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Re: WSA constraints

From: Mark Baker <distobj@acm.org>
Date: Mon, 23 Sep 2002 12:03:55 -0400
To: Anne Thomas Manes <anne@manes.net>
Cc: www-ws-arch@w3.org, mark.baker@sympatico.ca
Message-ID: <20020923120355.M8274@www.markbaker.ca>

Anne, thanks for the technical feedback!

On Mon, Sep 23, 2002 at 10:41:09AM -0400, Anne Thomas Manes wrote:
> I disagree. I don't think the *architecture* is constrained by the
> capabilities of SOAP 1.1 and WSDL 1.1.

I believe that the software is primarily where you have to look in
order to be able to find out what the architecture is.  But since that
software is written to conform to specifications, then some of the
constraints of that architecture can be extracted by looking at the
specs.  I think we was demonstrated this during the harvesting effort.

So the specs aren't authoritative, but they can be suggestive.

> I also don't agree with your list of "constraints".
> 
> In particular, I doubt think that the architecture is not constrained to
> client/server. Most people use Web services within the constraints of the
> client/server pattern, but does the architecture constrain it that way?

I believe so.  But recall my previous comments about how the term
"client/server" is often misunderstood - or, perhaps more accurately
stated, means different things in different contexts;

http://lists.w3.org/Archives/Public/www-ws-arch/2002Sep/0030

> Doesn't the architecture also support peer-based messaging?

Yes, as a special case of client/server, where a component
simultaneously supports both the client and server role.

> I agree that the Web services architecture relies on / exploits "layering".
> Does that constitute a "constraint"? (Constraint implies limitation. The way
> Web services uses layering removes limitations.)

In this context, "constraint" doesn't suggest a limitation of function,
only a limitation of form (in case you thought the former).  They are
GoodThings(tm). 8-)

I did think about this for a while, and could have gone either way, but
SOAP's processing model is explicitly layered, so that convinced me that
it was a reasonable constraint.  I could be convinced otherwise,
however, since few (if any) Web services use SOAP intermediaries.

> I agree with Dave that XML messaging is a constraint. Web services
> participants communicate by passing XML messages. If two applications
> communicate using anything other than XML messages, then they are not using
> the Web services architecture.

Not even GET? Just kidding 8-).  I'm ok with that constraint, because
existing Web services, and SOAP 1.1, don't support GET, just pure XML.
Maybe we'll have to adjust this in the future, when accounting for
SOAP 1.2 based Web services.

MB
-- 
Mark Baker, CTO, Idokorro Mobile (formerly Planetfred)
Ottawa, Ontario, CANADA.               distobj@acm.org
http://www.markbaker.ca        http://www.idokorro.com
Received on Monday, 23 September 2002 12:04:00 GMT

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