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Re: URI: Name or Network Location?

From: Sandro Hawke <sandro@w3.org>
Date: Wed, 21 Jan 2004 06:10:50 -0500
Message-Id: <200401211110.i0LBAofA025064@roke.hawke.org>
To: Patrick Stickler <patrick.stickler@nokia.com>
Cc: "ext Jeremy Carroll" <jjc@hplb.hpl.hp.com>, www-rdf-interest@w3.org, "Thomas B. Passin" <tpassin@comcast.net>


> It may very well be that a URL can be used to denote a 'location'
> (since a URI can denote anything) and that dereferencing it provides
> a representation of that location (which may very well be the thing
> located at that location), but a URL does not inherently (and I
> think rarely does in actual practice) denote an actual web
> "location", per se. I'd argue that from a REST perspective, there is
> no such thing as a "web location". To posit such a thing is to
> violate the essential principle of URI opacity.

(ooops, httpRange-14 filter not properly engaged; rant leaking
out....)

I think "a location" is exactly what an HTTP URI returing "200 OK"
directly identifies.  Indirectly, it can identify what's at that
location, or even more indirectly what you see when you observe that
location, or what you learn about from what you observe at that
location.

location == communications end-point, response point [1], etc.

Such a URI is "a web address".

Strictly speaking, these notions of "location" and "address" are
metaphors, but they are extremely good ones.  A physical mailing
address like "77 Massachusetts Avenue, Cambridge, MA, 02139, USA" is
useful in very much the same way as the web address "http://mit.edu"
is useful.  (Try to imagine if one day a different building were
located at that street address.  Yep, the experience would be a lot
like if a different web site where located at that web address.)

I think any attempt to go against this natural, comfortable, and
common idea (that URIs are web addresses) is doomed to failure, or at
least enormous pain.   Actually, I think the by-fiat imagined name
change from "URL" to "URI" is simarly foolish.

The question is how to finesse identifying people, stars, coffee
makers, etc, into the same address space.  The HashURI approach [2]
involves a sort of second step once you find a location.  "Go to
<address>; then ask for <thing-name>".  The SlashRedirection approach
[3] involves going to a location which turns out to be non-existent
while pointing you at useful information.  "Try to reach <address> and
you'll wind up somewhere else (<address2>) being told about the thing
in question."

    -- sandro

[1] http://esw.w3.org/topic/ResponsePoint
[2] http://esw.w3.org/topic/HashURI
[3] http://esw.w3.org/topic/SlashRedirection
Received on Wednesday, 21 January 2004 06:09:50 GMT

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