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Fwd: Other issues - RDFa Core 1.1 IRIs vs URIRefs

From: Ivan Herman <ivan@w3.org>
Date: Thu, 10 Mar 2011 19:07:07 +0100
Message-Id: <6D1D46B8-93B9-44E7-8139-396B7E6A8D73@w3.org>
Cc: Mischa Tuffield <mischa.tuffield@garlik.com>
To: Shane P McCarron <shane@aptest.com>, W3C RDFa WG <public-rdfa-wg@w3.org>

Misha is on the RDF Working Group where we had a discussion on the URI vs IRI issue. He reviewed the Core spec; here is his review v.a.v this stuff.

Opinions?

Ivan
----
Ivan Herman
Tel:+31 641044153
http://www.ivan-herman.net



Begin forwarded message:

> From: Mischa Tuffield <mischa.tuffield@garlik.com>
> Date: 10 March 2011 18:11:31 CET
> To: Ivan Herman <ivan@w3.org>
> Cc: Manu Sporny <msporny@digitalbazaar.com>
> Subject: Re: Other issues - RDFa Core 1.1 IRIs vs URIRefs 
> 

> Hi Ivan/Manu, 
> 
> Sorry for top-posting. The relevant bit of the below thread is when Ivan said to me : 
> 
>> Actually... there is a revision coming on RDFa. What you should look at, if you can, is 
>> 
>> http://www.w3.org/2010/02/rdfa/sources/rdfa-core/Overview-src.html
>> 
>> which is the editor's draft of what will soon be a 2nd last call document for RDFa 1.1. It would be great if you could look at it with a fresh eye with this issue in your mind...
> 
> 
> I have had a look at the RDFa 1.1 [1] as asked and have made an observation wrt to how URIs are defined in the document. If you feel like I should be sending this to the public-rdfa-wg mailing list do let me know, and/or do feel free to forward accordingly. 
> 
> In short, it seems like RDFa Core 1.1 [1] uses IRIs as defined in RFC3987[2], URIs as per RFC3986 [3], and mentions "URI references" (which is the RDF world is defined as an extension to RFC2396 [4] in the abstract syntax document [5]) which is slightly confusing and maybe even a bug (from my POV anyways).
> 
> 
> **So in Section 2 and Section 7.4 of the document describes URIs in terms of RFC3986. 
> 
> **Section 3.3 - URI references - states: 
> 
> "RDF solves this problem by replacing our vague terms with URI references."
> 
> Note that "URI references" is not defined in this section. 
> 
> and subsequently in Section 3.10 - A description of RDFa - states: 
> 
> "The subject node is always either a URI reference or a blank node (or bnode), the predicate is always a URI reference, and the object of a statement can be a URI reference, a literal, or a bnode." which points back to Section 3.3 (as far as I can tell). 
> 
> ** Section 3.8 - Compact URI Expression - states : 
> 
> "RDFa allows the contraction of most URI references into a form called a 'compact URI expression" <-- I am not sure which URI reference is mentioned here. 
> 
> ** Section 6 - CURIE Syntax
> 
> Defines URIs as per RFC3987 (which are IRIs) and states : 
> 
> "When expanded, the resulting URI must be a syntactically valid URI [RFC3987]. " 
> 
> **And finally, it seems that in section 7.4 CURIE and URI Processing, there is pointers to the IRI spec, RFC3987 which states how relative URIs are resolved wrt to the documents base URI. 
> 
> From my POV this is confusing, and given that SPARQL are using IRIs (RFC3987), and that the Turtle will probably be defined using IRIs, and *hopefully so will RDF/XML via RDF Abstract Syntax document update, I do feel strongly that RDFa should use the newer IRI definition in all places in the RDFa spec. (Again, please do let me know if you think I am wrong here). 
> 
> Warmest Regards, 
> 
> Mischa 
> 
> [1] http://www.w3.org/2010/02/rdfa/sources/rdfa-core/Overview-src.html 
> [2] http://www.ietf.org/rfc/rfc3987.txt 
> [3] http://www.ietf.org/rfc/rfc3986.txt 
> [4] http://www.ietf.org/rfc/rfc2396.txt 
