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Re: Issue 39: proposed example for varying the etag based on conneg

From: Nathan <nathan@webr3.org>
Date: Thu, 25 Mar 2010 23:39:27 +0000
Message-ID: <4BABF42F.302@webr3.org>
To: Julian Reschke <julian.reschke@gmx.de>
CC: HTTP Working Group <ietf-http-wg@w3.org>
only feedback I can give is my immediate question:

  can they share a weak entity tag?

many regards,

nathan

Julian Reschke wrote:
> Hi,
> 
> here's a proposal that would partly address
> <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/39>; after the
> introduction to entity tags, let's add an example that makes it crystal
> clear that entity tags may not be shared between responses negotiated on
> Accept-Encoding:
> 
> -- snip --
> 2.1.  Example: Entity Tags varying on Content-Negotiated Resources
> 
>    Consider a resource that is subject to content negotiation (Section 4
>    of [Part3]), and where the representations returned upon a GET
>    request vary based on the Accept-Encoding request header field
>    (Section 5.3 of [Part3]):
> 
>    >> Request:
> 
>      GET /index HTTP/1.1
>      Host: www.example.com
>      Accept-Encoding: gzip
> 
> 
>    In this case, the response may use the gzip Content Coding or not.
>    If it does, it might look like that:
> 
>    >> Response:
> 
>      HTTP/1.1 200 OK
>      Date: Thu, 26 Mar 2010 00:05:00 GMT
>      ETag: "123-a"
>      Content-Length: 70
>      Vary: Accept-Encoding
>      Content-Type: text/plain
> 
>      Hello World!
>      Hello World!
>      Hello World!
>      Hello World!
>      Hello World!
> 
>    A variant that does use gzip Content Coding would be:
> 
>    >> Response:
> 
>      HTTP/1.1 200 OK
>      Date: Thu, 26 Mar 2010 00:05:00 GMT
>      ETag: "123-b"
>      Content-Length: 43
>      Vary: Accept-Encoding
>      Content-Type: text/plain
>      Content-Encoding: gzip
> 
>      ...binary data...
> 
>       Note: Content Codings are a property of the response entity, thus
>       affect the Entity Tag. An alternative are Transfer Codings
>       (Section 6.2 of [Part1]) which apply only the transfer of the
>       message, and thus do not require assigning distinct entity tags.
> 
> -- snip --
> 
> (<http://trac.tools.ietf.org/wg/httpbis/trac/attachment/ticket/39/i39.diff>)
> 
> 
> Feedback appreciated,
> 
> Julian
> 
> 
> 
Received on Thursday, 25 March 2010 23:40:13 GMT

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