[Modeling] Modeling an Agent Class- register your opinion

Wagner, G.R. G.R.Wagner@tm.tue.nl
Tue, 17 Jun 2003 22:03:39 +0200

> 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.