Re: .htaccess a major bottleneck to Semantic Web adoption / Was: Re: RDFa vs RDF/XML and content negotiation

Hi Martin,

> Beyond that, RDFa can create code that is very
> hard to maintain. In fact, I know that a large software company
> dismissed the use of RDFa in their products because of the unmanageable
> mix of conceptual and presentation layer.

Now I'm going to sound like I don't believe there are any problems with RDFa.

But... :)

The issue here is not that RDFa forces a mix of conceptual and
presentation layers -- it would be more correct to say that RDFa
_allows_ for a mix of conceptual and presentation layers. But there is
nothing to force that mixing, and RDFa can also be used for different
points along the spectrum.

For example, I could create an RDF schema or OWL ontology using RDFa,
which would be much the same, in terms of verbosity, as an RDF/XML
version. It might never be used in web browser, and so occupy a
position on the spectrum well away from the presentation end.

In this scenario the RDFa document is simply playing the role of an
equivalent RDF/XML document, with the only difference being that it
can be deployed using HTML infrastructure.

Another scenario would be to have one HTML+RDFa document for humans,
and another for machines, in just the same way that most deployment
scenarios currently involve two different documents (one HTML and one

The main thing is that you now have a choice, and the key point I'm
trying to make is that if the company you were dealing with mixes up
the conceptual and presentation layers, that's nothing to do with
RDFa, since it's perfectly possible to separate them as much or as
little as you like.

In fact it's a little like blaming HTML's @style attribute for causing
you to 'mix up presentation and content', when HTML actually has a
very powerful mechanism for keeping them apart, in CSS stylesheets.



Mark Birbeck, webBackplane

webBackplane is a trading name of Backplane Ltd. (company number
05972288, registered office: 2nd Floor, 69/85 Tabernacle Street,
London, EC2A 4RR)

Received on Monday, 29 June 2009 14:01:41 UTC