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Re: rdf-ns-prefix-confusion

From: Uche Ogbuji <uche.ogbuji@fourthought.com>
Date: Thu, 10 Jan 2002 08:55:56 -0700
Message-Id: <200201101555.g0AFtuC07015@localhost.localdomain>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
cc: "Uche Ogbuji" <uche.ogbuji@fourthought.com>, "www-rdf-interest" <www-rdf-interest@w3.org>
> 
> I was not in the WG at the time the decision was made. But seeing no other
> reply I will have a go.
> 
> 
> If unqualified attributes are allowed then there is a specific problem with
> cases where the element is not qualified in the RDF namespace.

Unqualified attributes should only be allowed on elements that *are* in the 
RDF namespace.  This is the XSLT approach (see literal result element as 
stylesheet, in particular)

So, no more problem, yes?


> In the other standards you mention, I believe that unqualified attributes
> are used on elements that themselves belong to the standard's own reserved
> namespace.
> 
> Hence, I think there was a problem with M&S and four possible solutions:
> 
> A: all attributes must be qualified
> B: attributes of elements in the rdf namespace need not be qualified,
> attributes of other elements should always be qualified

This is the solution I'm advocating.


> C: the reserved attribute names in an RDF/XML document always have their
> special meaning, whatever the namespace of the element.

Oh, but this would be beyond horrible.


> B and C both seem to be in tension with the XML Namespace spec.

I don't see how B does.


> Unqualified
> attributes do not share the namespace of their element.

Why must they?  XInclude attrs, for instance, are not in the XLink namespace 
from the Infoset POV, but XInclude processors recognize the attributes from 
their owner element.  You are similarly free to pile on your own attrs, if you 
like, but they *must* be qialified:

<xi:include href="foo.xml" parse="text" my:extattr="spam"/>

I see no reason why this solution is not fit for RDF: RDF processors will have 
to be at least as sophisticated as XInclude processors, I would think.


> Whereas B would
> equate an ID attribute on an rdf:Description element with an rdf:ID on a
> foo:bar element.

Yes it would.  And this does not violate anything in the namespace REC by 
itself.  The RDF/XML syntax would need slightly new wording, but that should 
hardly be a problem.  I have to run now, so I'll draft an example this 
afternoon.


> C conversely would suggest that RDF/XML can define the
> semantics of an attribute which modifies something not in its namespace.

I'm not sure how C could ever come into sane contemplation.  ;-)

Thanks for the response.


-- 
Uche Ogbuji                               Principal Consultant
uche.ogbuji@fourthought.com               +1 303 583 9900 x 101
Fourthought, Inc.                         http://Fourthought.com 
4735 East Walnut St, Boulder, CO 80301-2537, USA
XML strategy, XML tools (http://4Suite.org), knowledge management
Received on Thursday, 10 January 2002 10:58:16 GMT

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