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On the Rational course I attended we were advised that a common convention is to use a directional association from the triggering actor to the use case. We were also advised to assume that no explicit direction on an association indicates 2-way communication. So if, as is common, a use case communicates with another system (represented by a secondary actor), the association will generally have no direction arrow on it as such communication is usually 2-way. -----Original Message----- From: Brian G. Lyons [mailto:[EMAIL PROTECTED]] Sent: 10 October 2001 20:31 To: Eric D. Tarkington; Shukla, Susmita (CICG DTAG) Cc: ROSE_FORUM; Kurt Bittner; Geri Winters Subject: RE: (ROSE) Use case to actor Yes or No hiho, Heck, I was all ready to agree with Sushmita because I have been using a convention of having the actor that initiates the use case have a directed association to the use case in my use-case diagrams. But I am having trouble finding reference to doing this in any 100% official UML source. The directed association is a commonly observed pattern in use-case literature. Applying Use Cases: A Practical Guide by Geri Schneider and Jason Winters uses directed arrows in each direction between actors and use cases (see p127 & 177 of the first edition). Furthermore the Rational University training material for Requirements Management with Use Cases, for Principles of Object Technology, for Object-Oriented Analysis and Design with UML, and for Rational Unified Process Fundamentals (phew) all show the communicates associations pointing from actors to use cases. These courses mostly only show a directed arrow from an actor to a use case, but here and there you'll find arrows from use case to actor. You'll also find directed arrows going each direction in various articles such as this one from Software Development Magazine http://www.sdmagazine.com/documents/s=748/sdm0001d/ and this from the Rational Edge http://www.therationaledge.com/content/dec_00/t_ucnotfunctions.html Rational's web-based RUP product specifies in its section entitled "Guidelines: Communicates-Association": "Each role of a communicate-association has a navigability property, indicating who initiates communication in the interaction. Navigability is shown by an open arrowhead. If the arrowhead points to a use case, the actor at the other end of the association initiates the interaction with the system. If the arrowhead points to an actor, the system initiates the interaction with the actor. Two-way navigability is shown by a line with no arrow-heads." (v2001A.04.00.13) But then when I look at the UML Reference Manual I see all bi-directional associations and no mention of using an association that would point one way or the other. And I can't find an example or reference to a directed association in the UML Spec either. Oh well, I'll still keep using the convention of an arrow from the actor initiating the use case (disregarding data flow). And I even use arrows from use cases to secondary actors -- human or otherwise -- to show that the use case initiates communcation with the actor (again disregarding actual data flow). The use case diagram is there to communicate requirements and I like to know who is calling whom. -------- b -- Brian G. Lyons Number Six Software - Voted Rational's Best Complementary Service Provider 1655 North Fort Myer Drive, Suite 1100 Arlington, VA 22209-3196 http://www.numbersix.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Eric D. Tarkington Sent: Wednesday, October 10, 2001 12:28 PM To: Shukla, Susmita (CICG DTAG) Cc: ROSE_FORUM Subject: Re: (ROSE) Use case to actor Yes or No Susmita Shukla wrote: > Question: Can a use case "point to" an actor in a use case diagram? > > Answer: Yes. This would be a secondary actor. The actor provides > information needed to execute the use case. > > Hope this is simple enough. > > Susmita Shukla It's simple, but wrong, I think. The most important thing is that the use case diagram cannot indicate the direction of data or control flow between actors and use cases. If you want to discuss pointing, you probably need to use an interaction diagram or an activity diagram. That's why I discussed the use of actors in the sequence diagram. In that context, the question is: "Can an object point to an actor in a sequence diagram?" There, you can say "yes", because the diagram is capable of doing it. Once you are talking about the right diagram, you can introduce other nuances without confusion. -Eric ************************************************************************ * Rose Forum is a public venue for ideas and discussions. * For technical support, visit http://www.rational.com/support * * Admin.Subscription Requests: [EMAIL PROTECTED] * Archive of messages: http://www.rational.com/support/usergroups/rose/rose_forum.jsp * Other Requests: [EMAIL PROTECTED] * * To unsubscribe from the list, please send email * * To: [EMAIL PROTECTED] * Subject:<BLANK> * Body: unsubscribe rose_forum * ************************************************************************* --------------------------------------------------------------------------------------------------------------------- This email is intended for the named recipient(s) only. 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