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Re: [httpRange-14] What do HTTP URIs Identify?

From: Tim Bray <tbray@textuality.com>
Date: Tue, 06 Aug 2002 10:51:29 -0700
Message-ID: <3D500CA1.1000909@textuality.com>
To: www-tag@w3.org

Tim Berners-Lee wrote:

> Similarly, in RDF, when http://example.com/foo#bar identifies something
> and there are some facts in the document http://example.com/foo about
> #bar, then those facts can be deemed definitive because of the
> social structure which gives the owner of the identifier a mechanism, 
> through
> ownership of the domain and control of the server for that domain, the 
> ability
> to control every representation of that document. Hence, any statement
> on the web which is inconsistent with that document is simply wrong -
> or the system has broken somewhere.

Once you step outside of the domain of infrastructure facts ("was 
authored by", "was last changed on", "is available in PDF") I think the 
assertion that ownership == correctness falls apart.  Once you get into 
the domain of interesting semantics that impact the real world, I will 
tend to flat disbelief of any assertions that come from the web sites of 
political parties, consulting accountants, and fundamentalist religions, 
*especially* when they are making claims about resources in their own 
space.  In fact I may have issues with claims as basic as "authored by" 
& "last changed date" when made by religions about their own scriptures.

> The idea that is "inevitable" that people will use the same URI to 
> identify different things
> is true only in that is "inevitable" that people will plus 110V 
> appliances into 220V circuits. That is, they can't do it without 
> breaking the protocols. 

I just disagree.  If I want to assert that the W3C isA vendor consortium 
and hasOfficesIn in Cambridge, Sophia-Antipolis, and Keio, and I do this 
using http://www.w3.org to represent the W3C, this will tend to just 
sort of work.  It will work better if we all agree, for any given 
organization, what URI to use when talking about it, but that's an 
organizational not a technical problem, and in many domains such 
agreement is simply not achievable.

> Any suggestion that it is "OK" to 
> just use the same URI to denote two different things, or to suggest one 
> has the right in a hostile way to claim to define a URI in someone 
> else's space, is to break the rules.

I also don't think that code 404's are OK, but they happen and the 
architecture has to be able to handle it; if the SemWeb can't work in 
the presence of contradictory assertions, it can't deal with the real 
world and I'm not interested in it.  The metaphor is compelling: 
hypertext systems that can't work in the presence of 404's can't deal 
with the real world and I'm not interested in them.

As for people landgrabbing URIs in someone else's space, shouldn't this 
be self-defeating (especially when someone tries to dereference them)? 
I can see us issuing a finding that this is a Bad Thing to Do, if you 
think it would help.

> "Er... and how do you disallow identifiers from identifying whatever 
> people think they identify?", you ask.
> 
> By specifications, darn it!

Can you provide some draft specification language that would live in the 
architecture doc that would achieve this objective?  [You probably 
already have, but this thread has gone on too long.]  -Tim
Received on Tuesday, 6 August 2002 13:51:32 GMT

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