[whatwg] Microdata and Linked Data

Eduard Pascual herenvardo at gmail.com
Fri Jul 24 04:29:54 PDT 2009

On Fri, Jul 24, 2009 at 1:07 PM, Peter Mika<pmika at yahoo-inc.com> wrote:
> [...]
> #2
> The other area that could be possibly improved is the connection of type
> identifiers with ontologies on the web. I would actually like the notion of
>  reverse domain names if
> -- there would be an explicit agreement that they are of the form
> xxx.yyy.zzz.classname
> -- there would be a registry for mappings from xxx.yyy.zzz to URIs.
> For example, org.foaf-project.Person could be linked to
> http://xmlns.com/foaf/0.1/Person by having the mapping from org.foaf-project
> to http://xmlns.com/foaf/0.1/.
> It wouldn't be perfect, the FOAF ontology as you see is not at
> org.foaf-project but at com.xmlns. However, it would be a step in the right
> direction.
> [...]
> #4
> I don't expect that writing full URIs for property names will be appealing
> to users, but of course I'm not a big fan either of defining prefixes
> individually as done in RDFa with the CURIE mechanism. Still, prefixes would
> be useful, e.g. foaf:Person is much shorter to write than
> com.foaf-project.Person and also easier to remember. So would there be a way
> to reintroduce the notion of prefixes, with possibly pointing to a registry
> that defines the mapping from prefixes to namespaces?
> <section id="hedral" namespaces="http://www.w3c.org/registry/"
> item="animal:cat">
> <h1 itemprop="animal:name">Hedral</h1>
> </section>
> Here the registry would define a number of prefixes. However, the mechanism
> would be open in that other organizations or even individuals could maintain
> registries.

IMO, both of these proposals are quite related. However, you added
substantial differences I can't really understand between them.

For #2 you suggest to have a sort of centralized registry of mappings
between the reversed domains and the vocabularies they refer to. What
happens if next year I have to use an unusual vocabulary for my site
that is not included on the registry? Would I have to get the
vocabulary included on the registry before my pages' microdata can be
mapped to the appropriate RDF graph?
On the other hand, on #4, you are opening the gate to independent
entities (be them organizations or individuals) to define the prefixes
they would be using for their pages' metadata: why don't apply this to
#2 as well? IMO, it would be more important for #2 than for #4; since
#4 only provides syntax sugar while #2 enables something that would be
undoable without it (mapping Microdata to arbitrary RDF).

About #1, I'm not sure about what you are exacly proposing, so I can't
provide much feedback on it. Maybe you could make it a bit clearer:
are you proposing any specific change to the spec? If so, what would
be the change? If now, what are you proposing then?
Finally, about #3 I'm not familiar with the OWL vocabulary, so I can't
say too much about it. But if your second proposal gets into the spec,
then this would become just syntax sugar, since any property from any
existing RDF vocabulary could be expressed; and if #4 also got in, the
benefit of "built-in" properties would be minimal compared to using a
reasonably short prefix (such as "owl:").

Just my two cents.

Eduard Pascual

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