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Re: Fwd: TAG issues during technical plenary

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Wed, 23 Jan 2002 10:45:25 +0000
Message-Id: <>
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: Brian McBride <bwm@hplb.hpl.hp.com>, w3c-rdfcore-wg@w3.org
At 06:04 PM 1/22/02 -0600, Pat Hayes wrote:
>Another is that a URI implicitly identifies a process which when set in 
>motion will result in some value (which might itself be a name or 
>referring expression in the first sense, or a document or structure in the 
>second sense) being 'delivered' to the 'caller', ie as a kind of 
>computational identifier whose value reflects the current 'state' of the 
>Web itself. (This latter would be one way to make sense of the 
>above-mentioned discussion of 'mapping' versus 'content' in RFC2396, for 

FWIW, this seems closest to the mental model that works best for me ... 
roughly, a URI denotes a function that, when applied to some arguments, 
returns some data entity.  In, say, an HTTP GET operation, some of the 
arguments are implicit (the fact that it's a GET operation, the state of 
the "resource" when the function is evaluated) and some are explicit (HTTP 
request parameters, request body, etc.).

>A more recent document (http://www.w3.org/TR/uri-clarification/) 
>unfortunately only adds to the confusion. It notes that a 'classical' view 
>partitioned URIs into names (URNs) versus location identifiers (URLs), but 
>goes on to describe a 'contemporary' view which fails to classify them in 
>any meaningful way. This does not add any clarity to the overall 
>framework, however. This document for example states that according to the 
>contemporary view,  "a URL is a type of URI that identifies a resource via 
>a representation of its primary access mechanism (e.g., its network 
>"location"), rather than by some other attributes it may have." This seems 
>to imply that the resource *is* the document that is retrieved by using 
>the URL (since that is the entity that can be said to have a network 
>"location"), rather than anything that such a document may indicate or 
>name, such as a book in a library (cf. RFC2396).  It also assumes that 
>location is an attribute, which raises a number of other questions, 
>including whether or not the same entity (resource) might have different 
>locations at different times (by changing this attribute).

In a sense, I think this is right, in that any attempt to classify URIs 
raises more questions than it answers.  But I also think this is a separate 
issue from the question "What is a 'resource'?" that you posed, and (if 
only for political/social reasons) the classification of URIs debate should 
be kept separate from consideration of your question.


Graham Klyne                    MIMEsweeper Group
Strategic Research              <http://www.mimesweeper.com>
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Received on Wednesday, 23 January 2002 06:27:36 UTC

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