Re: More direct conversion from microdata to RDFa?

Ivan,

On Fri, Oct 14, 2011 at 8:05 AM, Ivan Herman <ivan@w3.org> wrote:

> My apologies. I just saw that the WG discussed it yesterday. I should have
> read the minutes before answering this...
>

No need to apologize. Thanks Ivan for adding to the conversation, you
brought additional arguments which were not mentioned during the call. I
agree with you and the rest of the group that this proposal is probably not
a good idea, so I'll drop it now :)

Steph.


>
> Ivan
>
> On Oct 14, 2011, at 10:00 , Ivan Herman wrote:
>
> >
> > On Oct 13, 2011, at 17:58 , Stéphane Corlosquet wrote:
> >
> >> 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.
> >
> > This is a hypothetical reason. I am not sure our goal is to mimic all
> aspects of microdata without further proofs.
> >
> >> I'm not advocating to remove this distinction from RDFa, but simply to
> let the processor deal with it.
> >
> > But having them both does muddle the waters, at least in my view. There
> are a number of corner cases (some of them are actually discussed in
> conjunction with the microdata->RDF mapping, too) which we may have to deal
> with:
> >
> > - If there are several items in @typeof, which one determines the
> vocabulary? The first one? Doesn't that create issues for authors as a
> possible source of errors (in my view it does)
> > - @typeof values may not be full URI-s (in contrast to microdata). Ie, a
> @vocab expansion is also valid for @typeof; what are exactly the rules
> there?
> > - What happens if there is a @typeof but there is also a valid @vocab
> statement somewhere 'up' in the tree?
> > - What are the exact rules of deducing a vocab URI from a type value?
> >
> > All these issues can be answered one-by-one, of course, and none of these
> demand rocket science. But they do make things way more complicated.
> >
> > As you said in your earlier response to Toby, @typeof is already
> overloaded insofar as it also creates a new subject in some cases. That is
> true and, to be honest, this is one of the aspects of RDF1.0 that I really
> do not like at all. I would prefer to remove any overloaded features from
> @typeof (although, alas!, that ship has already sailed) rather than adding
> to it.
> >
> > To make it clear: if the majority of the WG decides for this feature, I
> will not lie down the road. But you still have to roll over me:-)
> >
> > As I said before: sorry, Stéphane, this time we disagree...:-)
> >
> > Ivan
> >
> >
> >>
> >> 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
> >>
> >
> >
> > ----
> > Ivan Herman, W3C Semantic Web Activity Lead
> > Home: http://www.w3.org/People/Ivan/
> > mobile: +31-641044153
> > PGP Key: http://www.ivan-herman.net/pgpkey.html
> > FOAF: http://www.ivan-herman.net/foaf.rdf
> >
> >
> >
> >
> >
>
>
> ----
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> PGP Key: http://www.ivan-herman.net/pgpkey.html
> FOAF: http://www.ivan-herman.net/foaf.rdf
>
>
>
>
>
>