Feature Question - Display Inherited Use Case Link

[Jones11]

Hi all, am entirely new to EA and like it a lot having used a fair few UML/OOAD tools over the last 15 years or so.

I have a question relating to use case modelling in EA.

Is it possible for EA to show in a use case diagram the use case links that are inherited by an actor. i.e. a generalised actor (base actor type) has a use case link (Use) specified. There are then also two sub-types of that actor and I would like to show on a diagram all links to use cases that the sub-type actors inherit from the base-type actor.

Many thanks,
Dave.

[sargasso]

Yes, it can.  Sort of.  If an actor is a specialisation of another then it is inherent in the diagram that any use case that is invocable by the generalisation is also invocable by the specialisation.

<use> (or "<uses>") does not immediately and clearly convey that inheritance, but when you get the clue ..  it does.

Consider :generaluser<<actor>> and the first level specialisation :supervisor<<actor>>.  There is no reason to suspect that any usecase invocation avaliable to an instance of :generaluser, say "makesale" is not also available to an instance of :supervisor.

UML unfortunately does "show" this explicitly.

hth
bruce  

[Jones11]

Hi Bruce,

Thanks for the prompt reply. Am aware of the implicit nature of use case inheritance, but this does not fit with how I would like to illustrate the use case model.

I would like to show the use case links for a given specialised actor. These links are both explicit links and inherited links.

For reasons of clarity and brevity, I don't wish to show the generalised actor on the same single diagram. It's a distraction. (The actor relationships serves a purpose to me as a use case modeller, but can be a distraction to the intended audience, the requirements stakeholders). The generalised actor is in my case a wholly conceptual actor and serves largely as a mechanism with the model; whereas the specialised actors are concrete actors in a real world sense.

It's true that given an actor diagram (of which one does exist) the relationships are apparent, but it should not be the case that I should be forced to use the generalised actor types throughout in order for the inherited links to appear on the diagram.

I would like simply to show all use cases that are linked to the actor (whether explicitly linked or inherited). I had hoped that there is a means to "Show Inherited links" if indeed not do this by default.

(We expect this style of behaviour re methods on specialised types on a sequence diagram - we are not forced to include the inheritance hierarchy.)

Cheers,
Dave.

[Paolo F Cantoni]

I would like to show the use case links for a given specialized actor. These links are both explicit links and inherited links.

Hi Dave,

We do this by using the derived property.  The inherited links are shown as derived by inheritance (stereotyped «inherited»).

Via bruce's point, it would be good if EA showed the parents for actors as It does for classes.  you might find that Rectangular notation for the actors may actually show them.

HTH,
Paolo

[Jones11]

Hi Paolo,

Not sure that I follow.

Are you saying that it's possible to include on a use case diagram the links (between actor and use case) that are purely inherited ?

If so how ?

Thanks and regards,
Dave.

[Paolo F Cantoni]

Hi Paolo,

Not sure that I follow.

Are you saying that it's possible to include on a use case diagram the links (between actor and use case) that are purely inherited ?

If so how ?

Thanks and regards,
Dave.

Unfortunately, by manual labour... (or an add-in, or by direct DB injection).  Unfortunately it's not namtive...

If generalized actor is a distraction, "you pays your money, you takes your choice".

Sorry couldn't be more help...
Paolo

[Jones11]

Hi Paolo,

No worries, have decided upon including the generalised actor types and providing a little education to the use case recipients if needed.

Thanks all,
Dave.