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Re: Q to implementers: Resource identifiers - XML Names and/or(concatenated) URIs? (was RE: rdfs.isDefinedBy...)

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Wed, 12 Jun 2002 10:25:55 +0300
To: <jeremy@jeremygray.ca>, "'ext Thomas B. Passin'" <tpassin@comcast.net>, RDF Interest <www-rdf-interest@w3.org>
Message-ID: <B92CD233.1689A%patrick.stickler@nokia.com>

On 2002-06-11 16:59, "ext Jeremy Gray" <jeremy@jeremygray.ca> wrote:

> (from Thomas)
>>> I do agree with you this far - it ought to be possible to avoid using
> XML
>>> namespaces and prefixes in RDF/XML syntax if you want to.
> 
> (from Patrick)
>> Yes, that would be better than nothing, and would also provide
>> for a sort of imperfect round-tripping where qnames are mapped
>> to URIs in the graph and output then only as URIs -- though that
>> might also lead to alot of user confusion since the input/output
>> will not be syntactically identical (even though it will be
>> semantically identical).
> 
> They would be neither syntactically or semantically identical because the
> resulting URI would bear absolutely no relation to the identity expressed in
> the original qname.

In RDF, it's not meant to.

> A qname represents an identifier formed from a namespace
> and a local part, but not some concatenation thereof. Since this at the core
> of what we've been discussing, perhaps you meant something different from
> what came out in your post?

No. I meant exactly what I said. RDF does not use qnames. It uses
URIs. RDF/XML employs qnames, but not in the same way as other
XML applications. For RDF/XML, the qname is just a syntactic hack.
It's simply a way to get a URI into an XML serialization as an
element or attribute name. RDF does not define any semantic significance
to the qname structure or context -- and simply discards that structure
and context when extracting the URI, which is all RDF cares about.

RDF, quite frankly, is very poorly behaved with regards to its use
of qnames. It disregards much of what is expected of qnames.

That is the crux of the qname to URI mapping issue, IMO. XML folks
honor qnames fully, both their structure and context, because qnames
are the global naming scheme for all XML encoded content. RDF on
the other hand is "faking" qnames just to be able to serialize URIs
in XML, and thus what is percieved to be significant in the qname
(namely the namespace) is completely irrelevant to RDF semantics
and not available to RDF applications.

In RDF/XML, qnames are not *real* qnames. They are just URIs
pretending to be or masquerading as qnames.

<soapbox>
We will never be able to fully reconcile qnames and URIs, nor
should we even bother to try. All we need to do is respect the
full structure and semantics of qnames in our RDF/XML
serialization, and only use URIs in such serializations to
denote resources. 
</soapbox>

This is one of the goals of my recently posted
alternative XML serialization for RDF.

c.f. http://lists.w3.org/Archives/Public/www-rdf-interest/2002Jun/0168.html

Cheers,

Patrick

--
               
Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Wednesday, 12 June 2002 03:21:45 GMT

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