can one use case be EXTENDed from more than one base use case?

Question

I have this use case, suppose named A, which is in nature an extension of both use cases B and C. Is there a standard way to illustrate this?

For example is this true?

example

score 1 · Answer 1 · answered Apr 15 '13 at 17:40

1

In UML, you can have an extension of several main use cases at a time without problem.

As for the link you provide, I'd connect the actor to B and C instead of A, because B and C are the "main" use cases. The actor that launches A is the actor that performs the main use case. In this way you could even have a different actor for B and C, and naturally A would be done by one or the other depending on the main use case.

answered Apr 15 '13 at 17:40

Steph

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I'm a little confused here (mainly because of my own naming use case A, B, and C)! I have an use case (Action A) in my software witch is special case (extended) of doing tow other use cases (both Actions B and C), how should I illustrate it? – Ho'jat Kaveh Apr 18 '13 at 10:04

score 0 · Answer 2 · answered Apr 16 '13 at 23:01

A use case extends 0..* use cases, and is extended by 0..* use cases, but note that the arrow is drawn from the extending use case to the extended use case. In your diagram there is a single base (extended) use case, namely A.

An extend relationship between use cases is shown by a dashed arrow with an open arrowhead from the use case providing the extension to the base use case [UML/2.4.1/Superstructure§16.3.3].

can one use case be EXTENDed from more than one base use case?

2 Answers2