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Re: Confusion about Age: accuracy vs. safety

From: Roy T. Fielding <fielding@liege.ICS.UCI.EDU>
Date: Wed, 04 Sep 1996 15:44:27 -0700
To: Anselm Baird-Smith <abaird@w3.org>
Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Message-Id: <9609041545.aa20705@paris.ics.uci.edu>
> I can speak for myself here: as I am not as wise as you guys, and as I
> don't have much time for discussions, I did implement *exactly* (as
> faithfully as possible - see code below), Jeff's pseudo code.

Anselm, I believe that what you have implemented is just the calculation
of the Age upon receipt, right?  The question is: does the proxy code
add an Age header field (or to the value of an existing Age header)
when it forwards a message not from its own cache?

There is nothing wrong with the calculation of Age upon receipt.  The
problem would be if intermediaries added to the Age value (the age as
perceived by the outbound clients) when no aging occurs. If they do add
to the age, then Age becomes meaningless as a mechanism for ensuring a
lower bound in the presence of clock skew.

 ...Roy T. Fielding
    Department of Information & Computer Science    (fielding@ics.uci.edu)
    University of California, Irvine, CA 92697-3425    fax:+1(714)824-4056
    http://www.ics.uci.edu/~fielding/
Received on Wednesday, 4 September 1996 15:56:27 EDT

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