So, congrats to Leo and Richard: Cool URIs for the Semantic Web is a W3C Working Draft, now. They basically discuss URI design issue regarding both humans and machines. Why do we care? Well, let’s have a look into the document:
The solutions described in the following apply to deployment scenarios in which the RDF data and the HTML data is served separately, such as a standalone RDF/XML document along with an HTML document. The metadata can also be embedded in HTML, using technologies such as RDFa [...], microformats and other documents to which the GRDDL [...] mechanisms can be applied. In those cases the RDF data is extracted from the returned HTML document.
What is your opinion? Do you have practical experiences — that is: no toy setup 
— in designing URIs in an XHTML+RDFa environment?
Fabien Gandon has produced a great set of introductory RDFa slides. Here they are.
David Decraene is looking for feedback on his article Embedding OWL-RDFS syntax in XHTML with RDFa, which is a “Short introduction to RDFa, OWL and Microformats”, and aims to come up with:
a solution that reconciles the ease of use of Microformats with the expressivity of a language like OWL. Some problems hindering OWL adoptation will be highlighted, and a first experiment with the use of RDFa mark-up to embed OWL data directly into an XHTML page will be demonstrated, a solution that can be considered as a step higher than Microformats on the evolutionary ladder of the web.
He argues that OWL has a poor presence on the web, attributing this mainly to the fact that no-one has explored approaches to “align / integrate OWL with current web content”:
For ontological data to truly be useful, you need to somehow tie current web content with semantic classes and instances. OWL has failed miserably in this respect so far. It is much like a far away island of Eden, and a man without a canoe. All the important data could be there but no-one knows how to reach it. Granted, OWL does define a standard format for data interchange between applications, but this limited scope cannot be what the semantic vision is about.
Interestingly enough, if you replaced the word ‘OWL’ with the word ‘RDF’, you’d have pretty much the main motivations that spurred the development of RDFa in the first place. David goes on to give an example:
What we need is semantic annotation. You need to be able to tag sections of your content with explicit ontology classes and even relations, without it hindering the display of your content. If you wrote a piece on a certain bordeaux for example, you could mark up the section as being about an instance of wine, perhaps even with some properties defined (or even more amazing, just by knowing it is about wine properties can be extracted automatically, a mention of red is bound to be about the wine color).
Whilst there is no doubt that the kind of complex RDFa David uses in his post is not for the everyday user of RDFa, the fact that RDFa can be used for these kinds of complex examples shows that the architecture is solid.
(This rdfa.info post also appears on XForms and Internet Applications.)
