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Re: Content negotiation example needed.

From: Nir Dagan <nir@nirdagan.com>
Date: Sat, 11 Sep 1999 20:09:11 -0400
Message-Id: <199909120007.UAA14925@dark.brown.edu>
To: thatch@us.ibm.com, max@wide.ad.jp
Cc: w3c-wai-gl@w3.org
At 06:21 PM 9/11/99 -0500, thatch@us.ibm.com wrote:
>
>
>I followed up the example that Max suggested (
>http://www.w3.org/1999/08/smil-pressrelease), setting Netscape's language
>preference to French (fr) and received the following message. Seems like
>"negotiation" is a little strong a concept for whats going on.
>
>>Message when language set to French:
>>Not Acceptable
>>An appropriate representation of the requested resource
>/1999/08/smil-pressrelease
>>could not be found on this server.
>>Available variants:
>>   smil-pressrelease.html.en , type text/html, language en, charset
iso-8859-1
>>   smil-pressrelease.html.ja , type text/html, language ja, charset
iso-2022-jp
>
>
>Is this HTTP protocol? It seems as though: if you have *no* language
specified,
>server delivers a default. If you have a language defined, the server
tries to
>deliver that language version, and presents a list of language editions
>available otherwise. Is that the net of this content negotiation.

Sort of. According to RFC 2616 (HTTP/1.1 latest dratf standard)
When a client specifies languages that are not available the server can do
two different things:
1. return a 406 error message listing the avialable alternatives.
   This is what the example does. HTTP does not specify exactly how to
write the HTML.
   In my view the returned document could be more human friendly. E.g.:

Choose your preferred language
The document you requested is not available in the language(s) the 
you most prefer.

Available versions:
   SMIL press release (English)
   SMIL press release (Japanese) [this should be written in Japanese; both 
                                  should be active links]

2. The second option permitted by the spec. is to return the document in
some default 
   language (as the server does if no language priorities were stated by
the client)

It is up to the content provider to decide, which option to take, what is the 
default language, and how to write the 406 error message.

===================================
Nir Dagan
Assistant Professor of Economics
Brown University 
Providence, RI
USA

http://www.nirdagan.com
mailto:nir@nirdagan.com
tel:+1-401-863-2145
Received on Saturday, 11 September 1999 20:08:03 GMT

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