* Aryeh Gregor Simetrical+wikilist@gmail.com [Thu, 21 Jan 2010 18:55:38 -0500]:
Okay, I'll grant that for an RDF-style use-case, parser functions are a better bet than the alternatives. However, I'm not sure that's the case for inline markup, in the limited cases where we want that (e.g., image licenses). The problem here is that you'd have to associate the metadata with particular phrases. You can't say {{#prop:license|CC-BY-SA-2.0}} and output that as proper microdata/RDFa -- or rather you could, but only by creating empty content nodes someplace. I guess that would work . . . it's not good practice if you're hand-authoring, and it would take a bit more space, but it might indeed make sense from our POV.
To output the magic word / parser function as a properly defined metadata, one has to define the type of "license" (associate with "vocabulary" which has proper xmlns) in the source of definition page in NS_PROPERTY namespace, which has address [[Property:license]]. On the Property:License page there will be a mapping of "CC-BY-SA-2.0" string to "expanded xmlized value".
But then there's the question of writing it. The code for raw microdata/RDFa output is already written, and is pretty trivial besides. Is anyone willing to write core code to do this metadata abstraction with a parser function, and output in appropriate formats? If not, the choice is microdata, RDFa, or nothing.
Experts in Parser probably can do that fast enough, however him / they might be busy with more important jobs.
Not for search engines. They're spidering all the pages anyway, so it's easier for them to not retrieve a separate page. Besides, how would they know how to find the metadata if it's not included or pointed to on the page in some standard format?
Duesentrieb pointed out that MediaWiki built-in search can benefit from that, as well. Both metadata generation for the external engines and internal storage (similar to SMW) could be implemented. However, it's much simplier to perform metadata generation without the storage backend (less optimization, scalability issues, code review). This way the goal can be achieved in incremental steps. SMW can be adapted to use such syntax, then it can be used to retrieve the data from Wikipedia dumps, by installing the SMW at external, less-trusted server (toolserver?), where the code review is not so critically important. Dmitriy