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Re: Question about the On Linking Alternative Representations TAG Finding

From: <noah_mendelsohn@us.ibm.com>
Date: Thu, 31 Jul 2008 14:12:10 -0400
To: Dan Connolly <connolly@w3.org>
Cc: kidehen@openlinksw.com, "T.V Raman" <raman@google.com>, Richard Cyganiak <richard@cyganiak.de>, seb@serialseb.com, tthibodeau@openlinksw.com, www-tag@w3.org
Message-ID: <OF76E2278F.571BE989-ON85257497.00637DE9-85257497.0063DD96@lotus.com>

I think the problem formulation is too vague.  Some authority "owns" all 
the resouces in question, and can make them whatever he/she/it wants them 
to be.  If the authority says: "this URI is specifically for a JSON 
version and only a JSON ", then conneg'ing to HTML seems an error.  If the 
resource owner says:  this is the URI to (another) generic resource that 
by the way defaults to a JSON representation, then the conneg to HTML is 
fine.  I think the Web architecture allows either, as long as the resource 
owner behaives consistently.  I agree with Dan that that specific examples 
in th e TAG finding pretty much imply the JSON-only, but those are offered 
as an example of good practice, not a requirement for compatibility with 
Web Architecture.  If you need lots of cross-linked generic resources that 
differ primarily in the default mime-type returned, I think that's OK, if 
perhaps a bit unusual.

Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142

Dan Connolly <connolly@w3.org>
Sent by: www-tag-request@w3.org
07/31/2008 01:12 PM
        To:     Richard Cyganiak <richard@cyganiak.de>
        cc:     "T.V Raman" <raman@google.com>, seb@serialseb.com, 
www-tag@w3.org, kidehen@openlinksw.com, tthibodeau@openlinksw.com, (bcc: 
Noah Mendelsohn/Cambridge/IBM)
        Subject:        Re: Question about the On Linking Alternative 
Representations TAG     Finding

On Thu, 2008-07-31 at 17:43 +0100, Richard Cyganiak wrote:
> Let's say I have
> /resource      (generic information resource with HTML and JSON 
> variants)
> /resource.html (a HTML specific URI)
> /resource.json (a JSON specific URI)
> Now let's say I request /resource.json with an Accept header of 
> "Accept: text/html". What should happen?
> One opinion is that the JSON should be served anyway, because the URI 
> identifies a specific variant.
> Another opinion is that the HTML should be served, or redirected to, 
> because that's what the client asked for and the server has it 
> available.
> (A third opinion is that 406 should be answered, as suggested by 
> Sebastien.)

Either a 406 or a 200 with JSON is consistent with the
claim that /resource.json is JSON-specific.
Serving a 200 with text/html is not.

A redirect might be reasonable... it feels like a bit of a stretch.

> What I'm asking for is simply a clarification of the advice in the 
> spec. Did you intend that there be content negotiation on the 
> representation_i URIs?

I didn't; re-reading the text, I don't see any other way
to read it.


Dan Connolly, W3C http://www.w3.org/People/Connolly/
gpg D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Thursday, 31 July 2008 18:11:30 UTC

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