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Re: Is 303 really necessary?

From: David Booth <david@dbooth.org>
Date: Sat, 06 Nov 2010 16:42:00 -0400
To: Ian Davis <me@iandavis.com>, Linked Data community <public-lod@w3.org>
Message-ID: <1289076120.5492.8995.camel@dbooth-laptop>
> > > httpRange-14 requires that a URI with a 200 response MUST be an IR;
                                                         ^^^^^^^
Not quite.  The httpRange-14 decision says that the resource *is* an IR:
http://lists.w3.org/Archives/Public/www-tag/2005Jun/0039 

> > >  a URI with a 303 MAY be a NIR.
> > > 
> > > Ian is (effectively) suggesting that a URI with a 200 response MAY
> > > be an IR, in the sense that it is defeasibly taken to be an IR,
> > > unless this is contradicted by a self-referring statement within
> > > the RDF obtained from the URI.

To be clear, Ian's toucan URI *does* identify an information resource,
whether or not it *also* identifies a toucan:

  $ curl -I 'http://iandavis.com/2010/303/toucan'
  HTTP/1.1 200 OK
  Date: Sat, 06 Nov 2010 20:05:57 GMT
  Server: Apache/2.2.8 (Ubuntu) DAV/2 SVN/1.4.6 PHP/5.2.4-2ubuntu5.10
with Suhosin-Patch mod_wsgi/1.3 Python/2.5.2
  Content-Location: toucan.rdf
  Vary: negotiate
  TCN: choice
  Last-Modified: Fri, 05 Nov 2010 09:24:27 GMT
  ETag: "264186-403-4944ad745a8c0;4944ad754eb00"
  Accept-Ranges: bytes
  Content-Length: 1027
  Content-Type: application/rdf+xml; qs=0.9

Thus, Ian has created an ambiguity by returning a 200 response.  There
is nothing fundamentally wrong with this, as ambiguity of resource
identity is inescapable anyway, and we just have to learn to deal with
it.  However, for those applications that need to distinguish between
the toucan and its web page, Ian is effectively suggesting the
*heuristic* that if the content served in the 200 response says that the
URI identifies a toucan, then the app should ignore the fact that the
URI also identifies a web page, and treat the URI as though it *only*
identifies the toucan.



-- 
David Booth, Ph.D.
Cleveland Clinic (contractor)
http://dbooth.org/

Opinions expressed herein are those of the author and do not necessarily
reflect those of Cleveland Clinic.
Received on Saturday, 6 November 2010 20:42:30 UTC

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