Re-statement of Issue 662

Issue 662 against the WS-Choreography specification is in the Layers and
Levels category and has the summary: specify at least two levels or types of
Choreography description.
 
The current issue description reads: 
"The first draft of the proposed Choreography description language contained
the definition of three levels of description: abstract, portable and
concrete.
Personally I had some sympathy with this notion, though it was debated as to
how many levels were required and what the precise definition of each should
be.
As the notion of levels has been removed completely from the current editors
draft, I would like to raise an issue on this.
Levels or types of Choreography description: I suggest that we should
specify at least two levels or types of Choreography description.
One level could be called abstract or business process oriented or some
such. It would support focus on the definition of the business exchanges. It
would specify the allowed sequencing of messages and the nature of
eachmessage. It would not have to provide a precise specification (/schema)
for each message nor how each message was to be transported. This it would
allow agreement of the basic business 'protocol' but would be insufficientto
enable interoperability on its own.
Another level or type of Choreography description would provide a precise
specification and schema for each message and how each message was to be
transported. It would thus be a basis for interoperation or at least provide
the interoperability specification of the upper layers of the protocol
stack."

I would like to re-state this issue 662 as follows:
 
"The same choreography can be described at different levels levels of
detail.  One extreme contains only the minimum of detail to describe the
choreography - the basic sequencing of types of messages and could be
referred to as abstract or business oriented or some such.  This level would
be easiest to write by hand and should aid gaining human agreement to the
choreography amongst potential participants and other interested parties.
Other descriptions of the same choreography could be produced that contain
progressively more detail until all the features of the choreography
language and other languages it makes use of, particularly the Web Service
Description Language, are being used to their fullest extent.  This level of
detail should aid interoperability of participants implementing this
choreography.
 
Thus the issue is to ensure that the Choreography Description Language
Schema and specification text support sufficient and appropriate optimality
to support the crafting of descriptions of the same choreography at
different levels of detail.
 
Best Regards     Tony
A M Fletcher
 
Cohesions  (TM)
 
Business transaction management software for application coordination
www.choreology.com <http://www.choreology.com/> 
 
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