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From Florian Zumbiehl <>
Subject Re: mod_deflate Vary header
Date Sat, 05 Nov 2005 12:28:38 GMT

> > To put this straight: I was thinking about web servers behind
> > V.90/ISDN/ADSL lines where _that_ line  usually will be the bottleneck
> > on any connections to the outside world and about caching proxies
> > in that outside world ...
> Yes, but if you do compression because some of your clients have low bandwith
> connections (but are capable of receiving compressed pages) and access your
> server via a proxy then not sending the Vary header can "poison" the cache in a way
> you do not want. Because if the client which causes the proxy to cache the response
> is not capable to receive compressed pages will cause the proxy to cache *only* the
> uncompressed version of the page.

The whole point is I don't do compression because of any _clients'_
connections, but because of the _server's_ connection! If the server's
connection usually is far slower than the client's connection (like
with a server behind a V.90 modem, which would be 33.6 kb/s upstream
with considerable latency), it (1) would be faster for the vast majority
of clients to get an uncompressed copy from their ISP's cache rather than
a compressed one from the original server and (2) even if it wasn't, it
still might save traffic and thus money for the server operator.

Cya, Florian

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