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Re: Minor fixes to draft 05

From: Jeffrey Mogul <mogul@pa.dec.com>
Date: Wed, 03 Jul 96 15:48:29 MDT
Message-Id: <9607032248.AA03556@acetes.pa.dec.com>
To: jg@w3.org
Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Jim Gettys reminded me about this one:
    ***************
    *** 5232,5238 **** [14.6 Age, last para]
      If a cache receives a value larger than the largest positive integer it
      can represent, or if any of its age calculations overflows, it MUST
      transmit an Age header with a value of 2147483648 (2^31). HTTP/1.1
    ! caches MUST send an Age header in every response. Caches SHOULD use an
      arithmetic type of at least 31 bits of range.
      
      
    --- 5229,5236 ----
      If a cache receives a value larger than the largest positive integer it
      can represent, or if any of its age calculations overflows, it MUST
      transmit an Age header with a value of 2147483648 (2^31). HTTP/1.1
    ! caches MUST send an Age header field in any response obtained from
    ! its own cache. Caches SHOULD use an
      arithmetic type of at least 31 bits of range.
      
This change (only requiring Age on responses taken from a cache)
breaks the clock-deskewing properties of the original Age design.
The problem comes when a pre-1.1 cache is in the path and has
held onto the response for a while.  It's safest to add the Age
header as soon as possible, since it reduces the chances that
a skewed clock could result in incorrect comparisons.

-Jeff
Received on Wednesday, 3 July 1996 15:59:25 EDT

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