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Re: Hypermedia workflow

From: Miles Sabin <miles@milessabin.com>
Date: Sun, 22 Dec 2002 12:05:28 +0000
To: www-ws-arch@w3.org
Message-Id: <200212221205.28918.miles@milessabin.com>

Assaf Arkin wrote,
> In fact, my experience, just like yours, proves that any multi-party
> choreography can be broken down into a set of two-party interactions,
> and any set of two-party interactions that is performed in the proper
> order would result in a multi-party interaction.

I think it's uncontroversial that from a technical point of view this 
transformation can always be done in principle. I'm less sure that the 
resulting pairwise protocol would always have desirable efficiency and 
robustness characteristics ... eg., wrt efficiency, compare true 
broadcast with a pairwise emulation; or wrt robustness, the pairwise 
protocol might depend on an auxiliary coordinator which might be a 
single point of failure.

From a non-technical point of view, I'm worried that legal 
considerations might get in the way of reducing multi-party to pairwise 
interactions: in a jurisdiction which recognizes multi-party agreements 
as legal primitives it could be the case that a transformation to 
pairwise agreements changes the legal landscape in unexpected or 
unfortunate ways. Maybe there just aren't any jurisdictions which 
recognize primitive multi-party agreements, in which case this is a 
non-problem. But nobody has managed to provide me with convincing 
evidence that this is so (yet), and I can't think of any a priori 
reason why it should be.

And even if the legalities are pairwise-friendly, it might still be the 
case that informal business agreements are often multi-party, with an 
only hazy connection with background legally binding pairwise 
agreements. Those informal agreements might Just Work sufficiently well 
in enough cases that any disconnect with the legal background aren't 
troublesome. On the contrary, aligning a practical multi-party 
agreement with a strictly legally binding set of pairwise agreements 
might be too time-consuming and expensive to be worthwhile. The problem 
here is that automating this stuff would be dependent on that alignment 
being done upfront, and that might be a significant obstacle.

I for one don't know how to begin to answer these last questions ... 
this looks more like territory for lawyers and sociologists than for 
protocol designers.

Cheers,


Miles
Received on Sunday, 22 December 2002 07:06:01 GMT

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