And this can all be found in Jacobson's REUSE book (1997), the same one
Richard Howlett mentioned but then a few pages back.
Page 205 gives a good picture of the technique of finding the SUBSYSTEM's
use cases from the realization (sequence diagrams) of the SYSTEM's use
cases.
my two cents,
Dik van Leeuwen
----- Original Message -----
From: Crain, Anthony R. <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Thursday 8 February 2001 22:05
Subject: RE: (ROSE) Question About Actors
I did some training to Daimler Chrysler within the last eight weeks. Fun
bunch. I did not actually miss the point you refer to. Use cases and
actors are defined for a given scope.
If your scope is the super system, the actors are the people or things I
interact with at the super system level. The subsystems would not even
appear until I got into the DESIGN of the super system. That design would
be done via sequence diagrams (in my house).
Once I was ready to develop the subsystems, the scope would change. I
would
do the use cases of my subsystem. Now the actors could either be the same
as those for my super system if my subsystem was responsible for working
with that actor, and other actors would be the other subsystems.
I do not model any relationship between the two different scopes. well
actually I do, but not in a use case diagram.
So for a given scope, actors external, use cases internal. Change your
scope, things change, but actors are still outside, and use cases are still
inside.
--anthony
> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, February 08, 2001 6:52 AM
> To: Crain, Anthony R.; [EMAIL PROTECTED]
> Subject: RE: (ROSE) Question About Actors
>
>
>
>
> Anthony,
>
> You missed one small point that is crucial in a large distributed
> development system. The concept of scope, a large system that
> is made up of
> loosely connected autonomous subsystems which send and
> receive data between
> them only as required to perform a function of their own system.
>
> The system supplying the data is an actor to the system requesting the
> data. It is external, developed separately, with different purpose.
>
> To the overall system, which ties all the subsystems
> together, it is part
> of the process being developed. So, to the team developing
> application A,
> the control system is merely an actor. To the team developing
> application
> B, the control system is merely an actor. To the team
> integrating the whole
> damn lot together A,B and the control system are just
> components. Note, B
> and A are not actors of each other as they do not interface directly.
>
> The situation becomes even more complicated when trying to include
> "knowledge" in the control system as this then does not only
> respond to
> prompt from the subsystems via their actors but can also
> instigate actions
> on the subsystems.
>
> In conclusion, do what figure out what fits well with your
> projects needs,
> agree it with your team and get on with it. If it doesn't
> fit, don't use
> it.
>
> Mark
>
>
>
>
>
> "Crain, Anthony R." <[EMAIL PROTECTED]>@rational.com on 02/07/2001
> 06:39:02 PM
>
> Please respond to "Crain, Anthony R." <[EMAIL PROTECTED]>
>
> Sent by: [EMAIL PROTECTED]
>
>
> To: Colin Gourlay <[EMAIL PROTECTED]>, "'Pankaj
> Chatterjee'"<[EMAIL PROTECTED]>, "Rational
> Rose Forum
> (E-mail)"<[EMAIL PROTECTED]>
> cc:
>
> Subject: RE: (ROSE) Question About Actors
>
>
>
> Actors are outside the system. The whole purpose of
> identifying actors is
> to show the boundary of what is in the system and what is
> outside of the
> system.
>
> The "of value" part of your explanation is good though. And
> it does not
> conflict with the idea that actors are external.
>
> Stakeholders in RUP are anyone who would be materially
> affected by the
> system if it were built correctly. But not all stakeholders
> are actors.
> The difference? Some stakeholders interact with the system,
> others do
> not. The ones that do are actors, the ones that do not are not. The
> actor name may match up with the stakeholder name, but often do not.
>
> Jane runs a university, and if we build a registration system, she is
> materially affected, thus is a stakeholder. However, there may be no
> requirements that the system directly help her run the university, so
> there would be no use cases for her. Thus she would not be an actor
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