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RE: Meaning of property "url"

From: Young,Jeff (OR) <jyoung@oclc.org>
Date: Tue, 23 Oct 2012 22:43:52 -0400
Message-ID: <52E301F960B30049ADEFBCCF1CCAEF5911D98F09@OAEXCH4SERVER.oa.oclc.org>
To: "Dan Brickley" <danbri@danbri.org>, "Michael Hopwood" <michael@editeur.org>
Cc: "Ed Summers" <ehs@pobox.com>, "Cord Wiljes" <cwiljes@cit-ec.uni-bielefeld.de>, <public-vocabs@w3.org>
In the WorldCat.org Linked Data, the intention is to use schema:url to associate a Linked Data identifier/description of something that is located "elsewhere" on the Web. So, for example, Roy Fielding's thesis is "located on the Web" (in the original "URL" sense) here:

http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm


Nevertheless, this "information resource" (to risk the wrath of httpRange-14 haters) can be identified and described elsewhere (in the Linked Data "URI" sense) by "dedicated observers of reality". For example:

http://www.worldcat.org/oclc/{oclcnum}


One of the assertions returned from the latter would then be:

<http://www.worldcat.org/oclc/{oclcnum}>
	a library:Thesis;
	schema:url <http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm> .

(It's a little annoying that I can find a WorldCat record for the print manifestation/item of one of my favorite "creative works", but not a record for the Web manifestation/item. That's why I've cheated in this example with {oclcnum} as an abstract variable rather than citing a specific oclcnum value. I'm sure examples are plenty of honest examples other than Fielding's thesis in the WorldCat.org dataset, but not after 10pm and not before an extended 5 day weekend. :-)

Jeff

> -----Original Message-----
> From: Dan Brickley [mailto:danbri@danbri.org]
> Sent: Tuesday, October 23, 2012 11:26 AM
> To: Michael Hopwood
> Cc: Ed Summers; Cord Wiljes; public-vocabs@w3.org
> Subject: Re: Meaning of property "url"
> 
> 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 Wednesday, 24 October 2012 02:44:17 GMT

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