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Re: Proposed issue; Visibility of Web services

From: Mark Baker <distobj@acm.org>
Date: Tue, 27 May 2003 15:58:04 -0400
To: Anne Thomas Manes <anne@manes.net>
Cc: www-ws@w3.org
Message-ID: <20030527155804.P31140@www.markbaker.ca>

On Tue, May 27, 2003 at 02:25:26PM -0400, Anne Thomas Manes wrote:
> A generic HTTP intermediary has little if any visibility into an HTTP POST
> request if the contents of the HTTP message contain binary data.

Yes, in practice, POST is a bit of a black hole in that respect (but
with any data, not just binary).

FWIW, a RESTful use of POST is quite visible; an intermediary knows that
there is no expectation of anything happening other than the POST action
being taken (i.e. no tunneling going on).

But remember that visibility is an architectural property, not a
property of any particular application semantic.  Tunneling over POST
breaks the constraints of REST, so it isn't valid to assert that REST
doesn't have superior visibility than "open interface SOAs" because
HTTP POST is tunneled over.

> intermediary has significantly better visibility into an HTTP POST request
> if the contents of the HTTP message contain a SOAP message.

I get the impression that you're focusing primarily on "syntactic
visibility", while I'm talking about "semantic visibility".  Recall the
definition from Roy's dissertation;

"Visibility in this case refers to the ability of a component to monitor
or mediate the interaction between two other components."

That can only happen with a lot more than agreement on syntax.

Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Web architecture consulting, technical reports, evaluation & analysis
  Actively seeking contract work or employment
Received on Tuesday, 27 May 2003 15:54:52 UTC

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