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Re: Dropping RDF mapping from microdata spec

From: Jeni Tennison <jeni@jenitennison.com>
Date: Fri, 29 Jul 2011 19:47:52 +0100
Cc: Michael Hausenblas <michael.hausenblas@deri.org>, Richard Cyganiak <richard.cyganiak@deri.org>, "www-tag@w3.org List" <www-tag@w3.org>
Message-Id: <923A1BB0-D969-405B-AAAA-DBB40C80B1B3@jenitennison.com>
To: Tim Berners-Lee <timbl@w3.org>
Tim,

On 28 Jul 2011, at 18:19, Tim Berners-Lee wrote:
> On 2011-07 -27, at 17:25, Jeni Tennison wrote:
>> 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.

I agree that it's important to have a mapping. I don't see that it needs to be done within the microdata spec to be useful. I think it's something that can be layered on top of microdata in the same way that GRDDL was layered on top of XHTML.

> 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.

I agree. The current microdata/RDF mapping penalises people who want to reuse vocabularies that have been developed for RDF because they can't use simple short-name properties but have to use URIs for properties.

Jeni
-- 
Jeni Tennison
http://www.jenitennison.com
Received on Friday, 29 July 2011 18:48:30 GMT

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