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Re: Meaning of property "url"

From: Dan Brickley <danbri@danbri.org>
Date: Tue, 23 Oct 2012 08:25:51 -0700
Message-ID: <CAFfrAFo5dSpauGxLVg17O7GTHb02gwHuLmnTL-uHz=1+Mv7EnQ@mail.gmail.com>
To: Michael Hopwood <michael@editeur.org>
Cc: Ed Summers <ehs@pobox.com>, Cord Wiljes <cwiljes@cit-ec.uni-bielefeld.de>, "public-vocabs@w3.org" <public-vocabs@w3.org>
A few observations -

* We want all Things to be identifiable using URI/IRI/URL identifier notations

* In the HTML5 the specs use 'URL" rather than "URI"; at launch
Schema.org's primary notation was HTML5 MIcrodata, so we inherit that
usage. But Schema.org also targets mainstream developers and
publishers who often are not so familiar with 'URI' or 'IRI', but feel
they know what an 'URL' is

See http://developers.whatwg.org/introduction.html#willful-violation
http://developers.whatwg.org/urls.html

HTML5's usage of 'URL' is explicitly in terms of URI and IRI and the
notion of a 'resource'

* In RDF, we use 'resource' as a synonym for Thing (ie. all things can
be considered resources), rather than something like
'http-accessible-information-object', which seems to be some people's
reading of the term. I think Schema.org is closer to the 'thing'
reading.

* Microdata has an 'itemid' attribute, for Thing identifiers
(analagous to resource= in RDFa Lite), see
http://www.w3.org/TR/rdfa-lite/#resource for the RDFa version.

* The use of schema.org/url is broadly equivalent to using itemid or
resource attributes from Microdata and RDFa; it takes the items Web
identifier and expresses it explicitly as a property value.

* There is plenty of room still for interpretation, best practice,
clearer guidelines; the "How do we identify real world entities"
debate is as old as the Web.

* Schema.org's deployment in mainstream Web content places some
practical constraints for some publishers; for example, a Movie site
where a page /person_321/ links to /tvshow-67241/ might have an
itemprop="actor" (microdata) or property="actor" (rdfa) annotation.
That's nice and simple, but parsing gives the actor TV show the same
URI/IRI/URL as the page describing them; i.e. the http-range-14.  A
more complex site design (markup and identiifers) that gives different
IDs to pages and entities is of course possible, but it's not clear
we'd see strong adoption easily.

 So I'd not read too much into 'url'. It's somewhere you can put a Web
identifier for the thing being described. As conventions for this in
the Web standards community mature, we should be able to be more
precise on this.

Dan

p.s. http://www.w3.org/wiki/WebSchemas/sameThingAs is somewhat related
Received on Tuesday, 23 October 2012 15:26:25 GMT

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