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Re: Mapping Microdata to RDF

From: Gregg Kellogg <gregg@kellogg-assoc.com>
Date: Wed, 26 Oct 2011 08:27:43 -0400
To: Toby Inkster <tai@g5n.co.uk>
CC: "public-html-data-tf@w3.org" <public-html-data-tf@w3.org>
Message-ID: <B144B961-6B73-43D9-AEAF-706F35577C2F@kellogg-assoc.com>
On Oct 26, 2011, at 4:52 AM, "Toby Inkster" <tai@g5n.co.uk> wrote:

> A few comments on
> <https://dvcs.w3.org/hg/htmldata/raw-file/24af1cde0da1/microdata-rdf/index.html>...
> 1. Creating RDF collections for repeated properties is an awful idea.
> Consider the example in appendix A. The object of the frbr:realization
> is a blank node of type rdf:List. According to the FRBR Core vocab, the
> range of frbr:realization is frbr:Expression. If we assume that
> frbr:Expression and rdf:List are disjoint classes (which seems to be a
> reasonable assumption), you've created a logical contradiction. So the
> graph generated by parsing the microdata does not match up to the
> expectations of the vocabulary, and probably does not match up to the
> expectations of the page author.

I'm not a big fan either, and others have noted the rdfs:range issue. It may be that we need another registry value for this; one for property URL generation, and another for value order preservation. It's a shame we can't actually use rdfs:range information when processing.

> I can understand the desire to preserve document order to cover
> certain use cases, but it's possible to do that outside of the RDF
> model. (e.g. Rather than parse the page as a whole and operate on the
> graph returned, you could supply a callback function to the parser to
> be called as each triple is extracted from the page. The callback
> function would then receive triples in document order.)

Microdata already specifies an API for returning this info in order.

> TLDR: generating collections breaks ranges.
> 2. Are there use cases where your new behaviour for <blockquote> and
> <q> is actually useful? Seems to me that most people would expect
> <blockquote itemprop> and <q itemprop> to use the contents of the
> element as the property value, irrespective of whether @cite is present.

This is going to be dropped in the next draft, as there has been no support expressed for it.

> Hmmm... only two comments? That must mean you did a good job.

Thanks, Toby!


> -- 
> Toby A Inkster
> <mailto:mail@tobyinkster.co.uk>
> <http://tobyinkster.co.uk>
Received on Wednesday, 26 October 2011 12:28:29 UTC

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