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

From: Dan Brickley <danbri@danbri.org>
Date: Sun, 30 Oct 2011 11:55:51 +0100
Message-ID: <CAFNgM+baLF5rCv+Sb9tMSfUtiNkBeT+WDOK=3JE92TRHfhOYAQ@mail.gmail.com>
To: Jeni Tennison <jeni@jenitennison.com>
Cc: HTML Data Task Force WG <public-html-data-tf@w3.org>
On 30 October 2011 11:23, Jeni Tennison <jeni@jenitennison.com> wrote:
> Dan,
> On 30 Oct 2011, at 09:55, Dan Brickley wrote:
>> On 30 October 2011 10:02, Ivan Herman <ivan@w3.org> wrote:
> [snip]
>>> 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.

Ah ok, we didn't communicate as clearly as I'd thought earlier then :)

When I said "...or is the main purpose to have shorter URIs syntactically?  Both
because the 1999 URI is long, and because Microdata  makes certain
things easier (shorter) if a property is in the same namespace as the
currently-focal type." ... I meant something like
"... so for authors of Microdata markup that uses Schema.org, it'll be easier".

Rather than "for all users of Microdata regardless of the main
schema(s) they're interested in".

IMHO it's fine to say "If you want to mention another type, we expect
the property <http://schema.org/type> to be available long term, and
always to be defined as meaning the same thing as RDF's rdf:type
property". What concerned me was the hint/suggestion that a mapping
might reference that property more deeply, as an integral part of
Microdata-as-RDF syntax.

I think it reasonable to get a declaration from Schema.org that this
particular property will always mean 'rdf:type', and I hope to see the
project make arrangements for long-term maintainance / preservation,
perhaps along the lines I explored with Tom Baker for the FOAF/DCMI
agreement <http://dublincore.org/documents/dcmi-foaf/>. However it is
early days yet and Schema.org is currently more focussed on the
present than on its distant future.

> 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.

It has elements of the former, but leans towards the latter. However,
it isn't a democracy, so a lot depends on what people mean by 'open
process' here. I've tried to outline a process for how the Schema.org
project and the Web Schemas TF are related here:
http://www.w3.org/wiki/SchemaDotOrgProcess ... maybe you could have  a
glance and see how that style fits with the needs here.

>> 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.

Thanks. Does that conversation have an URL?

> 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.

Great. I'll investigate whether I can find some use cases for


Received on Sunday, 30 October 2011 10:56:21 UTC

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