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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: Tue, 15 Jul 2008 12:16:15 +0100
Message-ID: <ed77aa9f0807150416s44286d34n996fe046ebe85e33@mail.gmail.com>
To: "Tom Heath" <Tom.Heath@talis.com>
Cc: "Richard Cyganiak" <richard@cyganiak.de>, public-lod@w3.org, semantic-web@w3.org

Hi Tom,

> Mark, before the claim is completely withdrawn I can't help but add my
> 2p worth... ;) I've got to agree broadly that there are some compelling
> usage scenarios for RDFa, but lets not fall into the trap of assuming
> that RDFa is easy and that RDF/XML is hard. Hugh's scenario, or a RDB
> with D2R server, are nice examples of where simply pumping out RDF/XML
> is nice and straightforward.

Well, I should clarify a couple of things.

I do think that from a syntax point of view, RDFa is an easier route
in to RDF, than RDF/XML. Of course, so is Turtle, N3...in fact
*anything* is an easier route in to RDF than RDF/XML. :)

But I think what we're talking about is how to *publish* RDF, and what
is 'easier' or more difficult will depend on who you are, and what
infrastructure you have in place already.

If you have no infrastructure at all, then publishing RDFa is
obviously easier than publishing RDF/XML, since all you need to do is
get yourself a blog. If you have a bit of infrastructure, and limited
experience, then you could add RDFa to your web-site, so again it's a
little easier.

If you have an RDF back-end, then it's obviously *very* easy to
publish RDF/XML. And of course, if you have experience with data feeds
and the like, then you could easily create an RDF/XML data source
alongside your web-pages.

So I was by no means saying that RDFa is 'easy' and RDF/XML is 'hard'.
But what I am pointing out is that we should see a lot more metadata
on the web in the near future, because it is now possible to publish
it using well established publishing mechanisms.

And I'd imagine that is good news for those desirous of a 'semantic' web.

> As always it's a case of the right tool for the right job.


> Regarding
> your other (admittedly unfounded) claim, there may be many more people
> who end up publishing RDF as RDFa, but collectively they may end up
> publishing far fewer triples in total than a small number of publishers
> with very large data sets who choose to use RDF/XML to expose data from
> backend DBs.

Sure. But there is nothing to say that you can't publish large
datasets using XHTML+RDFa, i.e., producing XHTML+RDFa documents that
are primarily intended for consumption by another server, rather than
a web browser.

Publishers might then choose to publish just one document type,
especially when it can be consumed by search engines like

Once people realise this, it will be interesting to see how much the
RDF/XML format is used, going forwards.

(All unfounded conjecture on my part, of course. :))

> [snip]
>> There is no rdf:Graph type, and Tom didn't say there is one.
>> Tom used the words "RDF document" and "RDF graph"
>> synonymously, which is a bit sloppy.
> Cough. Not strictly true, Richard, although you interpreted my meaning
> correctly; RDF document would have been a better term to use.
> What I was getting at in my original message was the question of whether
> there are different statements we might wish to make about an HTML-only
> document compared to a straight RDF/XML document.

I looked at that in my other email, so won't say more here, since that
thread is still running.



Mark Birbeck, webBackplane



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Received on Tuesday, 15 July 2008 11:16:51 UTC

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