[Modeling] Comments on interaction diagram modeling doc

[Wagner, G.R.]

> In terms of the work we are doing, this document raises the question
> as to whether protocol specifications should be between agents (or
> agent types) or between roles. 

How do you distinguish these two concepts? Ontologically,
there is a distinction between what Guarino has called
a "rigid" type and a "non-rigid" type: an instance of
a rigid type will always be an instance of that type
(during its lifetime), while an instance of a non-rigid 
type may cease to be an instance of that type. A role
corresponds to a non-rigid type. UML allows for dynamic 
classification, which means that a role type, say
Customer, can be modeled as a subtype/subclass of a 
rigid type, say Person. Of course, it would be good
to designate role types in UML diagrams, e.g. by means
of a stereotype <<role>>. We may use this flexibility
of UML classes to represent both rigid and role types
also in AUML interaction diagrams.

-Gerd

---------------------------------------
Gerd Wagner  
http://tmitwww.tm.tue.nl/staff/gwagner/
Dep. Information & Technology 
Eindhoven University of Technology  
Email: G.Wagner@tm.tue.nl 
Phone: (+31 40) 247 26 17  
Fax: (+31 40) 247 26 12