RDFa and microformats

During the course of writing an email recently, I needed to compare microformats with RDFa. I thought the list might be of interest to others.

Microformats

• Microformats gets into real trouble when you try to combine more than one 'format' (in fact, rules of combination have to be defined);


• it requires converting already existing langauges so that they work within the microformat rules--painful and slow, given that languages such as FoaF have already had an enormous amount of work put into them, and this must be almost completely repeated;


• there is no notion of namespacing;


• adding new languages seems to be based on a few key individuals;


• there is no way to validate;


• it isn't actually a "poor man's semantic web", as some suggest, since it isn't providing a generic mechanism. Instead it provides a way to hand-craft a small number of use-cases, which in turn means that some other process still has to do the work of working out what it means. For each format another 'process' will be required.

RDFa

• RDFa tackles all of these issues by providing a series of general rules that can be applied to any metadata, rather than specific rules for specific formats;


• be written as simply as microformats;


• scale to any level of complexity;


• allow QNames to be used if required, to provide full namespacing;


• make use of any RDF taxonomy;


• operate at the level of document structure semantics, as well as the document content semantics.