> [5] http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#dfn-URI-reference 
> 
> 
> 
> On 10 Mar 2011, at 09:42, Ivan Herman wrote:
> 
>> Mischa,
>> 
>> On Mar 9, 2011, at 19:54 , Mischa Tuffield wrote:
>> <snip/>
>>> 
>>>> 
>>>> 
>>>>> 2) And whether or not the RDFa spec[1] is in or out of scope of this working group, as it is not listed in the charter as one of the documents which the group will be looking to update[1]? The reason I mention this is again, if we end up in a world where both SPARQL and RDF (lets say the Turtle serialisation) are using IRIs, developers would have to use a different URI encoding library for SPARQL & Turtle, from the one they would be using if there were to be serialising to RDFa. 
>>>>> 
>>>> 
>>>> RDFa is certainly not in the scope of this group, there is a separate group for that one. That being said, afaik RDFa already uses IRIs, just like SPARQL. I explicitly copy this mail to Manu, who is the chair of that group.
>>> 
>>> Thanks, and yes I am aware that Manu is the chair of that group. I need to read the entirety of the RDFa rec [1], but it seems like the only place that IRIs are mentioned are in the CURIE section [2], and the rest of the document including [2] talks about URI References and not IRIs. 
>>> 
>> 
>> Actually... there is a revision coming on RDFa. What you should look at, if you can, is 
>> 
>> http://www.w3.org/2010/02/rdfa/sources/rdfa-core/Overview-src.html
>> 
>> which is the editor's draft of what will soon be a 2nd last call document for RDFa 1.1. It would be great if you could look at it with a fresh eye with this issue in your mind...
>> 
>> Thanks
>> 
>> Ivan
>> 
>>> But, ok, I now understand that RDFa is not in the scope of this group, thanks for the clarification. 
>>> 
>>> [1] http://www.w3.org/TR/rdfa-syntax/
>>> [2] http://www.w3.org/TR/rdfa-syntax/#s_curies 
>>> [3] http://www.w3.org/TR/rdfa-syntax/#sec_3.10. 
>>> 
>>>> 
>>>> Note, however, that RDFa is a bit special in the sence that it "lives" in another environment, namely HTML, which it cannot fully control...
>>> 
>>> Understood. 
>>> 
>>> Regards, 
>>> 
>>> Mischa
>>> 
>>>> 
>>>> Cheers, 
>>>> 
>>>> Ivan
>>>> 
>>>> 
>>>> 
>>>>> Regards, 
>>>>> 
>>>>> Mischa *goes off to look into the back-compatibility of URIRefs to IRIs (any pointers existing work comparing the definitions would be much appreciated)
>>>>> 
>>>>> [1] http://www.w3.org/TR/rdfa-syntax/
>>>>> [2] http://www.w3.org/2011/01/rdf-wg-charter#deliverables 
>>>>> [3] http://www.w3.org/TR/rdfa-syntax/#T_URI_reference 
>>>>> 
>>>>> ___________________________________
>>>>> Mischa Tuffield PhD
>>>>> Email: mischa.tuffield@garlik.com
>>>>> Homepage - http://mmt.me.uk/
>>>>> Garlik Limited, 1-3 Halford Road, Richmond, TW10 6AW
>>>>> +44(0)845 652 2824  http://www.garlik.com/
>>>>> Registered in England and Wales 535 7233 VAT # 849 0517 11
>>>>> Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10 9AD
>>>>> 
>>> 
>>> ___________________________________
>>> Mischa Tuffield PhD
>>> Email: mischa.tuffield@garlik.com
>>> Homepage - http://mmt.me.uk/
>>> Garlik Limited, 1-3 Halford Road, Richmond, TW10 6AW
>>> +44(0)845 652 2824  http://www.garlik.com/
>>> Registered in England and Wales 535 7233 VAT # 849 0517 11
>>> Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10 9AD
>>> 
>> 
>> 
>> ----
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> mobile: +31-641044153
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf
>> 
>> 
>> 
>> 
>> 
> 
> ___________________________________
> Mischa Tuffield PhD
> Email: mischa.tuffield@garlik.com
> Homepage - http://mmt.me.uk/
> 

Received on Thursday, 10 March 2011 18:05:19 UTC

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