Hi,

I'm really looking for some advice. I am used to the concept of extracting common behaviour that occurs in the main flows of multiple use cases, and turning that common behaviour into an included use case to avoid duplication of effort.

In a current project I have about 5 use cases where in the alternate flows it's validating the users authority level to ensure they are able to perform the behaviour in that alt flow.

In this particular example the user is requesting to perform an action outside the normal flow that requires increased user authority. the system needs to check their permissions, and where they are not high enough stop the user performing the action, and then create a task for someone with the correct authority to resolve.

I can't add the check as a precondition of the use cases, because it only occurs if the alternative flow is initiated. My understadning of Inlcuded use cases is that they can only be called from the main flow of the calling use case? Forgive me if my understanding is incorrect. I would welcome any advice.

Logc tells me that there must be a way to specify this piece of behaviour once.

Regards

Pete

You cannot use the <include> relation in this case. As the UML specification states: "Note that the included use case is not optional, and is always required for the including use case to execute correctly."

Source: http://www.omg.org/technology/documents/modeling_spec_catalog.htm#UML

My idea would be to use <extend> relation between the 2 use cases and add an extension point with a condition.

Example:

Online Help Use Case <extends> Perform ITM Transaction use Case

Extension point: Selection

Condition: Customer selected HELP

As a conlusion, I think it's ok to apply it in your situation