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Question on the boundaries of content negotiation in the context of the Web of Data

From: Michael Hausenblas <michael.hausenblas@deri.org>
Date: Thu, 12 Feb 2009 12:29:07 +0000
To: <www-tag@w3.org>
Message-ID: <C5B9C693.1D83%michael.hausenblas@deri.org>


Dear TAG members, dear subscribers,

I would like to ask you about your opinion on the following scenario. Please
note that (1) though I'm a member of the W3C Media Fragments WG I speak only
for myself, and (2) that all URIs used in the following are dereferenceable
and made out of 100% recycled electrons.

Given three URIs, namely,

<http://sw-app.org/sandbox/house>

<http://sw-app.org/sandbox/house.png>

<http://sw-app.org/sandbox/house.ttl>

is it 'allowed' (that is, does it break the Web architecture) if one does
the following:

$curl -I -H "Accept: image/png" http://sw-app.org/sandbox/house
HTTP/1.1 200 OK
Date: Thu, 12 Feb 2009 12:12:39 GMT
Server: Apache/2.2.3 (CentOS)
Content-Location: house.png
Vary: negotiate,accept
TCN: choice
Last-Modified: Thu, 12 Feb 2009 11:54:07 GMT
ETag: "5c0fd-2deb-462b760a7f5c0;462b77ce8a040"
Accept-Ranges: bytes
Content-Length: 11755
Connection: close
Content-Type: image/png

$ curl -I -H "Accept: text/turtle" http://sw-app.org/sandbox/house
HTTP/1.1 200 OK
Date: Thu, 12 Feb 2009 12:13:01 GMT
Server: Apache/2.2.3 (CentOS)
Content-Location: house.ttl
Vary: negotiate,accept
TCN: choice
Last-Modified: Thu, 12 Feb 2009 11:54:06 GMT
ETag: "5c0fc-173-462b76098b380;462b77ce8a040"
Accept-Ranges: bytes
Content-Length: 371
Connection: close
Content-Type: text/turtle

Please note that I don't ask if this works. It does. Obviously. The
question, to put it in other words, is: is the PNG *representation* derived
via conneg from the generic resource <http://sw-app.org/sandbox/house>
equivalent to the RDF in Turtle?

If not, why not? If it is, can you please point me to a finding, note, a
specification, etc. that 'normatively' defines what 'equivalency' really is?

Cheers,
      Michael

-- 
Dr. Michael Hausenblas
DERI - Digital Enterprise Research Institute
National University of Ireland, Lower Dangan,
Galway, Ireland, Europe
Tel. +353 91 495730
http://sw-app.org/about.html
Received on Thursday, 12 February 2009 12:29:50 GMT

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