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Re: Multiple types from different vocabularies (ACTION-7)

From: Jeni Tennison <jeni@jenitennison.com>
Date: Sun, 30 Oct 2011 10:23:50 +0000
Cc: HTML Data Task Force WG <public-html-data-tf@w3.org>
Message-Id: <012A8CA3-8BBA-4F32-997A-865EF8B77DAA@jenitennison.com>
To: Dan Brickley <danbri@danbri.org>

On 30 Oct 2011, at 09:55, Dan Brickley wrote:
> On 30 October 2011 10:02, Ivan Herman <ivan@w3.org> wrote:
>> The alternative is that microdata->RDF mapping would have an extra rule that makes a mapping of schema.org/type to rdf:type, essentially breaking the uniformity of the mapping.
> I wouldn't support any special case mention of schema.org in the
> official mapping of microdata to RDF. If this is going to be
> special-cased, then special-case it in the syntax rather than
> introduce a dependency on an external project (even if it's a project
> I work on).

Ah. Then we will have to either recommend using rdf:type (which I can't be bothered to write out as I can't remember it) or http://www.w3.org/ns/type. There's not much point us recommending a mechanism for providing multiple types that can't be easily used in the mapping of microdata to RDF. And in that case, please do not define http://schema.org/type as that will just lead to people having to double-up properties in the majority of cases.

This is really down to how schema.org is pitched and the role it wants to play. If it's an external project that might at any moment disappear or be led off in a different direction by a collection of self-interested vendors, then I agree with you. If it's a web-community-based project that is being developed through a light-weight but defined and open process with W3C support and backing then it's much less clear cut; my inclination is to encourage it in that direction.

>> The same for an RDFa mapping for the schema.org vocab. A hack, that is.
>> There is no doubt in my mind that the clean solution would be to allow for a multiple type on the microdata syntax level, just as RDFa does. Anything else is a hack, and an ugly one at that. We may have to go there, but we should be aware of what we are doing...
> Yup. Has anyone talked to Hixie about this lately?

Yes we did, here. [1] He's not going to add support for multiple types from different vocabularies to microdata syntax unless and until they have common use (both being published and consumed). None of the evidence that we are able to provide of that happening at the moment is widespread enough to be persuasive to him.

There are other workarounds to support multiple types, such as just using RDFa, mixing microdata with other syntaxes to supply the extra information, or using hidden sections of the document. We're going to have to present the full range of options, but the extra type property is the easiest to use in simple circumstances.



[1] http://lists.w3.org/Archives/Public/public-html-data-tf/2011Oct/0064.html
Jeni Tennison
Received on Sunday, 30 October 2011 10:24:14 UTC

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