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Re: WS-Addressing and URIs

From: Dan Connolly <connolly@w3.org>
Date: Mon, 30 Aug 2004 14:05:38 -0500
To: Mark Baker <distobj@acm.org>
Cc: www-tag@w3.org, Hugo Haas <hugo@w3.org>
Message-Id: <1093892737.2934.9355.camel@dirk>

On Mon, 2004-08-30 at 09:50, Mark Baker wrote:
> Hi all,
> 
> I believe there to be a rather large Web-architectural flaw with the
> recent WS-Addressing submission[1] that I wanted to raise with the TAG.

I'd expect you to bring it to the attention of the TAG if you want
one of the TAG's documents changed. I don't see in your message
any request to change a TAG document or even to write a new one.

Am I missing something?

Where does the WS-Addressing submission direct feedback? Hmm... I don't
see anything in the SOTD except the generic link to the list
of acknowledged submissions... if you know enough to look for it,
you can find the team comment, where Hugo writes...

"Feedback on this technology is encouraged on the www-ws@w3.org mailing
list (public archive)."
  -- http://www.w3.org/Submission/2004/05/Comment


> The spec itself covers a lot of ground, but I'm primarily interested in
> section 2[2], "Endpoint References".  As you might expect from the use
> of the word "reference" (and even the title of the spec, "addressing"),
> there is considerable overlap with URIs.  More specifically, what the
> WS-Addressing spec appears to be doing is actually *discouraging* the
> use of URIs for identification, and instead replacing them with an XML
> document (the EPR).  Consider the following example[3] of such a
> document;
> 
> <wsa:EndpointReference xmlns:wsa="..." xmlns:fabrikam="...">
>    <wsa:Address>http://www.fabrikam123.example/acct</wsa:Address>
>    <wsa:ReferenceProperties>
>        <fabrikam:CustomerKey>123456789</fabrikam:CustomerKey>
>    </wsa:ReferenceProperties>
>    <wsa:ReferenceParameters>
>        <fabrikam:ShoppingCart>ABCDEFG</fabrikam:ShoppingCart>
>    </wsa:ReferenceParameters>
> </wsa:EndpointReference>
> 
> In that example, the URI "http://www.fabrikam123.example/acct" is used
> to identify a "gateway" of sorts, beyond which one is left requiring the
> use of the CustomerKey value for the actual identification of the
> customer account resource.  Can any of the WS-Addressing submitters
> explain why the customer account isn't just identified by a URI such as
> this one?
> 
>   http://www.fabrikam123.example/acct/123456789
> 
> (I'm ignoring the reference parameter there for the moment since it's
> role is slightly different than the property, and should not, arguably,
> be part of the URI)
> 
> If the issue here is that Web services needs to license a client to
> peek into an identifier (which seems to be the case, otherwise why
> would you standardize it?), I would recommend that they define a new
> URI scheme, say, "epr".  This would at least be consistent with the
> webarch good practice item[4] which states;
> 
> "Agents making use of URIs SHOULD NOT attempt to infer properties of the
> referenced resource except as specified by relevant specifications."
> 
> But on the other hand, I don't see why this licensing is required, and
> therefore why a relatively opaque http URI wouldn't suffice.
> 
> Thanks.
> 
>  [1] http://www.w3.org/Submission/2004/SUBM-ws-addressing-20040810/
>  [2] http://www.w3.org/Submission/2004/SUBM-ws-addressing-20040810/#_Toc77464317
>  [3] http://www.w3.org/Submission/2004/SUBM-ws-addressing-20040810/#_Toc77464320
>  [4] http://www.w3.org/TR/webarch/#pr-uri-opacity
> 
> Mark.
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Monday, 30 August 2004 19:05:01 GMT

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