W3C home > Mailing lists > Public > www-ws-arch@w3.org > September 2002

Re: Completeness

From: Mark Baker <distobj@acm.org>
Date: Sat, 28 Sep 2002 22:08:53 -0400
To: Jeff Mischkinsky <jeff.mischkinsky@oracle.com>
Cc: www-ws-arch@w3.org
Message-ID: <20020928220853.Z24048@www.markbaker.ca>

On Sat, Sep 28, 2002 at 05:33:34PM -0700, Jeff Mischkinsky wrote:
> All turing equivalent systems CAN be made to do the same thing. It's just a 
> small matter of programming :-). The question is how hard is it. And how 
> usable is the end result. In particular, not all computationally complete 
> systems have the same performance, storage requirements, etc., properties, 
> when applied to a given problem. Your only guarantee is that they will 
> eventually compute the answer.


Have a look at what a solution to a popular Web services problem looks
like when respecting all the REST constraintis.  The scenario is;


and my proposed solution is at the end of;


What kinds of undesirable properties do you think this solution would
yield, compared with the proposed solution in the scenario?

> The way I interpret David's argument is that screen scraping html pages in 
> order to fill in forms, while theoretically achievable by a computationally 
> complete system is "too hard" to do today.

Oh heavens, I'm not suggesting scraping HTML.  I'm suggesting using XML
instead of HTML, or preferably RDF/XML.

> >The BIG "So what?" here, is that this solution on the Web has the same
> >properties that made the Web succeed, because it respects the
> >constraints of the Web that induce those properties.  Since a Web
> >services solution does not, because it does not follow some of those
> >constraints (specifically, uniform interface) it will not share those
> >same properties.
> Logic foul!!!
> p=respecting all the constraints
> q=success (has the desired properties)
>    p->q most assuredly does not imply ~p -> ~q (except in advertising:-)

Correct, but I wasn't implying that there is only one set of constraints
that will give you the desired properties (though I expect it's true).
I'm claiming that the constraints that define the Web *do* give you
these properties.  In addition, I claim that designing constraints to
achieve a desired set of properties is an extraordinarily difficult
task.  Plus, we're in the W3C, which I feel gives the constraints of the
Web priority.

> I'm just tired of the dogma.

For something to be dogma, it has to be groundless.  Yet the constraints
I speak of are responsible for building the most successful and largest
distributed application on the Internet.  Could anything be further from

I'll give you the benefit of the doubt, and assume you just chose your
words poorly.

Mark Baker, CTO, Idokorro Mobile (formerly Planetfred)
Ottawa, Ontario, CANADA.               distobj@acm.org
http://www.markbaker.ca        http://www.idokorro.com
Received on Saturday, 28 September 2002 22:08:27 UTC

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