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RE: Can RDF thrive in an XML-centric world?

From: Danny Ayers <danny666@virgilio.it>
Date: Sat, 2 Nov 2002 01:22:41 +0100
To: "Bob MacGregor" <macgregor@ISI.EDU>, "Dan Brickley" <danbri@w3.org>, <www-rdf-interest@w3.org>
Message-ID: <EBEPLGMHCDOJJJPCFHEFGENAIEAA.danny666@virgilio.it>


> >Our main feature this week on XML.com is from well-known XML
> >experts Bob DuCharme and John Cowan.  In "Make Your XML
> >RDF-Friendly" they describe how to structure XML documents so
> >that they can be used by RDF processors.
>
>Very nice article.  However, I was hoping to read some do's and don'ts
>for structuring XML so that an XML-to-RDF converter could do a good
>job of converting the XML into RDF.  What I think the authors were
>describing
>is how to structure your XML so that a standard RDF parser could
>read it successfully.  Some of the advice was innocuous: how to
>include URI references in a compatible way.  But then they started
>advocating insertion of RDF-syntax (as opposed to RDF-style).  The
>ugly RDF:resource tag was recommended.

Hmm - well it appears more like how to make your data *be* RDF, rather than
just RDF-friendly. I wonder how far towards their  respective cheeks the
good gentlemens' tongues were... It's certainly a good article, and those 8
points make a pretty good best-practice checklist for anyone going anywhere
near RDF.

And then "striping".  RDF
>striping is an unfortunate hang-over from the bad old days that ought
>to be declared deprecated.

I'm sorry, have I missed something here? Apart from being perhaps a little
too XML-like in appearance (thus risking misinterpretation by humans), my
impression of the striping was that it was actually a thoroughly handy
technique.

Expecting that XML users will refactor
>their XML to conform to obscure RDF conventions strikes me as
>dangerously naive (dangerous to the future health of RDF).

I'm not sure about this - if you rephrase that to 'represent their data so
that it conforms to RDF conventions', it starts to sound very important (in
a positive sense) to the health of RDF. That a lot of existing XML users
might resist such a suggestion would I suppose be a good case in favour of
articles like the one in question.

>IMHO the RDF world should be learning how to
>accomodate the XML world, not the other way around.  The core good ideas in
>RDF are URI's and triples (while current RDF syntax is a huge liability).
>If something in XML can't be converted into triple form,
>then we have a problem that needs to be handled one way or another.

I think my list of core good ideas in RDF would be somewhat longer, in this
context I would definitely include the graph model, further up the list than
triples. All the same I don't deny that the ability to represent the graph
in triples is a piece of magic.

>If someone were to write an triple-compatibility verifier for XML that
>indicates how successfully a given piece of XML might be converted into
>RDF triples, that would be a nice contribution towards a future tool suite
>intended to provide a robust means for importing XML into RDF
>triple stores
>(perhaps
>by-passing RDF syntax completely).

The problem here isn't really the transformation validity, as one could for
instance use something like the Infoset RDF Schema [1] to convert any XML to
RDF in a reasonably robust fashion. The transformation from (messy) tree to
(bitty) graph is relatively straightforward, but following a topological
approach can make for pretty convoluted semantic mappings. There may also be
potential problems with transformations that don't 'understand' the model,
in the same way that a dedicated XML parser is usually to be preferred over
a regexp hack - things can spill over the sides.

The critical piece IMHO is how well the model behind the data (*before* it
gets converted to XML) maps to an RDF graph. Ok, so a lot of people might be
drawn into the fold if there were nice simple XML to RDF tools, (which <!--
stretch --> isn't much of a different situation than a year or two back with
RDBMS and XML). But perhaps also there may be opportunity to go for the
jugular, with an RDF-modelled database which could supplant RDBMS/XMLDBs
(TAP?). The producers of the 'Sentences' [2] database make some bold claims
with regard to efficiency in modelling and performance for traditional DB
jobs, and their model is noticeably similar to RDF.
[drifts off into late night ramble-space...]

A suggestion for the authors - perhaps a follow up could describe how RDF
can help with down-the-wire serializations, get some more SOAP folks on
board ;-)

Cheers,
Danny.


[1] http://www.w3.org/TR/xml-infoset-rdfs
[2] http://www.lazysoft.com/
Received on Friday, 1 November 2002 19:33:24 GMT

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