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Re: Do resources have representations?

From: Norman Walsh <Norman.Walsh@Sun.COM>
Date: Mon, 28 Jul 2003 12:11:31 -0400
To: www-rdf-interest@w3.org
Message-ID: <87n0eyfx70.fsf@nwalsh.com>

Hash: SHA1

/ Benja Fallenstein <b.fallenstein@gmx.de> was heard to say:
| However, if I pointed my browser to <http://example.org/1434>, I would
| not consider it correct behavior if my browser opened a HTTP
| connection to <http://example.net/~foo/bar> and showed me the content
| that the web server at that address returns -- even if I have proof
| that these two URIs denote one and the same resource!

Uhm, even if the representation returned by <http://example.org/1434>
included a Location: header that redirected your browser? That might
be one reasonable way of instantiating "is the same as" if you are the
authority with control over example.org and you believe the assertion
that it is the same as <http://example.net/~foo/bar>.

|> I do observe, however, that the assertion that
|> <http://example.org/1434> and <http://example.net/~foo/bar> identify
|> the
|> same resource is not one that I would accept without proof.
| I assumed that you had proof.
| Assume that at <http://example.org/1434>, you find a web page that says,
|      The URI of this page (http://example.org/1434) denotes Norman Walsh
|      (Norman.Walsh@Sun.COM).
| At <http://example.net/~foo/bar>, you find a page that says,
|      The URI http://example.net/~foo/bar has been assigned to denote
|      Norman Walsh, the person with email address Norman.Walsh@Sun.COM.
| Would this be good enough? Of course, we could also assume that you
| have written, notarized documents from the domain name owners.

I don't know how to solve the "web of trust" problem. All those
representations do is push the problem up a level: now I believe the
assertions if I trust the folks that made each of them.

|> In short: it appears that you want to associate a URI with a particular,
|> closed set of representations *independent of* the act of retrieving them.
| I don't care about the set being single or closed. I do want to be
| able to say, URI X has representation Y; so e.g. my web server can
| serve Y when a representation of X is requested.

In a context where it was appropriate for your system to serve as a
proxy for the web server running at X's domain, that sounds fine to

|> You can't. Representations are ephemeral, they change without warning and
|> without changing the resource that the URI identifies.
| Well. If I have retrieved a representation, I cannot conclude that it
| is the only representation available at that URI, nor can I conclude
| that another representation will not be available at that URI in the
| future. I can, though, conclude that it is *one* representation
| available at that URI at the time I retrieved the resource.


| This also doesn't mean that it is impossible to state that a
| particular URI maps to a particular representation, nor does it mean
| that it isn't useful to make such a statement. For example, when you
| configure your web browser.

Also true.

                                        Be seeing you,

- -- 
Norman.Walsh@Sun.COM    | Art happens--no hovel is safe from it, no
XML Standards Architect | prince may depend upon it, and vastest
Web Tech. and Standards | intelligence cannot bring it about.--J. M.
Sun Microsystems, Inc.  | Whistler
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Received on Monday, 28 July 2003 12:11:54 UTC

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