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Re: Valid representations, canonical representations, and what the SW needs from the Web...

From: Paul Prescod <paul@prescod.net>
Date: Mon, 03 Feb 2003 11:07:59 -0800
Message-ID: <3E3EBE0F.2070409@prescod.net>
To: Sandro Hawke <sandro@w3.org>
CC: Patrick.Stickler@nokia.com, www-tag@w3.org

Sandro Hawke wrote:
>
>>From [2]: How does REST handle the case of there being
> two different web pages about the same thing?  

So there are two different web pages about the same thing. Does that 
make the web pages _themselves_ the same resource? According to that 
logic, a NYT article and a WSJ article are the same article if they talk 
about the same event.

To me, this misunderstanding gets at an important aspect of the debate. 
People are always talking about using web pages to represent concepts as 
if we were going to use _pre-existing web pages_ to represent concepts 
in the semantic web. In my opinion that's wrong because the semantics of 
those pre-existing web pages will be way too vague. Clarifying semantics 
is the whole point of the semantic web. Therefore what is much more 
likely is that semantic web concepts will be represented by RDF 
documents which are explicit about what they represent. It won't be that 
you use GM's home page to represent GM and I use Ford's. Much more 
likely, we will both point use a URI hosted by NYSE designed 
_explicitly_ to represent Ford and GM as their stock symbols do.

Similarly, I don't think that the page that represents "me" (at least 
for FOAF purposes) is my HTML home page or SMTP address, but rather my 
FOAF.rdf page.

>     Perhaps one [web page] is more trusted than another, more timely,
>     more complete, or throws in fewer pop-up ads.  The user experience
>     is different on the two sites, yet as far as anyone can tell, the
>     sites are about exactly the same thing. Let's imagine the thing is
>     the Sun, and the locations are both mine. I declare
>     http://www.hawke.org/sun-a and http://www.hawke.org/sun-b to both
>     identify the Sun, and my server gives nice data at both addresses.

By definition they are two different resources. They may talk about the 
same real-world thing but who cares?

>...
>>From [3]: 
> 
>     It's hard to accept the idea that there is one thing identified by
>     each URI when no one can tell me anything about that thing, except in
>     trivial, made-up cases (like DanC's "this is a car" page).  What thing
>     is, as far as you can tell, identified by
>        http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
>        http://www.uroulette.com/      [ used to pick the others ]
>        http://www.avianavenue.com/
>        http://ont.net/karate          [ 404, but don't let that stop you ]
>        http://www.interactivemarketer.com/
>     ...? 

That's why you don't want to use pre-existing web pages (i.e. those 
designed without the goal of being semantically precise). Can you figure 
out what these URIs are about:

http://jibbering.com/foaf.rdf
http://www.fiil.org.uk/rdf/orig-rdf-examples/WOMDA-example.xml

Yes, there exist URIs with ambiguous underlying semantics. That's what 
the semantic web is supposed to solve. It can't presume the problem to 
be already solved as its starting point.

  Paul Prescod
Received on Monday, 3 February 2003 14:08:23 GMT

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