hoffmandirt

Can someone explain to me how the generalization and extends purposes differ in a UML Use Case Diagram? It seems like the both describe inheritance.

InfoGeek

I don't think generalizations and extends etc. relationships are shown in a Use Case diagram. These are shown in the class diagrams.
Here's a little tutorial on UML Use Case Diagrams.

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hoffmandirt

Did you look through that? That tutorial shows the use of the extends arrow, but not the generalization arrow. I think that the extends arrow basically says that I can use any one of the options that extends the use case, and the use case itself. Whereas a generalization arrow says that the use case is a base case for the use cases inheriting from it and that I must choose one of the ones that inherit the base case.

Seif

A specialisation/Generalisation relationships are similar to Class diagrams where a Super use case represents common properties of its sub use case.
An extend relationship is usually used to deal with further explicit interactions, or with exceptional cases that normally does'nt occur.

They are both forms of generalisation, and are both poorly defined in UML. Depending on the situation, it can be argued which is more appropriate.

InfoGeek

My bad. When I read generalization and extends(or inheritance), I thought about inheritance of classes and not use cases. Sorry for that.

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