rdf:about, rdf:ID and anonymous resources from Pierre-Antoine CHAMPIN on 2000-10-04 (www-rdf-interest@w3.org from October 2000) (original) (raw)

From : "McBride, Brian" <bwm@hplb.hpl.hp.com>

What I was trying to say to Tim was there was nothing to stop him doing what he suggested, but that he might also consider the alternative of adding the fragment id's automatically.

Once we are on the subject, I still have some problem with that ID thing.

What exactly is the point of writing, in a file foo.rdf <rdf:Description ID="bar"> As I understand it, it "defines" the resource foo.rdf#rdf So, why not simply write <rdf:Description about="#bar"> Again, as I understand it, this is because the fragment id "bar" does not exist in the file foo.rdf, so rdf:ID allows to define AND describe it.

Well, the fragment id "bar" does not exist in foo.rdf. So what ? Most of the time, rdf:ID is used (as far as I know) for classes or properties: resources that are abstract by essence, that can not be retrieved anyway ! Naming them foo.rdf#bar or whatever is nothing but a convention.

Defining a fragment id allows the URI of the resource to return the description of the resource ; but the description is a PROPERTY of the resource, not the resource itself. The metaporperty rdfs:isDefinedBy is intended for that, and XPointer allows to point to any rdf;Description tag in a more standard way.

T(rdfs:isDefinedBy, my_resource, foo.rdf#xpointer(...))

So, did I miss something about rdf:ID ?

Pierre-Antoine

Bo�te aux lettres - Caramail - http://www.caramail.com