I need to show that several systems are interacting with each other but without going into too much detail. I've decided to use a use case diagram so my question is: how wrong would it be to have an association relation between actors (interfaces) as well?
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See also https://www.uml-diagrams.org/activity-diagrams-examples.html – xmojmr Jul 31 '18 at 10:40
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Actors are not interfaces. That's simply a wrong assumption. – qwerty_so Aug 01 '18 at 00:35
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I cannot imagine the purpose of drawing direct association between actors. That would mean that an association exists between actors but the association is outside the modeled system. So it is just a note that has no impact on functionality of the modeled system. I would say that the actors are usually linked by using one common use case - that would be the association inside the modeled system with some impact on the functionality.
I personally prefer to associate use cases to processes rather than actors.
Vojtěch Dohnal
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So in my case that I need to show my main system interfaces how would you suggest to model it? – Joanna M. Jul 31 '18 at 10:17
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I do not know much about your task from the question, but I would say that *use case = interface* Use case is a functionality that system presents to using actors or processes, like a red button to press. – Vojtěch Dohnal Jul 31 '18 at 10:21
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Like Vojtěch mentioned, is not preferable to do so. You are modeling the system, and actors are indeed NOT a part of it, which could lead to some conclusions:
- You are adding a not that-valuable info
- Your domain/boundaries are not correct, and need to get bigger and include at least one of those actors.
BUT, there are exceptions to these rules
- A model is a simplification of the reality and UML is the language to be able to communicate in the industry. I personally never allow UML get in the way to express what I want with a diagram/model.
If I find is imperative to make contextual information of the relations betweens actors I would go ahead and do it, normally I use notes, the element's description and yes, eventually associations.
- Generalisation, however, are usually involved in both software and business use cases. That would not only explain the relation between the actors, but also will allow you to suppress the all the lines of the child, since the father normally will do them all.
Joako-stackoverflow
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