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Re: WS-CDL and (polyadic) Pi-Calculus

From: Paul Bouche \(HPI\) <paul.bouche@hpi.uni-potsdam.de>
Date: Tue, 17 Jan 2006 12:32:00 +0100
Message-ID: <43CCD5B0.3040208@hpi.uni-potsdam.de>
To: "Steve Ross-Talbot" <steve@pi4tech.com>
Cc: <public-ws-chor@w3.org>

Hi,

thanks Ingo and Steve for your answers.

The IMHO goes for all I am about to say.

Ingo, channels and sending of channels, I clearly see as inspired from 
Pi, but the work unit concept, all the concepts finalizer, exception, 
roleType, participantType, bahaviour and state mangement concepts I 
don't see how the were inspired from Pi. Those are added and more 
high-level than Pi. The grouping concepts for activities are clearly 
those of Pi: Seqeunce, Parallel, Choice. Yet there is a 
while-loop-grouping construct which is also not found in Pi. Surely all 
these concepts can be expressed with Pi-Calculus with more or less 
effort. The exchange interaction concepts also is clearly inspired by 
Pi. Pi does not differentiate between variables, channelTypes, 
channelType instances, names of channels, tokens etc. This is another 
high-level addition. Also from my knowledge Pi-Calculus is not typed at 
all, it does not even have a data flow centric concept but it is all 
process centric or oriented.  This orientation I cannot clearly see in 
WS-CDL. Yet this may also not be possible because of the goals for 
WS-CDL, and also because of that high-level constructs had to be added.

Steve are you refering to [1], [2] and [3] when you talk about "Global 
Calculus"? What does "Q22006" mean - 12/22/2006 - which would be 
December 12th 2006?

Thank you for you inputs!
Paul

[1] Carbone, Honda, Yoshida, "Programming interaction with Types" ,  
http://www.w3.org/2002/ws/chor/5/06/F2FJune14.pdf

[2] Kavantzas, "Aggregating Web Service: Choreography and WS-CDL", 
http://lists.w3.org/Archives/Public/www-archive/2004Aug/att-0017/WS-CDL-April2004.ppt

[3] Honda, Yoshida, et. al. "A Theoretical Basis of 
Communication-Centred Concurrent Programming", 
http://lists.w3.org/Archives/Public/public-ws-chor/2005Nov/att-0015/part1_Nov25.pdf

Steve Ross-Talbot wrote:

> Deal Paul,
>
> Yes the channels where inspired by pi-calculus. They are a channel or 
> port pairing. The work of our invited experts looks at providing a new 
> calculus called CG (Global Calculus). When we project participants we 
> do so to an EPC (End Point Calculus) which is pi-calculus with session 
> types. The session information comes from the identity tokens 
> described as part of a channel type. This EPC is what we use to 
> enforce liveness and other relevant properties (bi-simulation etc).
>
> The plan is to publish the finished treatment of GC and EPC sometime 
> in Q22006 as a working note.
>
> Hope this helps
>
> Steve T
Received on Tuesday, 17 January 2006 11:32:10 GMT

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