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Re: IRI vs. URI Reference in RDFa

From: Mischa Tuffield <mischa.tuffield@garlik.com>
Date: Fri, 20 May 2011 10:50:11 +0100
Cc: RDF Working Group <public-rdf-wg@w3.org>
Message-Id: <2A4B8494-6B0C-4936-9D4E-65934637E8C3@garlik.com>
To: Manu Sporny <msporny@digitalbazaar.com>
Hello, 

On 19 May 2011, at 06:33, Manu Sporny wrote:

> BCC-cross-posted to: SWCG, RDFa WG
> 
> There is an RDF/RDF Web Apps/RDFa coordination issue that the RDF Web
> Apps group needs to have resolved in order to take RDFa Core 1.1 and
> XHTML+RDFa 1.1 into Candidate Recommendation. We are requesting input
> from RDF WG and coordination help from SW CG
> 
> The basic question is what should an RDFa processor do when it comes
> across a value in an HTML document that looks like this:
> 
> <a rel="foaf:homepage"
>   href="http://www.schweizer-küche.de/">Schweizer Küche</a>
> 
> The issue is being tracked here (raised by Mischa):
> 
> http://www.w3.org/2010/02/rdfa/track/issues/87

I pointed out that the spec should be talking about the modern IRIs as apposed to the URIRef (which was attempting to guess what the IRI spec was going to be). So, yes, it is great news that the RDFa WG is going for IRIs. 

> 
> We had a very long conversation about it on the telecon last week:
> 
> http://www.w3.org/2010/02/rdfa/meetings/2011-05-12#ISSUE__2d_87__3a__IRI_vs__2e__URI_References
> 
> So the question is whether or not the markup above should generate this:
> 
> <> foaf:homepage <http://www.schweizer-küche.de/> .
> 
> or should generate this:
> 
> <> foaf:homepage <http://www.xn--schweizer-kche-qsb.de/> .
> 
> There were good arguments both ways, but I believe that the RDFa WG
> settled on the RDFa processor not modifying the URL value when
> generating the triples for two reasons:
> 
> 1) Punycoding URLs could change the meaning of the triple such that
>   matching rules written by the author would no longer match.
> 2) Punycoding URLs are culturally imperialistic - most of the world's
>   primary languages cannot be expressed in ASCII, we shouldn't
>   force punycoding on all languages "other than English".
> 3) Modifying URLs away from the authors intent, or away from well-known
>   transforms like relative-IRI to absolute-IRIs or normalized
>   IRIs, is bad. We shouldn't attempt to guess what the author meant.
> 4) IDN is a hack and should be dragged into the street and shot
>   (ok, so this is just my opinion :P)
> 
> So the general assertion is that RDFa Processors should only perform the
> following transformation on IRIs:
> 
> 1. Relative to Absolute IRI transformation.
> 
> That is, they shouldn't punycode and they shouldn't attempt to do any
> other processing on the IRI output by the processor. In other words,
> RDFa Processors shouldn't second-guess the document author. Thoughts?
> 
> -- manu
> 
> PS: This also, tangentially, re-opens the can of worms on equivalence
> testing for IRIs in RDF. Is http://example.com/ros&#xE9 the same as
> HTTP://example.com/ros%C3%A9 for equivalence testing in RDF?
> 
> -- 
> Manu Sporny (skype: msporny, twitter: manusporny)
> President/CEO - Digital Bazaar, Inc.
> blog: PaySwarm Developer Tools and Demo Released
> http://digitalbazaar.com/2011/05/05/payswarm-sandbox/
> 
> 

___________________________________
Mischa Tuffield PhD
Email: mischa.tuffield@garlik.com
Homepage - http://mmt.me.uk/
+44(0)208 439 8200  http://www.garlik.com/
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