Chapter 37. Mistake: Alternative Flow as Extension

Fault

Modeling an alternative flow of a use case as an extension of that use case.

Keywords: Addition to flow, alternative flow, extend relationship, extracting flow.

Incorrect Model

Model

Model

Detection

A clear sign of this modeling mistake is when the flow of an extension use case is supposed to replace a part of the base use case flow. Another indicator is, of course, that the base use case is not complete without the extension, because it lacks an alternative flow.

Discussion

A use case has one flow, or sometimes multiple flows, considered to be the normal or basic flow of that use case. This flow will be ...

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