if A is extension use case (not base use case), can A be directly referenced by the actor?
A:
You can make the case that there are two kinds of use cases:
Abstract -- not directly experience by an actor, but extensions ("subclasses") are.
Concrete -- experienced by an actor.
S.Lott
2008-11-05 19:52:47
in use-case terminology, I don't think extensions are like subclasses, they're more like 'alternate paths'
Steven A. Lowe
2008-11-06 02:50:51
@Steven A. Lowe: the "alternate" is roughly analogous to a subclass which overrides selected steps. Use Cases are defined as being object-oriented by Jacobson. They're not literally classes, but there are intentional parallels.
S.Lott
2008-11-06 03:02:36
@[S.Lott]: use-cases have a Generalization relationship, different from Extends (see http://publib.boulder.ibm.com/infocenter/rsmhelp/v7r0m0/index.jsp?topic=/com.ibm.xtools.modeler.doc/topics/cextend.html) - but i think i agree with your analogy, extension points are like overridden methods...
Steven A. Lowe
2008-11-06 03:24:06
Extension points are really like conditionally inserted methods, rather than overridden methods.
Doug Knesek
2009-11-16 01:37:30
A:
yes; the fact that A extends some other use-case does not 'hide' it from actors
Steven A. Lowe
2008-11-06 02:51:30
+1
A:
YES The user can as said above, but does not indirectly reference/use it, it must be explicitly modeled.
Drive Truck extends Drive Steering Based Vehicle. It make sense that the Actor could reference either.
Ted Johnson
2008-11-09 20:23:01