I need to make an UC diagram for a project of mine, but I don't know when to use include or extend. My actor (a Professor) can choose one of his students and do some operations (ex: see his grades), now from the diagrams I saw, my see student's grades use case should include select student , but in my app you first need to select the student then choose the operation, should this mean see student's grade should extend select student?


1 Answer 1


"Selecting a student" is not really a first class use case on its own - this step alone is incomplete, in isolation it fulfills no purpose. As you wrote about your application, the selection is actually done for choosing another operation, and only the combination of both may become something which is a complete user task.

So the selection is only a fragment of a use case: it can be part of several other first-class use cases. As explained in this older SO Q&A, this means the "includes" relation will be the more appropriate choice.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.