W3C home > Mailing lists > Public > www-tag@w3.org > July 2011

Re: Dropping RDF mapping from microdata spec

From: Tim Berners-Lee <timbl@w3.org>
Date: Thu, 28 Jul 2011 13:19:15 -0400
Cc: Michael Hausenblas <michael.hausenblas@deri.org>, Richard Cyganiak <richard.cyganiak@deri.org>, "www-tag@w3.org List" <www-tag@w3.org>
Message-Id: <B11C3E22-9B15-4372-A427-2BE55D97FD11@w3.org>
To: Jeni Tennison <jeni@jenitennison.com>

On 2011-07 -27, at 17:25, Jeni Tennison wrote:
> [...]
> From what I can see, the documented meaning of http://schema.org/startDate and http://schema.org/endDate is different depending on whether the item is a TVSeason/TVSeries or an Event. IIRC, one reason that Hixie gives for the complexity of the generated property URIs in the current microdata/RDF mapping is to ensure that properties with potentially different semantics (that appear on items of different types) have distinct URIs. But of course when you have inheritance in a vocabulary like schema.org, you don't want distinct URIs by type.
> Makes me think you can't have a generic mapping that gives a good output in RDF terms.

Yes. It is important that the semantics of the property is the same, as this gives much greater power of data re-use.

I think the spec can't just specify the syntax, it has to specify the RDF
mapping. It is only well-defined when it has defined the 
mapping from the HTML DOM into abstract RDF triples.
People don't have to use the DOM or the RDF model in their code
but as those are the abstractions which we have written a lot of
code in terms of, that is the reference point for the spec to 
produce interoperability.

It can't be a mapping which maps to a notional URI which is hopeless
in practice.  It has to map to a URI which looks just like the normal sort of URIs
which RDF systems use, supported on the web as linked data, like FOAF, etc.


> Cheers,
> Jeni
> -- 
> Jeni Tennison
> http://www.jenitennison.com

Received on Thursday, 28 July 2011 17:19:23 UTC

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