[Modeling] Modeling an Agent Class- register your opinion
Dr. Hong Zhu
hzhu@brookes.ac.uk
Fri, 20 Jun 2003 12:45:59 +0100
Hi, Frits,
----- Original Message -----
From: "f.tolman" <f.tolman@chello.nl>
To: "Dr. Hong Zhu" <hzhu@brookes.ac.uk>; "Joaquin Peņa" <joaquinp@us.es>;
"'Wagner, G.R.'" <G.R.Wagner@tm.tue.nl>; "'James Odell '"
<email@jamesodell.com>; "'ModelingTC '" <modeling@fipa.org>
Sent: Friday, June 20, 2003 12:13 PM
Subject: Re: [Modeling] Modeling an Agent Class- register your opinion
> Dear Hong
>
> Why don't you describe complex agents like departments as CompoundAgents,
> and a CompoundAgent as an aggregate of Agent?
I am regarding department as a CompoundAgent that has a number of agents
(the members) as parts (maybe, there should also some other agents and
objects as its parts). The question that I am discussing about is what is
the relationship between the whole (the department) and the parts (the
members). Is it the compite relation, or is it the agregate relation? In my
point of view, as I have said in previous emails, none of these two is
correct for the relation between department and its members. Such relations
between agents, I believe, are common in agent-oriented modelling.
> Some way or the other the word
> Caste to me has the wrong flavour. Also I miss the notion of Agent in your
> meta model.
I have not completed my meta-model, yet. But, briefly, agents are instances
of castes. Similar to objects are instances of class. Of course, caste has
some features and structures that class in traditional OO do not have. And
agent has features and structures that traditional objects do not.
>
> When you simply use the word Agent as the class name of the class Agent
you
> can produce a meta model in UML. Using UML as the modelling language does
> not mean that the behaviour of agents necessarily has been limited to OO.
>
I don't think the semantic definition of UML can be interpreted that way.
> Regards
>
> Frits
>
>
Regards,
Hong
>
> ----- Original Message -----
> From: "Dr. Hong Zhu" <hzhu@brookes.ac.uk>
> To: "Joaquin Peņa" <joaquinp@us.es>; "'Wagner, G.R.'"
> <G.R.Wagner@tm.tue.nl>; "'James Odell '" <email@jamesodell.com>;
> "'ModelingTC '" <modeling@fipa.org>
> Sent: Friday, June 20, 2003 10:04 AM
> Subject: Re: [Modeling] Modeling an Agent Class- register your opinion
>
>
> >
> >
> > ----- Original Message -----
> > From: "Joaquin Peņa" <joaquinp@us.es>
> > To: "'Dr. Hong Zhu'" <hzhu@brookes.ac.uk>; "'Wagner, G.R.'"
> > <G.R.Wagner@tm.tue.nl>; "'James Odell '" <email@jamesodell.com>;
> > "'ModelingTC '" <modeling@fipa.org>
> > Sent: Friday, June 20, 2003 8:43 AM
> > Subject: RE: [Modeling] Modeling an Agent Class- register your opinion
> >
> >
> > > Are you think in employees and departments as different agents?
> > >
> >
> > Yes, an employee is a different agent from a department, although they
are
> > both 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.
> > >
> >
> > I would not call it 'use relation'. In CAMLE language, we now call it
> > 'congregation' to indicate that the whole is an agent that is formed by
a
> > set of agents gethered together.
> >
> > Hong
> >
> >
> > > Joaquin Peņa
> > >
> > >
> > > > -----Mensaje original-----
> > > > De: modeling-admin@fipa.org [mailto:modeling-admin@fipa.org]
> > > > 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
> > > >
> > > >
> > > > Gerd,
> > > >
> > > > 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?
> > > >
> > > > -Hong
> > > >
> > > > ----- Original Message -----
> > > > From: "Wagner, G.R." <G.R.Wagner@tm.tue.nl>
> > > > To: "Dr. Hong Zhu " <hzhu@brookes.ac.uk>; "Wagner, G.R."
> > > > <G.R.Wagner@tm.tue.nl>; "James Odell "
> > > > <email@jamesodell.com>; "ModelingTC " <modeling@fipa.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
> > > > different
> > > > > > 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
> > > > (they
> > > > > > lost the membership of department members and the associated
> > > > > > capability
> > > > and
> > > > > > 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
> > > > behaviour.
> > > > >
> > > > > 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 " <hzhu@brookes.ac.uk>; "James Odell "
> > > > > > <email@jamesodell.com>; "ModelingTC " <modeling@fipa.org>
> > > > > > 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
> > > > different:
> > > > > > > > The aggregation relationships between the whole and part is
> > > > > > different in
> > > > > > > > agent classes from that in object class. In object
> > > > orientation,
> > > > > > 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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