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Re: More direct conversion from microdata to RDFa?

From: Ivan Herman <ivan@w3.org>
Date: Wed, 12 Oct 2011 16:02:30 -0000 (UTC)
Message-ID: <aa69f098a326e42b0b94ab1d5f1a18da.squirrel@webmail.sophia.w3.org>
To: Stéphane Corlosquet <scorlosquet@gmail.com>
Cc: public-rdfa-wg@w3.org
Well... I must admit that I do not like that. It is a very personal thing, but the aspect I see as a problem in
microdata is the fact that the usage of itemtype conflates two very different concepts (at least for me), namely the
choice of a vocabulary and the typing of a concept, in one place. I am pretty uneasy going down that road in RDFa
solely for the purpose of a better translation...



On Wed, October 12, 2011 2:56 pm, Stéphane Corlosquet wrote:
> Converting microdata to RDFa could be made easier by bypassing the vocab
> attribute. Microdata incorporates the concept of vocabulary in the data item
> type via @itemtype. Coming from a microdata perspective, the concept of
> vocabulary URI is an extra element (different from the item type) which
> could be avoided by the following proposal. Since there is a mechanism being
> designed to infer a vocabulary namespace from the microdata @itemtype, RDFa
> could use a similar mechanism, and use the first token of @typeof to
> construct the namespace that we currently put in @vocab.
> Consider the following microdata snippet:
> <div itemscope itemtype="http://schema.org/Person>
>    My name is <span itemprop="name">John Doe</span>.
> </div>
> Currently to convert to RDFa, you need to split @itemtype into two
> attributes: @vocab and @typeof. What I'm suggesting is a direct mapping from
> @itemtype to @typeof without the need of @vocab, where @typeof would include
> the full URI:
> <div typeof="http://schema.org/Person>
>    My name is <span property="name">John Doe</span>.
> </div>
> This would ease the RDFa to microdata and vice versa from a human
> standpoint.
> Note that I'm not suggesting to drop @vocab, but simply to make it optional,
> which would make the common microdata snippets a no brainer to convert to
> RDFa by a simple attributes string replace. In the processing model
> sequence, step 3 would have to include an extra step for the case where
> @vocab is missing, and use the same mechanism as Gregg is defining for
> microdata to RDF conversion. Here is a suggestion:
> [[[
> 3. Next the current element is examined for any change to the default
> vocabulary via @vocab. If @vocab is present and contains a value, its value
> updates the local default vocabulary. If the value is empty, then the local
> default vocabulary must be reset to the Host Language defined default. If
> @vocab is not present but the first token of @typeof is an absolute
> URI, construct the local default vocabulary by removing everything following
> the last SOLIDUS U+002F ("/") or NUMBER SIGN U+0023 ("#") in the first token
> of @typeof.
> ]]]
> Thoughts?
> Steph.

Ivan Herman, W3C Semantic Web Activity Lead
URL: http://www.w3.org/People/Ivan/
FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Wednesday, 12 October 2011 16:02:59 UTC

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