details in the use case document.
-Jeff-
[ March 04, 2004: Message edited by: Jeff Langr ]

Books: Agile Java, Modern C++ Programming with TDD, Essential Java Style, Agile in a Flash. Contributor, Clean Code.
Tonny Tssagovic
Ranch Hand

Joined: Dec 30, 2003
Posts: 226
Thank you all for your time: Ilja, Stan, Scott and Jeff;I appreciate it.
The problem as Ilja said is there are no real "requirements" but to please the teacher.
 
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subject: Use cases question.