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Re: Proposed issue; Visibility of Web services

From: Mark Baker <distobj@acm.org>
Date: Sat, 31 May 2003 15:55:51 -0400
To: www-ws@w3.org
Message-ID: <20030531155551.G27576@www.markbaker.ca>

On Fri, May 30, 2003 at 05:54:13PM -0600, Champion, Mike wrote:
> > Just some pedantic silliness on a Friday afternoon, in an attempt to
> > explain that encoding messages in URIs is broken.
> Is this a canonical truth of RESTifarianism, a principle of the Web
> architecture, your personal opinion, or what?

Hmm, I didn't realize that would be controversial.  I mean, I think it's
pretty clear that when you take a message and put it in a URI such that
you can invoke GET on it, that whomever you give that URI to doesn't
have to know what the method in the message means, and therefore the
semantic of the exchange has changed.  Hmm..

But yes, I strongly believe that this would be a principle of Web
architecture (though "principle" is quite weakly defined).

> Is this the "opaque URI"
> principle in another guise?  I thought that was controversial even among
> RESTifarians ...

It is related to Tim's "opacity axiom", but only to the RESTful part of
that axiom which says that one need not have any prior knowledge of any
part of a URI in order to invoke GET on it (per the uniform interface
constraint, I think).  The other part of Tim's axiom says that no
information can be gleaned from a URI, which REST doesn't talk about,
but it also doesn't constrain you from inferring structure from "/", for
example, so long as the other constraints are followed while doing so.

Then Chris said;
> Finally, who said that it changes the semantics of the message?!?

The semantics of the SOAP message over HTTP POST is "GetStockQuote",
while the semantics of the SOAP message over HTTP GET is "GET".

Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca
Web architecture consulting, technical reports, evaluation & analysis
  Actively seeking contract work or employment
Received on Saturday, 31 May 2003 15:52:36 UTC

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