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

From: Mark Birbeck <mark.birbeck@webbackplane.com>
Date: Mon, 14 Jul 2008 10:22:32 +0100
Message-ID: <ed77aa9f0807140222p3783b8d5g5675043474cd7d32@mail.gmail.com>
To: "Tom Heath" <Tom.Heath@talis.com>
Cc: "Kingsley Idehen" <kidehen@openlinksw.com>, public-lod@w3.org, semantic-web@w3.org

Hi Tom,

> 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? Doesn't this RDFa + RDF/XML
> pattern complicate the RDF-consumption picture in general...

It's difficult to answer this definitively. However, one factor to
consider is that the technique you describe was *already* in existence
when work began on RDFa, some four or five years ago. (And, for that
matter, when work began on Microformats, too.)

Given that there were few uses of this technique, outside of
controlled environments, I don't think we can say that RDFa has made
the situation _more_ complicated, or that it will inhibit adoption.

And of course, I'm biased. :)

I would say that RDFa has made the situation an order of magnitude
_less_ complicated, since authors and developers now have an easier
way to publish metadata; as Kinglsey said, increasing the number of
ways to publish metadata increases the number of possible clients that
might consume the data:

>> I also forgot to mention obvous use of RDFa in the HTML doc
>> which broadens the range of rdf aware user agents tha
>> commence RDF discovery from HTML

One more thing on your comments:

> [snip]
> 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?

Is it possible to distinguish a graph URI? I hadn't realised that. It
would certainly be a good idea to  have an rdf:Graph type, but I
hadn't realised that there was one.

However, is not an rdf:Graph a type of information resource? An
RDF/XML document delivered from a web server is both a document and a
graph, but we have chosen to ignore that in the RDF architecture; it's
not possible to say 'this graph was published by', in RDF/XML, i.e.,
to talk about the information resource itself, because you will always
be talking about whatever the RDF/XML itself is about.

But there is no reason that we could not enable this, and if we wanted
to go this route, RDFa+HTML allows it.



Mark Birbeck, webBackplane



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Received on Monday, 14 July 2008 09:23:07 UTC

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