[Modeling] Modeling an Agent Class- register your opinion
Fri, 20 Jun 2003 09:43:32 +0200
Are you think in employees and departments as different agents?
I'm agree with you: part-whole relationship in UML is not
adequate. I see this relation as an "use relation" of a resource.
That if one of the parts is destroyed, this use is finished.
> -----Mensaje original-----
> De: firstname.lastname@example.org [mailto:email@example.com]
> En nombre de Dr. Hong Zhu
> Enviado el: viernes, 20 de junio de 2003 9:31
> Para: Wagner, G.R.; James Odell ; ModelingTC
> Asunto: Re: [Modeling] Modeling an Agent Class- register your opinion
> The point is: the destroying of the whole (i.e. a department)
> cause the parts (i.e. the members) to lost its class
> membership to an 'agent class' (i.e. member of the
> department). What I am saying is that, the definition of
> part-whole relationship in UML in terms of shareability is
> not adequate. Even shareability plus lifetime cannot define
> the kind of part-whole relationship we need to deal with
> agent's part-whole relationships.
> I agree with you that, in agent-orientation, shareability
> does not imply lifetime dependency. However, I think, in
> object orientation, shareability does imply lifetime
> dependence. Because, if a part object is not shareable, then
> when the whole object is destroyed, the part objects become
> garbage. It life is then also finished. Am I right?
> ----- Original Message -----
> From: "Wagner, G.R." <G.R.Wagner@tm.tue.nl>
> To: "Dr. Hong Zhu " <firstname.lastname@example.org>; "Wagner, G.R."
> <G.R.Wagner@tm.tue.nl>; "James Odell "
> <email@example.com>; "ModelingTC " <firstname.lastname@example.org>
> Sent: Thursday, June 19, 2003 5:57 PM
> Subject: RE: [Modeling] Modeling an Agent Class- register your opinion
> > > The relationship between the department and it members is
> > > from composite in UML, because the agent is still alive after the
> > > owner is destroyed. It is also different from aggregation because
> > > the destroy of the owner (the department) affects the
> behaviour of
> > > the member agents
> > > lost the membership of department members and the associated
> > > capability
> > > accessible resources). If an object is a part of another
> object as
> > > an aggregate, the destroy of the owner will not affect the part
> > > object's membership to any class, so does not affect its
> > Hong,
> > again, the difference between aggregaion and composition is
> simply the
> > property of shareable parts. The property of lifetime
> dependency you
> > refer to is orthogonal to this.
> > Obviously, in your example, there is an aggregation relationship
> > between the members of a department and the department (because a
> > member can be also a member of another department, i.e.
> members can be
> > shared). An aggregation relationship does not imply anything wrt
> > lifetime dependency and it does neither imply that it would
> not affect
> > its parts. These are additional, othogonal issues.
> > So, your conclusion that we need a "third" part-whole
> relationship is
> > unfounded.
> > -Gerd
> > > ----- Original Message -----
> > > From: "Wagner, G.R." <G.R.Wagner@tm.tue.nl>
> > > To: "Dr. Hong Zhu " <email@example.com>; "James Odell "
> > > <firstname.lastname@example.org>; "ModelingTC " <email@example.com>
> > > Sent: Tuesday, June 17, 2003 9:03 PM
> > > Subject: RE: [Modeling] Modeling an Agent Class- register
> your opinion
> > >
> > >
> > > > > The part-whole relationship between agents are also
> > > > > The aggregation relationships between the whole and part is
> > > different in
> > > > > agent classes from that in object class. In object
> > > there
> > > are two
> > > > > types of whole-part relations:
> > > > > (1) composition, in which the lifespan of the whole
> and the part
> > is
> > > the
> > > > > same, and (2) aggregation, in which the lifespan of the whole
> > > > > and
> > > part
> > > > > is independent. Having two whole-part relations is inadequate
> > > > > for agent-orientation due to agent's autonomous behaviour. For
> > example,
> > > we
> > > > > have a agent which represents a department in a
> university, and
> > > > > a
> > > number
> > > of
> > > > > agents as members of the department. When the department is
> > > destroyed,
> > > > > the members as individuals still exist, but their class
> > > > > membership
> > > as
> > > the
> > > > > member of the department are lost.
> > > >
> > > > This is a misunderstanding of the UML aggregation concept.
> > Composition
> > > > is defined as a "non-shareable" aggregation, and not
> via lifetime
> > > dependency.
> > > > There are some misleading remarks about lifetime
> dependency in UML
> > > 1.4.
> > > > Lifetime dependency is implied in aggregations with inseparable
> > parts.
> > > > It's not related to shareability. Please see my
> ODBASE'2002 paperr
> > on
> > > > ontological foundations of UML (on my homepage) for further
> > > explanattions.
> > > >
> > > > Of course, all general ontological isssues of the part-whole
> > > relationship
> > > > apply to all things, no matter if they are agents or objects.
> > > >
> > > > -Gerd
> > > >
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