[Modeling] Modeling an Agent Class- register your opinion

Fri, 20 Jun 2003 12:52:29 +0100

----- Original Message ----- 
From: "Joaquin Peña" <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 9:17 AM
Subject: RE: [Modeling] Modeling an Agent Class- register your opinion

> Right, as the department agent is like a coordinator of its
> employees this relation can be view as a "congregation" at
> organizational level (or view). But, I guess that a department is
> more a resource than an agent, unless it coordinates the employees
> community in someway.
>
> If it coordinates agents, at the interaction view (we use role
> models for modelling interactions between agents) it is just a
> relation/relations between agents. That it is to say, a set of
> role models that models the common interaction between employees
> and its department in order to achieve system goals.
>

Just to add to your comments, as an agent, a department not only coordinates
the employees, but also interacts with other agents in the system, such as
other departments, and the university, etc. It also have an active
behaviour. Therefore, it is not just a relation.

Hong

>
> > -----Mensaje original-----
> > De: Dr. Hong Zhu [mailto:hzhu@brookes.ac.uk]
> > Enviado el: viernes, 20 de junio de 2003 10:05
> > Para: Joaquin Peña; 'Wagner, G.R.'; 'James Odell '; 'ModelingTC '
> > Asunto: Re: [Modeling] Modeling an Agent Class- register your opinion
> >
> >
> >
> >
> > ----- Original Message ----- 
> > From: "Joaquin Peña" <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 Peña
> > >
> > >
> > > > -----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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