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Re: rel=CURIE in RDFa, but rel=URI in Link:

From: Shane McCarron <shane@aptest.com>
Date: Fri, 26 Sep 2008 07:14:53 -0500
Message-ID: <48DCD23D.3040202@aptest.com>
To: Julian Reschke <julian.reschke@gmx.de>
CC: Dan Connolly <connolly@w3.org>, "Henry S. Thompson" <ht@inf.ed.ac.uk>, Jonathan Rees <jar@creativecommons.org>, "www-tag@w3.org WG" <www-tag@w3.org>, XHTML WG <public-xhtml2@w3.org>

Well - I didn't reply because there was not a question.  Since you raise 
it again, however, I will try:

Julian Reschke wrote:
> Shane,
> I noticed that you didn't reply to this email. We discussed this topic 
> shortly on yesterday's HTML5 telco.
> From what I hear it seems your position is that either:
> 1) It's ok for XHTML2 and HTML5 to define conflicting syntax rules for 
> @rel (and potentially @rev).
> 2) It *is* a problem, so HTML5 will need to adapt to what RDFa defines.
> Re 1: that would be a problem; it will make conversion of documents 
> and document fragments much harder, and will create an inconsistency 
> in the DOM.
> Re 2: I doubt that this is going to fly, but if you think this would 
> be the right thing, please raise this point over in the HTML WG.
> BR, Julian
> PS: please note that I'm generally in *favor* of the RDFa approach, 
> and I would like it to be fully adopted in HTML5 (and extensions to 
> HTML4, btw). I just see a problem with introducing plain (non-safe) 
> CURIEs in a place where others already want to use URIs.
I understand what you are saying.  However, I guess my response is that 
I believe the XHTML 2 Working Group has scope in this space explicitly 
by charter.  The group, in conjunction with the Semantic Web Deployment 
Working Group, has defined RDFa and it has gone through the W3C 
process.  It will very soon be a Recommendation.  This Recommendation 
includes an XHTML Module that defines @rel /@rev and a bunch of other 
things, and shows how they integrate with XHTML family markup 
languages.  It says that the lexical space for @rel /@rev is " (reserved 
word | CURIE 
<http://www.w3.org/MarkUp/2008/ED-rdfa-syntax-20080619/#dt_curie>)+" and 
defines the reserved words that are recognized by RDFa processors. If 
someone else wants to extend that, they are going to need to find a way 
to do it that is consistent with this Rec.  If there is no way for that 
to happen, then it is an issue for the Hypertext Coordination Group, the 
TAG, and / or the Director.

As to raising this with the HTML WG, there are representatives of the 
RDFa Task Force who have been doing so for ages in the context of the 
W3C group and the WHATWG.  I personally have stayed out of that 
discussion.  HTML5 is years from adoption, and there is plenty of time 
to iron out wrinkles like these.  If HTML5 is to be a player in the sem 
web community, then it will need to accommodate RDFa.  We have tried 
hard to ensure that this is easy to do.  I hope that we succeeded.  I 
know that we have a proof of concept integration with HTML4 that works 
like a charm.

The main point of this thread was a discussion of whether the Link: 
header extensions for HTTP would conflict with RDFa.  I and the RDFa 
Task Force believe that they do not conflict because the value space of 
CURIE is a superset of the value space for the proposed Link: header 
extensions AND the CURIE value space (IRI) is directly transformable to 
the Link: header value space (URI) as per the relevant RFCs.

Julian Reschke wrote:
> Shane McCarron wrote:
>> FWIW, RDFa is part of the XHTML 2 activity, and DOES own link/@rel.  
>> We believe that the extension of @rel to use CURIE is completely 
>> consistent with the HTTP spec HTTP Link: space. The value space for 
>> CURIE is IRI.  
> I think it's safe to say that there isn't consensus about "who owns 
> the rel attribute" between the XHTML2 and HTML5 working groups. It 
> would be unfortunate if we ended up with different syntax in both 
> languages.
> Furthermore note that the lexical space in the HTTP link header draft 
> is *URI*, not *IRI*. One could argue that this is a problem HTTP needs 
> to solve, but it's worth keeping in mind nevertheless.
>> The lexical space doesn't really matter in this context - since any 
>> processor looking at link / @rel would need the value space version.  
>> What am I missing here?
> Best regards, Julian

Shane P. McCarron                          Phone: +1 763 786-8160 x120
Managing Director                            Fax: +1 763 786-8180
ApTest Minnesota                            Inet: shane@aptest.com
Received on Friday, 26 September 2008 12:22:14 UTC

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