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Re: URN as namespace URI for RDF Schema (run away... run away... ;-)

From: Richard Newman <r.newman@reading.ac.uk>
Date: Wed, 6 Oct 2004 23:32:42 +0100
Message-Id: <A31667D0-17E7-11D9-8EEE-000A95D338FC@reading.ac.uk>
Cc: RDF interest group <www-rdf-interest@w3.org>
To: Stephen Rhoads <rhoadsnyc@mac.com>

   This idea (a) hasn't been heavily thought-through (having pretty much 
just jumped into my head), and (b) might have already been suggested, 
but I'll throw it in anyway.
   How about using redirects? The problem is the overloaded use of one 
URI for several things: the returned representation, and the concept 
itself. In this case, it's actually for two representations as well as 
the concept. What we really want is to ask for a representation of the 
concept, and get back a suitable one, in such a way that each 'thing' 
is distinctly identified.

   It strikes me that if I ask for <http://example.com/Stephen>, 
accepting RDF (or with an MGET), then I should be redirected to 
<http://example.com/Stephen/RDF>; if I hit it with a standard GET, I 
should be redirected to <http://example.com/Stephen/image.jpg>. These 
are two separate, unambiguous resources; indeed, they could be formally 
related to the concept:

ex:Stephen ex:rdfRep <http://example.com/Stephen/RDF> ;
            ex:hrRep <http://example.com/Stephen/image.jpg> .
(or somesuch).

   So statements about the concept point to one URI, statements about 
the image use the image URL, and statements about the RDF graph point 
to the RDF. The base URI isn't itself dereferenceable (by which I mean 
a representation is returned for that URI*), but conditionally 
redirects to resources which are, in such a way that it is understood 
by clients. This last bit I see as a stumbling block - how do they 
handle the fact that they've got back a different resource?

   It's late, so apologies if this makes no sense at all!

* Though I suppose that the statements about the base URI could be 
returned by an MGET... a difference between accepting 
application/rdf+xml and MGET?


On Oct 6, 2004, at 20:54, Stephen Rhoads wrote:
> This brings to mind something which I have been struggling over ...
> If one uses MGET (or "Accept: application/rdf+xml") to retrieve an RDF 
> description of a URI for which there is also a representation 
> available via GET (a URL), what is being described, the concept 
> denoted by the URI, or the representation (such as an HTML page) 
> returned when dereferencing the URI?
> If the former, how does one make statements about the representation?  
> If the latter, how does one make statements about the concept?
> Suppose I mint a URI to identify myself and put up an RDF description 
> which is returned to an MGET or when application/xml+rdf is specified. 
>  I then put up an image of myself which is returned to a normal GET.  
> How can I separately make statements about myself (type:Person, 
> name:"Stephen") and about the image (type:Image, aspectRatio:"16:9", 
> mediaType:"image/jpeg")?
> --- Stephen
Received on Wednesday, 6 October 2004 22:33:21 UTC

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