I think that is the whole point of OO models
Objects are like and could be an actor ... it can tell something else to do
something
but the only real actors in a model are everyone and everything OUTSIDE the
system that are using the system. If something is triggered by Time, then
the Time is an Actor
if something is triggered by the Wind .. then the Wind is an Actor.
Not the object that checks the time or windspeed
----- Original Message -----
From: "Colin Gourlay" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, February 27, 2001 10:11 AM
Subject: Re: (ROSE) "System" as Actor
>
> This is an interesting question you pose Eric.
>
> I am quite new to UML and have been doing precisely what you're students
> have been doing. In a separate post, in recent weeks, where I stated
> something to the effect that an actor either gives value to or gets value
> from a use case and went on to say that an actor can be external or
internal
> to the system under discussion I found that the general consensus of
opinion
> was that Actors are external and *not* part of the system under discussion
>
> That is, both your students and myself appear to have been doing this
> incorrectly.
>
> I accepted what other posters said *but* I would like to pose pretty much
> the same question as yourself but relate it to my own circumstances...
>
> I am writing a middleware application that is to integrate disparate
> systems. The system under discussion has to poll other systems and
devices
> (these were my external actors) and react accordingly upon receiving
> messages, data or whatever. In this SuD I had an actor (a stereotyped
> class) that was responsible for polling and generally *controlling* the
> coordination/sequence of events of the use cases in the SuD. This actor
as
> I saw it was very much central (not in a behaviourla sense but in a
> controlling context) to the system being designed.
>
> As Eric says if it "...looks like an actor, walks like an actor, and
quacks
> like an actor, what is it?"
>
> Or is this newbie (me) missing something completely??
>
> Regards
>
> Colin
>
>
>
>
> ----- Original Message -----
> From: Eric D. Tarkington <[EMAIL PROTECTED]>
> To: ROSE_FORUM <[EMAIL PROTECTED]>
> Sent: Monday, February 26, 2001 9:59 PM
> Subject: (ROSE) "System" as Actor
>
>
> >
> > When drawing their first use case diagrams, my students (including some
> > of my best) sometimes identify the system under development as an actor.
> >
> > I've been telling them not to do this, since my favorite sources don't
> > do it, but lately it has been bothering me.
> >
> > When the system is doing something like scheduling activities for
> > regular or delayed execution, I have seen authorities use a "system
> > clock" actor. Also, in some environments it is quite right to say that
> > the system provides services such as printing. If the system looks like
> > an actor, walks like an actor, and quacks like an actor, what is it?
> >
> > -Eric
> > ************************************************************************
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