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Re: ISSUE-57: The use of HTTP Redirection

From: Richard Cyganiak <richard@cyganiak.de>
Date: Wed, 29 Aug 2007 14:15:18 +0200
Message-Id: <D0B4AC8B-188C-4BA9-B4E8-5B49E0382987@cyganiak.de>
Cc: "Tim Berners-Lee" <timbl@w3.org>, "Ed Davies" <edavies@nildram.co.uk>, "Technical Architecture Group WG" <www-tag@w3.org>
To: "Booth, David (HP Software - Boston)" <dbooth@hp.com>


On 28 Aug 2007, at 22:19, Booth, David (HP Software - Boston) wrote:

>
>> From:  Tim Berners-Lee
>> [ . . . ]
>>
>> Often, people use the term "non-information resource" to mean "some
>> resource, not necessarily an information resource".
>
> Good Lord, I hope not!  Please chastise anyone who is doing so!  We  
> have
> enough chaos without changing the English meaning of "non-".

An example perpetrated by, uh, me:

[looking at an HTTP response] “This is a 303 redirect, which tells  
the client that the requested resource is a non-information resource,  
and its associated description can be found at the URI given in the  
Location: response header.” [1]

This is incorrect, because 303 doesn't really tell us *anything*  
about the nature of the resource, except that associated information  
might be found somewhere else.

My incorrect statement was motivated by the question why hash URIs or  
303 URIs or 200 URIs should be used in a particular case. Usually,  
the answer goes like this: If you have an IR, you can use 200. If you  
have a non-IR, you must use 303 or a hash URI. Unfortunately, that's  
not the whole story. There is this grey area where you *may* or even  
*must* identify normal IRs using hash URIs or 303 URIs. That grey  
area is a mess.

There's a lot of discussion currently about the distinction between  
IRs and non-IRs. Is it about “essential characteristics conveyable in  
a message”, about “can we attach an HTTP endpoint to it”, about  
“document-ness”?

To me, this all misses the point. Even if we can nail down objective  
criteria to distinguish these buggers, this will *still* not tell us  
if we have to serve them up using 303/hash or 200.

So, can anyone shed light on this? If I mint a URI, what's the  
criterion for setting up 200 vs. 303/hash? Keep in mind Tim's  
example: CERN could set up a 303 redirect from some early-day WWW  
URIs of historic interest, to a “museum page” hosted at today's W3C  
site.

Richard

[1] http://sites.wiwiss.fu-berlin.de/suhl/bizer/pub/ 
LinkedDataTutorial/#ExampleHTTP



>
>
>
> David Booth, Ph.D.
> HP Software
> +1 617 629 8881 office  |  dbooth@hp.com
> http://www.hp.com/go/software
>
> Opinions expressed herein are those of the author and do not represent
> the official views of HP unless explicitly stated otherwise.
>
>
>
Received on Wednesday, 29 August 2007 12:16:16 GMT

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