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Let's say I have three use cases:

First and second use cases are simple actions that can't be performed simultaneously. The third, though, can only happen while first OR second has happened. Do I have to specify this in the model below? If yes, how? The model right now gives me impression that the first and second use cases have to be performed BOTH(which is not true in the system) in order to perform the third.

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Michal
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1 Answers1

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Try to model it using a precondition: "The precondition of a use case announces what the system will ensure is true before letting the use case start". (A. Cockburn, Writing Effective Use Cases, p. 81)

Exactly how you can annotate a precondition depends on your tool. A precondition is typically written down in textual form (human-readable to non-IT stakeholders) or explicitly references another use case.

Advantage: Clean solution. Uncluttered diagram. Possible disadvantage: You'll only see that in the full documentation. Possible workaround: Define such if/else related decisions in an activity diagram and refer to that in the use cases with a note / hyperlink.

observer
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  • I have re-modeled the use case to have `extend` instead of `include`, but this solution looks good too! – Michal Jan 29 '13 at 15:11