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RE: xml:id and opacity of refp's

From: Savas Parastatidis <Savas.Parastatidis@newcastle.ac.uk>
Date: Thu, 6 Jan 2005 11:08:43 -0000
Message-ID: <37E80E80B681A24B8F768D607373CA800197B69E@largo.campus.ncl.ac.uk>
To: <public-ws-addressing@w3.org>

> > >  Opaqueness as an operating principle is important to protect
> > > service requester interoperability.
> Why?  I mean, what's the technical reason for this?

To my mind, the fundamental issue behind reference properties/parameters
and the reason for the value or not of opaqueness is that through
RefProps/Params we are creating a placeholder inside an address for
service-specific knowledge. This encourages service-builders to couple
application-domain specific knowledge with service references (the
EPRs). It also moves knowledge from the application level (e.g. resource
id, order id, bank account number, etc.) down to the infrastructure
(e.g. the way in which we address services). I believe that the two
should remain orthogonal but unfortunately RefProperties/Params
encourage the opposite, hence encouraging many to treat them as
addresses of backend resources.

That's why I personally prefer WS-Context. It has clear semantics since
it clearly identifies a placeholder for defining interaction scope (the
semantics are known to all parties involved) but without requiring the
semantics of its contents to be known to all. There is no coupling with
addresses. The scope of the interaction does not become part of the
service reference.

Please note that the above observations hold true for wsa:action too
:-))) The purpose of the message payload can be inferred only by the
ultimate recipient within the scope of a particular interaction (the
interaction being of arbitrary length in numbers of messages).

Few thoughts to start the 2005 discussions :-)

Best regards,
Received on Thursday, 6 January 2005 11:09:35 UTC

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