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Re: ISSUE VARY: Proposed wording

From: Koen Holtman <koen@win.tue.nl>
Date: Thu, 10 Jul 1997 19:35:38 +0200 (MET DST)
Message-Id: <199707101735.TAA10599@wsooti08.win.tue.nl>
To: Jeffrey Mogul <mogul@pa.dec.com>
Cc: frystyk@w3.org, http-wg@cuckoo.hpl.hp.com
Jeffrey Mogul:
>
>Proposed changes to Section 13.6, 4th Paragraph:
>
>RFC2068:
>
>    The Vary header field may also inform the cache that the
[...]
>
>Henrik proposed:
>
>    The Vary header field MUST also inform the cache that the
[...]

>Koen changed one word:
>
>    The Vary header field MUST also inform the cache *if* the

Reading this again, I just noticed that the change from `may' to
`MUST' also requires that the modifier `if the response is cachable'
be added.

So:

>I think the first part is still somewhat misleading.  How about:
>
>    If the representation was selected using criteria not limited to
>    the request-headers, then the server MUST include a "Vary: *"
>    header field in the response.

Change to '.. in the response if it is cachable'.

>    In this case, a cache MUST NOT use the response in
>    a reply to a subsequent request unless the cache relays the new
>    request to the origin server in a conditional request and the
>    server responds with 304 (Not Modified), including an entity tag or
>    Content-Location that indicates which entity should be used.
>
>As long as we are going to say MUST, we should be explicit about
>what the requirement is.
>
>-Jeff

Koen.
Received on Thursday, 10 July 1997 10:38:42 EDT

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