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Re: [ALL] RDF/A Primer Version

From: Ben Adida <ben@mit.edu>
Date: Tue, 31 Jan 2006 13:02:30 -0500
Message-Id: <C3915BD4-69E9-4032-B823-5EC6CD53557A@mit.edu>
Cc: "Booth, David (HP Software - Boston)" <dbooth@hp.com>, "Miles, AJ (Alistair)" <A.J.Miles@rl.ac.uk>, SWBPD list <public-swbp-wg@w3.org>, public-rdf-in-xhtml task force <public-rdf-in-xhtml-tf@w3.org>, Pat Hayes <phayes@ihmc.us>
To: Jeremy Carroll <jjc@hpl.hp.com>

Continuing on this point, I guess that implies the following thing:

If http://example.com/foo resolves to an XHTML document, then http:// 
example.com/foo#bar can only be an information resource. However, if  
http://example.com/foo resolves to an N3 document, then http:// 
example.com/foo#bar *can* be an information resource, because there  
is no way to get a fragment of an N3 document.

The first consequence is that XHTML documents are somehow second- 
class citizens to N3 in expressing semweb statements. That would be  
truly unfortunate.

The second consequence is that the RDF type of a frag URI now depends  
on the Mime Type of the non-frag URI. That seems bad, too.


On Jan 31, 2006, at 12:50 PM, Jeremy Carroll wrote:

> It is of course conceivable that we are identifying a bug with the  
> web architecture document rather than a bug in our use of URIs.
> The space of URIs available for non-Information resources seems to  
> be getting smaller and smaller, soon the Semantic Web will be  
> disallowed by the Web Architecture document.
> Jeremy
> Booth, David (HP Software - Boston) wrote:
>>> From: Miles, AJ (Alistair) [mailto:A.J.Miles@rl.ac.uk]
>>> I think that, because no element with the id attribute value "me"  
>>> is actually present in the document, then current specifications  
>>> [3,4] do not allow any conclusions about the nature of <#me> to  
>>> be drawn from the content-type of the document.
>> I don't think that's quite correct.  The WebArch makes no requirement
>> that the fragment identifier actually exist in the retrieved  
>> document.
>> The dependency is on whether a *representation* exists when the  
>> primary
>> resource is dereferenced.  From WebArch sec 3.2.1:
>> [[
>> The semantics of a fragment identifier are defined by the set of
>> representations that might result from a retrieval action on the  
>> primary
>> resource. The fragment's format and resolution are therefore  
>> dependent
>> on the type of a potentially retrieved representation, even though  
>> such
>> a retrieval is only performed if the URI is dereferenced. If no such
>> representation exists, then the semantics of the fragment are  
>> considered
>> unknown and, effectively, unconstrained.
>> ]]
>> Thus, my interpretation of the WebArch is that if http:// 
>> example.org/foo
>> returns application/xhtml+xml, then RFC3236 applies, which states:  
>> 	". . . fragment identifiers for XHTML documents designate 	the  
>> element with the corresponding ID attribute value".  If no such  
>> element exists, then http://example.org/foo#me identifies a
>> non-existent element.  The fact that no such element actually exists
>> does not change the fact that that is what the URI identifies.
>>> . . .
>>> Please note my position given at [7]: 'I support publication of  
>>> this document as a Working Draft'. I do not think the publication  
>>> of RDF/A as Working Draft should be delayed because of this  
>>> particular discussion thread.
>> I agree.  I think the warning that Ben has added is adequate.
>> David Booth
>>> [3] http://www.w3.org/TR/2004/REC-webarch-20041215/#media-type- 
>>> fragid
>>> [4] http://www.ietf.org/rfc/rfc3236.txt
>>> [5] http://lists.w3.org/Archives/Public/public-swbp-wg/2006Jan/ 
>>> 0152.html
>>> [6] http://lists.w3.org/Archives/Public/public-swbp-wg/2006Jan/ 
>>> 0153.html
>>> [7] http://lists.w3.org/Archives/Public/public-swbp-wg/2006Jan/ 
>>> 0113.html
Received on Tuesday, 31 January 2006 18:02:42 UTC

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