Use case diagram for role based list filter

Question

I have to model a use case diagram with the following requirements:

We have 3 actors (Actor1, Actor2, Actor3). All actors can view a list. The list must be automatically filtered based on the actor. So for Actor1 Filter1 ist automatically applied to the list, for Actor2 Filter2 is applied and for Actor3 Filter3 ist applied.

I am not sure what the best practice is to model this scenario using a use case diagram.

Answer 1

You have basically 2 options.

1. Use one UC with eventually different scenarios (prefered in my opinion). In this case you have only 1 UC and all actors connected to it. As each actor has special conditions, simply make 3 different scenarios for each actor and depending on the actor decide which scenario to use. You can also use only 1 scenario and cover all the rules within it. This is even better choice, if the differences are relativelly small and easy to structure and define in a single point in scenario.

2. Use different UCs. You can alternativelly use a main UC and then derive 3 special use cases. Each actor gets "his own" use case. Main UC defined the main scenario, the geenric part of it (maybe just the squeleton) and 3 sub-usecases define their own special reqs.

There is also a third option, kind of mix, with the application of include-relationship (note, it's NOT extend). I find is kind of misleading though and too complicated (4 use cases, relationships).

For the same reason, I would suggest the 1st option. It discovers the main point of the use case (view list) and the fact that all 3 actor can use it. On the other side it surpresses the detailed rules to the inner-description of the element. Nice use of abstraction, the main modelling principle.

Here both diagrams: