Re: Transactional Web Services (LONG)

[Jeff Greif <jgreif@alumni.princeton.edu>]

Excellent explanation!  Is it guaranteed that the souk model can work with
only pairwise interactions?  Is there an assumption or guarantee that the
parties always know how (out of their own self-interest) to fix any
consistency problems arising from the failure to complete somewhere along
the way, or that it is always possible (there's no way for one party to be
out of touch for too long)?  Do the models produce "equivalent business
outcomes" when the transaction is aborted, since the costs of compensating
transactions in the 2PC case may be much less than the cost of the cascade
of operations needed to fix up whatever parts of the more autonomous
transaction may have completed when someone decides to abort?

Jeff

----- Original Message -----
From: "W. E. Perry" <wperry@fiduciary.com>
To: "XML DEV" <xml-dev@lists.xml.org>
Sent: Friday, August 24, 2001 8:19 AM
Subject: Re: Transactional Web Services (LONG)


> By contrast, the 'principal' form of transaction which I propose in the
'souk'
> model is a single commitment between autonomous peers whose individual
> instantiation of the the data substance of the transaction and subsequent
> further processing is beyond the reach of the other party. Such a
transaction is
> concluded when one party agrees to the specifics as offered at that moment
by
> the other party, which then accepts that agreement. There is no question
of
> achieving a consistency of result. It is however generally necessary that
> further transactions be executed to satisfy the logistical demands crated
by the
> original execution. Payment must be arranged, as well as delivery. The
> expectation of the souk model is that each such step will entail a further
> unique principal transaction between autonomous parties. The party
accepting the
> terms of execution offered by the other will then need to effect a
transaction
> versus its bank to arrange payment. The other party will need to effect a
> transaction to procure shipment. The shipper will then need to effect a
> transaction versus the purchaser in order to arrange a delivery. The
purchaser's
> bank will need to effect a transaction versus the seller in order to
arrange the
> transfer of funds. Each of these transactions is effected between
principal
> parties:  the purchaser's bank, for example does not mediate or broker
between
> the purchaser and the seller. The execution of each of these transactions
> confirms the terms of the others. If the seller balks at the terms of
payment
> offered by the purchaser's bank, it has the option of returning to the
purchaser
> to cancel the original deal through an offsetting transaction. Otherwise,
the
> seller's acceptance of the bank's terms corroborates the individual
> understanding of the original transaction's terms by each of those
original
> parties.
>
> In the aggregate, the execution of a group of transactions, each of them
by
> autonomous principal parties, achieves an equivalent business outcome to
the
> propagation, by the agency of 2PC, of a single much more complex
transaction to
> all of the interested parties. The advantages of the principal, rather
than the
> agency, approach are a much greater simplicity and comprehensibility in
the
> terms of each individual execution, and the ability for parties to execute
what
> they understand, without having first to agree to the form and
representation of
> data which is only ancillary to the transaction as they understand it, and
at
> best tangential to their own role and expertise in the specific
transaction
> which they understand and care about.