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Re: New document on "Simple hit-metering for HTTP"

From: Koen Holtman <koen@win.tue.nl>
Date: Sat, 10 Aug 1996 16:44:42 +0200 (MET DST)
Message-Id: <199608101444.QAA19602@wsooti04.win.tue.nl>
To: Jeffrey Mogul <mogul@pa.dec.com>
Cc: koen@win.tue.nl, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com, mogul@pa.dec.com
Jeffrey Mogul:
>
>    This is very interesting...  I wrote earlier that we need to
>    distinguish between two kinds of demographic data:
>    
>    1) Hit counts
>    
>    2) User's Referer field, IP address, User-Agent field, ...
>    
>    The proposed hit counting mechanism allows you to get 1) for all user
>    agents without cache busting, but not 2).  You seem to predict that
>    most advertising sites will want to have 2) in future.  That would
>    make the the proposed hit counting mechanism pretty ineffective at
>    reducing cache busting.
>
>This is not true.  For any field that appears in the client's
>request headers (i.e., not "IP address" but definitely User-Agent),
>you can obtain counts without cache-busting (which I would
>define as "completely disabling caching").

That is not my definition of cache busting.  The cache busting done
for demographics reasons will be of the `max-age=0' kind, which allows
conditional GETs, rather than the `no-cache' kind.

I can't see much difference, as far as efficiency is concerned,
between your proposed use of the Vary header and max-age=0 cache
busting.  Both as are inefficient, but at least max-age=0 is
inefficient in a non-complex way.

To do a good job at giving demographers the complete request data
(including client IP address) they seem to want, a completely
different mechanism is needed.  Why don't you specify something that
lets origin servers tell caches to log certain request characteristics
and report them in a future request?  The logging overhead for such a
mechanism seems to be about the same as for your Vary mechanism.

Koen.
Received on Saturday, 10 August 1996 07:47:56 EDT

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