RDFa

Just a bit ago, Sandro Hawke announced the launch of the new OWL Working Group (aka OWL 1.1):

W3C is pleased to announce the launch of the OWL Working Group. Ian Horrocks (Oxford University) and Alan Ruttenberg (ScienceCommons) chair the group which is chartered to produce a W3C Recommendation for an extended Web Ontology Language (OWL), adding a small set of extensions and defining profiles identified by users and tool implementers.

I’m looking forward seeing how this evolves …

Kurt Cagle writes about the future of XML, and says a few very interesting things about RDFa:

Similarly, I suspect that while RDFa may have a fairly major hill to climb in terms of adoption, it will likely end up becoming integral to the semantic web fairly soon. Folk ontologies (or folksonomies, as some have referred to them) are not in fact really ontologies at all – they are instead simply property associations. If you can articulate a consisten property relationship using attributes outside of the normal XHTML ones, then you can do more than simply tag a document – you can in fact create relationships between entities in an XHTML document without having to leave the context of that document. That’s what RDFa does. These can then be interpreted by RDF enabled tools, making it possible to achieve something of the holy grail of the semantic web – provide a simple way of nonetheless encoding metadata into a document. I’ve argued for years that RDF as it exists right now is too complex for your average web developer, and what’s more it perforce requires duplication of content between the RDF and XHTML (or whatever document format you’re using). Eliminate this need for duplication by embedded the descriptive relational characteristics directly in the element’s attribute set, and all of a sudden the Semantic Web begins to move away from being unachievable to being doable.

Ivan Herman gave a comprehensive Tutorial on Semantic Web Technologies (incl. some nice slides regarding RDFa). Check it out!

A question came in the mail regarding the fact that the W3C validator currently fails on RDFa. This is true, and it will likely remain true until we finish the RDFa specification for XHTML1. RDFa does involve changing the XHTML schemas, and the plan is under way to do just that.

That said, it’s important to note that, for most RDFa use cases, only the about, property, and content attributes are new. It is currently under debate whether these extra attributes should indeed cause the validator to fail, and all browser implementations we have seen are perfectly happy to accept extra attributes, even in strict, XHTML mode, without any change in rendering.

In other words, prototype away. Validation will work soon. In the meantime, nothing else will break.

We’re starting to put together the web site for RDFa. Bookmark this URL, subscribe to the RSS, we’ll keep you posted. For now, the first thing you should do is check out the RDFa Primer.