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Re: QName URI Scheme Re-Visited, Revised, and Revealing

From: Sean B. Palmer <sean@mysterylights.com>
Date: Thu, 23 Aug 2001 15:45:59 +0100
Message-ID: <021901c12be2$7128ff40$e9da93c3@Palmer>
To: "David Allsopp" <dallsopp@signal.qinetiq.com>
Cc: <www-rdf-interest@w3.org>
> So, this is all fine if you only use plain XML, where QNames
> matter, and all fine if you only use RDF, where URIs matter.
> The remaining question is whether we are causing ourselves
> problems when we are in both camps, e.g. trying to convert
> plain XML 'legacy' documents into RDF.

You can't really convert "documents" into "data", but you can scrape the
semantics out into RDF, and XSLT is usually the tool of choice for doing
that. DanC et al. have demonstrated using XSLT on the Semantic Web for all
sorts of things [1].

The only reason why you'd want to point at QNames is if you wanted to
annotate them with Dublin Core, and store them in a DLG, for accessibility
reasons, or something like that. And now that we have Patrick's QN URI
scheme, we can do so quite easily!

> For example, lets say we are processing XML files in
> various schemas into one common format; it is possible,
> although unlikely, that we will have QNames from
> different sources that happen to map to the same URI.

Not if you use Patrick's new scheme. Remember, you can't use arbitrary XML
in RDF, because the RDF parser will always parse it as RDF, obliterating
the QNames, and turning them into URI references. To use those QNames, you
have to *convert* that XML instance into data (i.e. resources), which is
just as well because the methods for doing so very from XML language to XML
language. In other words, it depends how you scrape the data: remembering
that different XML languages store data in different places, in different
ways, and this is often unambiguous. RDF was made for the Semantic Web
because it's completely unambiguous when it comes to where the data is
stored and so on.

[...]
> [*] However, I think there may still be a separate problem
> if people choose RDF namespaces without a terminal '#',
> as we can still get unintentional URI clashes on rare
> occasions, if people choose very similar namespaces:
> http://foo.com/discovery + ack
> http://foo.com/discover + yack

No, because RDF has no notion of a "namespace" either. The things above are
geared towards being XML namespaces, and that's fine. But to represent them
as URIs, you'll have to map them onto a URI somehow.

[1] http://www.w3.org/2000/01/sw/

--
Kindest Regards,
Sean B. Palmer
@prefix : <http://webns.net/roughterms/> .
:Sean :hasHomepage <http://purl.org/net/sbp/> .
Received on Thursday, 23 August 2001 10:46:01 GMT

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