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Re: RDFa + RDF/XML Considered Harmful? (was RE: Ordnance Survey data as Linked Data)

From: Richard Cyganiak <richard@cyganiak.de>
Date: Mon, 14 Jul 2008 11:32:09 +0100
Cc: "Kingsley Idehen" <kidehen@openlinksw.com>, <public-lod@w3.org>, <semantic-web@w3.org>
Message-Id: <4E89BE95-D471-4EDF-A22E-06B33B7564DB@cyganiak.de>
To: "Tom Heath" <Tom.Heath@talis.com>

On 14 Jul 2008, at 09:55, Tom Heath wrote:
> Question: is it worth creating a duplicate RDF graph by using RDFa in
> HTML documents, when there is also RDF/XML available just one <link
> rel=".../> away, and at a distinct URI?

I don't know. On first impression, it doesn't seem very useful to  
simply duplicate the triples. Seems like it could be a maintenance/ 
publishing headache.

> Doesn't this RDFa + RDF/XML
> pattern complicate the RDF-consumption picture in general if we assume
> agents will want to do something with data aggregated from a number of
> sources/locations, i.e. doesn't it increase the cost of removing
> duplicate statements by creating more in the first place?

Yes, good point.

There might be some simple ways around this, e.g. if we follow a  
rel="alternate" link from an HTML page to an RDF document, we might  
use the HTML page's URI as the provenance (named graph) of the triples  
parsed from the RDF document, since it's just an alternate variant of  
the same page.

But yes, it complicates the picture.

> Does it not
> also complicate the picture of making provenance statements using  
> named
> graphs, if the subject of the triple could be both an HTML document  
> and
> an RDF graph?

I don't think this is a problem. For provenance purposes, whatever  
works for RDF/XML documents will also work for HTML+RDFa documents.  
Just think of RDFa as a very verbose RDF syntax that contains a lot of  
“comments” (the non-RDF, pure-HTML parts of the document). In the end,  
an RDF agent just sees triples, no matter if they are parsed out of an  
HTML+RDFa document or an RDF/XML document.


> Dunno the answers to these questions, but interested to hear what  
> people
> think.
> Tom.
> -- 
> Tom Heath
> Researcher
> Platform Team
> Talis Information Ltd
> T: 0870 400 5000
> W: http://www.talis.com/platform
Received on Monday, 14 July 2008 10:32:59 UTC

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