Re: More direct conversion from microdata to RDFa?

Hi Ivan,

On Wed, Oct 12, 2011 at 12:02 PM, Ivan Herman <ivan@w3.org> wrote:

> 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...
>

yes, this proposal comes from the difference in modeling between the 2
syntaxes. I believe that namespaces and types are two different concepts for
RDF folks, but I'm not sure the web developer community really care about
making that distinction, hence the design decision in microdata. I'm not
advocating to remove this distinction from RDFa, but simply to let the
processor deal with it.

Steph.



>
> Sorry:-)
>
> Ivan
>
>
>
>
> 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
>