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Re: Uniform access to descriptions

From: Tim Berners-Lee <timbl@w3.org>
Date: Sat, 12 Apr 2008 09:02:20 -0400
Cc: Pat Hayes <phayes@ihmc.us>, noah_mendelsohn@us.ibm.com, Jonathan Rees <jar@creativecommons.org>, Phil Archer <parcher@icra.org>, "Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>, "www-tag@w3.org WG" <www-tag@w3.org>
Message-Id: <76F0CFCA-F83B-49F5-B340-26C1C5AF1595@w3.org>
To: wangxiao@musc.edu


On 2008-04 -12, at 05:37, Xiaoshu Wang wrote:
> I think TAG's httpRange-14 is the following logic.
> Representation=Resource if HTTP=200.

The relation ship is not equality.   It is 'representation'.  The  
resource is an abstract document.
The thing returned, with a 200 response, is a tag:representation of  
the document,

Loosely, It is a representation using some form of languages and  
encoding of the meaning of the document.   Some languages may be  
better at giving ht meaning than others.  Also some languages can be  
more easily assimilated by  a program than others.  But the  
architecture of the web relies on the fact that if I find out some  
information from a document with URI x, then I can quote x to someone  
else and expect them to be able to get the same information.  Even if  
they are using different hardware and software and have a different  
screen size, and so on.   They might get degraded information through  
conneg: for example, if they can only get RDF and there is information  
on the HTML version which isn't encoded in the RDF version, then there  
is loss, and the server should only do conneg if really the publisher  
is quite happy with someone getting either conneged representation back.

Conneg MUST NEVER be used to select between quite different documents,  
or between a document and another document about the first document.

That is the intent of the relation 'representation', as in 'the HTTP  
200 response is a representation of the document'.

('document' is called 'InformationResource' in the AWWW)

> But Conneg breaks either the "equal" sign or the if clause.
> Xiaoshu
Received on Saturday, 12 April 2008 13:02:52 UTC

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