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RE: ISSUE-57: The use of HTTP Redirection

From: Booth, David (HP Software - Boston) <dbooth@hp.com>
Date: Thu, 30 Aug 2007 01:33:05 -0400
Message-ID: <EBBD956B8A9002479B0C9CE9FE14A6C2031D2122@tayexc19.americas.cpqcorp.net>
To: "Richard Cyganiak" <richard@cyganiak.de>
Cc: "Tim Berners-Lee" <timbl@w3.org>, "Ed Davies" <edavies@nildram.co.uk>, "Technical Architecture Group WG" <www-tag@w3.org>, "Rhys Lewis" <rhys@volantis.com>

My answers:

> From: Richard Cyganiak [mailto:richard@cyganiak.de] 
> 
> Rhys and others,
> 
> I'll try to articulate my questions more clearly.
> 
> I assume that X is an information resource, such as "Tim's 
> homepage",  
> and that different people can allocate different URIs <x1>, 
> <x2>, ...  
> to identify that resource (e.g. to make RDF statements about it),  
> without necessarily knowing about each other.
> 
> 1. *MUST* the owner of each <xi> configure it to answer 
> requests with  a 200 and a representation?

No.

> 
> 2. Or *MAY* they answer requests to <xi> also with 404 or 303?

Yes.

> 
> 3. Assuming there is reason to believe that other people have minted  
> <x1> and <x2> already, and serve representations there: Does WebArch  
> in any way constrain what the owner of <x3> can serve as a  
> representation of X at <x3>?

No.  This answer may seem odd, since you stipulated that <x1>, <x2> and
<x3> identify the *same* resource.  But since the Request-URI is a part
of the HTTP GET request, the exact same resource could return responses
that vary depending on the Request-URI.

> 
> 4. What if the owner of <x3> is legally prohibited from serving  
> representations of X, e.g. by copyright law? Can they still mint  
> their own URI for X? How would they configure it?

I don't understand this question.  Yes, they can still mint their own
URI for X, but presumably they would still be prohibited from serving
representations.  Minting a URI does not necessarily mean that any
server is configured.  It just means that the URI owner has associated
that URI with a resource, and "associated" does not mean that the
resource is necessarily accessible, even if it is an information
resource.

> 
> 5. Assuming X is "Tim's homepage", is there a process (technical or  
> social) that allows me to determine if <x1> does identify X, 
> assuming  
> that <x1> 200-responds with a certain representation "abc"?

Not a guaranteed process.  The WebArch gives the URI owner the right to
associate a URI with a resource.  Therefore, if the URI owner declares
that <x1> identifies X, then that declaration is prima facie evidence
that the URI does identify X (as a performative speech act), so under
normal circumstances, one should assume that it does.

> 
> 6. Assuming X is "Tim's homepage", is there a process (technical or  
> social) that allows me to determine if <x2> does identify X, 
> assuming  that <x2> 404-responds?

Same answer as for #5.  A 404 gives no information.

> 
> 7. Assuming X is "Tim's homepage", is there a process (technical or  
> social) that allows me to determine if <x3> does identify X, 
> assuming that <x3> 303-redirects to <y3>?

Same answer as for #5.  A 303 is merely a hint of where to look.  You
might find a URI declaration there, but you might not.



David Booth, Ph.D.
HP Software
+1 617 629 8881 office  |  dbooth@hp.com
http://www.hp.com/go/software

Opinions expressed herein are those of the author and do not represent
the official views of HP unless explicitly stated otherwise.
 
Received on Thursday, 30 August 2007 05:34:10 GMT

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