W3C home > Mailing lists > Public > www-tag@w3.org > December 2006

Re: RDDL: new natures

From: Jonathan Borden <jonathan@openhealth.org>
Date: Mon, 11 Dec 2006 10:49:25 -0500
Message-Id: <D28506C6-3455-46E2-9E74-EAFFC2FA37C3@openhealth.org>
Cc: www-tag@w3.org, XML Developers List <xml-dev@lists.xml.org>, Leigh Dodds <leigh@ldodds.com>
To: Elliotte Harold <elharo@metalab.unc.edu>
  Elliotte Harold wrote:

> Jonathan Borden wrote:
>> When I say that the rddl:nature of http://example.org/foo.xsd is  
>> "XML Schema", this is intended to assert that it is reasonable to  
>> assume that http://example.org/foo.xsd ought comply with the "XML  
>> Schema" specification i.e. validate as an "XML Schema".
> I believe this to be sufficiently asserted by xlink:role="http:// 
> www.w3.org/2001/XMLSchema"
>> What I *don't* want to say is that <http://example.org/foo.xsd> is  
>> a member of the XML Schema namespace.
> Good. xlink:role="http://www.w3.org/2001/XMLSchema" does not say that.
> In fact, I'm not sure anything would. URLs and documents are not  
> generally considered to be members of a namespace. The document at  
> http://example.org/foo.xsd could say that the root element is a  
> member of the namespace with a xmlns="http://www.w3.org/2001/ 
> XMLSchema" attribute; but that's a very different thing.
>> Using <http://www.w3.org/2001/XMLSchema> as the URI for the nature  
>> of "XML Schema" creates this ambiguity for ***software agents***.
> In practice XML software agents are indeed smart enough to  
> distinguish between xlink:role="http://www.w3.org/2001/XMLSchema"  
> and xmlns="http://www.w3.org/2001/XMLSchema" and even  
> xlink:href="http://www.w3.org/2001/XMLSchema". I don't think  
> there's any ambiguity here we need to worry about.

In reconsidering this, and also in light of Leigh's comments, I am  
coming to think that both of you are correct.

My original thinking (which has clouded my own understanding of this  
issue) was that the use of RDDL Nature (xlink:role) was equivalent to  
asserting an <rdf:type> between the related resource and the nature  
URI. This was in accordance with Ron Daniel's W3C Note on Harvesting  
RDF statements from XLink http://www.w3.org/TR/xlink2rdf/ ,  
informative reference 9.2 in the RDDL spec.

On the other hand Norm Walsh provides an alternate view in http:// 
www.w3.org/2001/tag/doc/nsDocuments/ specifically the "RDDL Model for  

If we adopt this model (NDW/TAG) then there is no real problem using  
a namespace URI as the rddl:nature. (rddl:nature is now a plain 'ole  

So what I currently propose is that we continue to allow/recommend  
RDDL Natures like http://www.w3.org/2001/XMLSchema *and* that we  
change the documentation (and rddl2ref.xsl) to reflect the model  

Received on Monday, 11 December 2006 15:49:53 UTC

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