Hi Vladimir,

you are right, a use case does something. In lack of time I shortend my example
to much. What I tried to express is:

1) The user (human actor) initiates a use case, but this is not expressed by an
arrow but by a line meaning "is involved in". The kind of action of the user is
expressed in an underlying sequence diagramm, in prosa or whatever. If necessary
for presentation you can add a note to the UCD.

2) The use case does something relevant for the user and his business. It
produces the result as an output on screen (or printer). Now the same or another
actor (human/system) has to add information or decision.

3) The system waits for additional input. This is documentated inside the use
case (SD, prosa,...) or the use case should (again: ???) be divided. I have no
guideline handy when to split or not. I feel (!) when the use case produces a
1000 pages document at the first of the month and the manager enters his
decisions upon that at the end of month I would split the use case. If a use
case just adds one and one and presents zwo waiting for more input I would not
do so. However methodically there is no difference between the examples. Time or
page number are no usable arguments as well as the number of UC you will get at
the end.

In short: a use case does something and has several actors. But, to the original
question we once had, in the use case diagramm it doesn't trigger a human and
waiting for input is formally not expressed there (except in a note for
presentation). The associations between actors and UCs are NON-directional (or
BI-directional, which is probably the same in this context).

Stefan






Vladimir Riecicky <[EMAIL PROTECTED]> am 11.10.2001 15:50:53

Bitte antworten an [EMAIL PROTECTED]

An:   Stefan Birner
Kopie:    Rational Rose Forum <[EMAIL PROTECTED]>

Thema:    Re: Antwort: Re: (ROSE) Use case to actor Yes or No



Hi Stefan,


> 2) As I have found in an old UML-rules-document, if a use case is interupted
in
> time, it should (?) be devided into two use cases. For example, if the user
> initiates a use case that produces an input screen, the use case ends with the
> display. If the user enters data, another use case starts. A user/human is not
> "triggered" or whatever.

Well, I somehow miss in your ideas the original purpose and intention of use
cases, which
is delivery of REAL goal to actor.
I can hardly believe that "producing input screen" is a candidate for reasonable
use case
at all! As far as I can understand, you are trying to introduce a constraint
that use
case can be associated only to its primary actor. I find this completely wrong
with
respect to real use case concepts.
Moreover, just try to imagine with how many use cases would you and up (if you
ended up
at all) modeling a real world application.....I bet for a hudge number.

Vladimir.

>
>
> Stefan
> www.sbirner.de
>
> "Eric D. Tarkington" <[EMAIL PROTECTED]> am 10.10.2001 17:28:19
>
> Bitte antworten an "Eric D. Tarkington" <[EMAIL PROTECTED]>
>
> An:   "Shukla, Susmita (CICG DTAG)" <[EMAIL PROTECTED]>
> Kopie:    ROSE_FORUM <[EMAIL PROTECTED]> (Blindkopie: Stefan
>       Birner/TLC/DE)
>
> Thema:    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
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      Stefan Birner
      DB AG - LH Systems AS GmbH
      PFI CIO / Programm it-p Datenmanagement
      Raum A EG 33, Stephensonstrasse 1, 60326 Frankfurt
      Tel.: +49 (69) / 265 -6599
      FAX: +49 (69) / 265 -7546
      Mobil: +49 (178) / 765 2849
      eMail: [EMAIL PROTECTED]



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