Long tail of metadata

Ben Adida notes that people are writing about RDFa, which is great, and envisioning conflict with microformats, which is not. As Ben says:

Microformats are useful for expressing a few, common, well-defined vocabularies. RDFa is useful for letting publishers mix and match any vocabularies they choose. Both are useful.

In other words RDFa is a technology.

Evan Prodromou thinks the future is bleak without cooperation. I like his proposed way forward (strikeout added for obvious reasons):

  1. RDFa gets acknowledged and embraced by microformats.org as the future of semantic-data-in-XHTML
  2. The RDFa group makes an effort to encompass existing microformats with a minimum of changes
  3. microformats.org leaders join in on the RDFa authorship process
  4. microformats.org becomes a focus for developing real-world RDFa vocabularies

I see little chance of points one and three occuring. However, I don’t see this as a particularly bad thing. Point three will occur, almost by default: the simplest and most widely deployed microformats (e.g., , and rellicense) are also valid RDFa — the predicate (e.g., tag, nofollow, license) appearing in the default namespace to a RDFa application. More complex microformats may be handled by hGRDDL, which is no big deal as a microformat-aware application needs to parse each microformat it cares about anyway. From an RDF perspective any well-crafted metadata is a plus (and the microformats group do very careful work) as RDF’s killer app is integrating heterogenous data sources.

From a microformats perspecitve RDFa might well be ignored. While transformation of any microformat to RDF is relatively straightforward, transformation of RDF (which is a model, not a format) to microformats is nonsensical (well, I suppose the endpoint of such a transformation could be , though I’m not sure what the point would be). Microformats, probably wisely, is not reinventing RDF (as many do, usually badly).

So why would RDFa be of interest to developers? In a word, laziness. There is no process to follow for developing an RDF vocabulary (ironic), you can freely reuse existing vocabularies and tools, not write your own parsers, and trust that really smart people are figuring out the hard stuff for you (I believe the formal background of the Semantic Web is a long-term win). Or you might just want to, as Ben says “express metadata about other documents (embedded images)” which is trivial for RDF as images have URIs.

Addendum 20060601: The “simplest” microformats mentioned above have a name: elemental microformats.

5 Responses

  1. […] Update 20061204: I didn’t miss Prodromou’s roundup in May, I blogged about it. And forgot. […]

  2. […] considered this headline: If XMP is a microformat, RDFa sure the heck is a […]

  3. […] the most important software project (to a much greater extent on the intranet; and not mentioned, other semantic technologies I’ve blogged about here), ironically now that I’m no longer CTO. Nathan Yergler has […]

  4. […] Semantic web has public and private link information. Microformats standard, but no common model. RDF is new enabling technology to focus on concepts that provides a global guide to webs of data.Information has a context so people can use it.  Purl.org web site example that uses foaf (friend of a friend) with birthday handle. DBpedia data set.  Gleaning Resource Descriptions from Dialects of Languages (GRDDL) W3C recommendation structured content.  RRFa   is RDF attributes (metadata). RDFa is a way to label content to describe a specific type of information, such as a restaurant review, an event, a person, or a product listing. These information types are called entities. Each entity has a number of properties . Freebase , Adaptive Blue. The Curie processing / RDFa spec.  The Open Graph protocol enables any web page to become a rich object in a social graph. Enables any web page to have the same functionality as a Facebook Page. The Web Ontology for eCommerce can be found at Good Relations (see best buy). Semantic Web at InfoQueue . Rdfa split. ODF use of RDFA . Books: Pull: The Power of the Semantic Web to Transform Your Business. CommonTag. RDFa test page. RDFa distiller. rdfa.info web site. RDFa parser for fragments.   Details on Whitehouse. gov site that  uses RDFa .Taxonomy blog. Basics, Long tail […]

  5. […] blogged about this at the time (and forgot and reblogged five months later). I recalled this upon reading a draft HTML Data Guide […]

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