- From: Ian Hickson <ian@hixie.ch>
- Date: Mon, 3 Aug 2009 10:10:00 +0000 (UTC)
(I trimmed public-html from the CC list to avoid cross-posting, and because the whatwg list has had most of the traffic on this topic so far; please feel free to forward this to public-html if you would rather discuss that there instead.) On Fri, 24 Jul 2009, Peter Mika wrote: > > The use of a URI as the value of the id attribute. It seems to me there > is actually nothing in the spec that would stop this: > > "Identifiers are opaque strings. Particular meanings should not be derived > from the value of the id attribute." > > This is great because in principle I could do something like: > > <section id="http://john.example.com#hedral" item="org.example.animal.cat > com.example.feline"> > <h1 itemprop="org.example.name com.example.fn">Hedral</h1> > </section> > > I assume you can achieve something similar with the "about" property but that > would require me to write: > > <section item="org.example.animal.cat com.example.feline"> > <h1 itemprop="org.example.name com.example.fn">Hedral</h1> > <a itemprop="about" href="http://john.example.com#hedral"/> > </section> > > This is longer by itself, and if I want an internal identifier as well, than I > have to write: > > <section id="hedral" item="org.example.animal.cat com.example.feline"> > <h1 itemprop="org.example.name com.example.fn">Hedral</h1> > <a itemprop="about" href="http://john.example.com#hedral"/> > </section> In practice, all the use cases that were brought up that needed to identify the item were cases where there was a URL already in the page, e.g. in a link or an <img> or a <video> element, such that it actually ends up better if we use itemprop=about rather than having a dedicated attribute (like id="" or about="") for identifying types. Are there use cases where this is not the case? For example, when would you need to have an internal identifier? > 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. What problem is this solving? > I would consider adding the sameAs property as part of the standard > vocabulary. This is a term from the OWL vocabulary that is widely used > in the Linked Data world for connecting entities that are deemed to be > equivalent. Alternatively, we could add the entire RDFS and OWL > vocabulary to the spec. Could you elaborate on this? What are the use cases that this is intended to address? What do you mean by "adding the sameAs property"? > 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. I'm definitely against any in-page indirection mechanism, because we have seen with XML Namespaces (and with RDFa) that prefixes are simply a huge source of problems. However, there actually already is a registry for registering strings that start with a keyword and a colon: the scheme registry. So if animals become important enough that they need their own scheme, I guess people could register them that way. Alternatively, a short domain followed by a keyword seems like a reasonable option: instead of "animal:cat", have "org.animal.cat": it's only four more characters. (Actually, with ICANN considering opening up TLDs, people could just register those: "animal.cat" is a valid reverse DNS label if "animal" is a TLD!) -- Ian Hickson U+1047E )\._.,--....,'``. fL http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,. Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
Received on Monday, 3 August 2009 03:10:00 UTC