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Re: Documents, Cars, Hills, and Valleys

From: Aaron Swartz <me@aaronsw.com>
Date: Mon, 29 Apr 2002 14:30:43 -0500
To: Tim Berners-Lee <timbl@w3.org>, "Sean B. Palmer" <sean@mysterylights.com>, Mark Nottingham <mnot@mnot.net>
CC: RDF-Interest <www-rdf-interest@w3.org>
Message-ID: <B8F30993.3397C%me@aaronsw.com>
On 2002-04-19 05:22 PM, "Tim Berners-Lee" <timbl@w3.org> wrote:

> If you say that an HTTP header identifies a car, and then a GET returns a
> picture, how do you refer to the picture?

We have to do this already! The thing you get back from an HTTP GET changes
over time and based on content negotiation. If you want to talk about a
specific set of bits you got back, we have a way to do it: you describe the
thing. Here's an example:

[ hash:md5 "e6d96502596d7e7887b76646c5f615d9" ;
  :source <http://example.org/car> ;
  :time "2002-04-29";
  :format "image/png" ] .

HTTP already describes generic concepts in this sense. Expanding these to
the realm of physical things doesn't seem very difficult.

>>> HTTP has a lot of sophisticated design for the rendering of
>>> generic documents.   To try and force it into swtp: functionality
>>> is a kludge which would ruin it.
>> Can you give an example? It seems to work pretty well for me.
> Well, how do you represent what I would say as
> [] a :standardsOrg;  :homepage <http://www.w3.org/>;
>   is ipr:opyRightHolder of <http://www.w3.org/>;
>   org:subGroup :tands, :wai, :df, :int, :arch.
> <http://www.w3.org>  :isolang "en.us";
>    http:representation [ in:contentType "text/html"; http:size "6576" ];
>    dc:creator [ con:mailbox <mailto:janet@w3.org> ].
> If the home page and the organization are the same,
> how does that work?
Well the first triple in your second example is clearly broken, because
HTTP's language-negotiation would allow one to get back <http://www.w3.org/>
representations in a variety of languages. But the basic idea is correct,
instead of describing the abstract concept, you describe the characteristics
of the thing you got back by a GET request. So:

<http://www.w3.org/Consortium/> a :standardsOrg;
    :homepage <http://www.w3.org/Consortium/index> .

    :contentType "text/html" ; :language "en" ;
    http:representation [ :size "6576"; ... ] .

[ "Aaron Swartz" ; <mailto:me@aaronsw.com> ; <http://www.aaronsw.com/> ]
Received on Monday, 29 April 2002 15:30:48 UTC

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