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On the way to the bank ....

From: Steve Ross-Talbot <steve@pi4tech.com>
Date: Tue, 11 Jul 2006 20:02:13 +0100
Message-Id: <81b7cdd56d464527a0e6692c7218a3ed@pi4tech.com>
Cc: Matthew Rawlings <matthew@stickledown.com>
To: 'WS-Choreography List' <public-ws-chor@w3.org>

I was speaking with Matthew Rawlings who chairs the ISO WG4 group about 
WS-CDL. He is the same person who asked why can't we have Participant 
with no roles.

The fundamental reason why Matthew asked the question (which he will 
submit further clarity for) concerns RoleTypes and ParticipantType.
We all know that ParticipantTypes are important because they support 
the type system. But they do so indirectly because of the roles that 
aggregate. RoleType names are used in ParticipantTypes and in locating 
variables and in cdl:functions. But supposing I want to express a
behavior (which we might call a role) that can be implemented in 
several ParticipantTypes. This is the same as the Buyer/Seller problem 
we have wrestled with before where several participants can provide the 
same behavior. Today we cannot share roles. The problem is almost
certainly because our ParticipantType is more of an instance than a 
type and the RoleType is very much a type. They are wrongly mixed.

Any ideas on how we can resolve the problem and so make it easier for 
choreographies to be expressed? I accept that WS-CDL as is is infact
complete to express all that we might wish to do but it is less than 
optimal at doing so.


Steve T
Received on Tuesday, 11 July 2006 19:02:43 UTC

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