[squid-users] newbie: configuring squid to always check w/origin server

From: dukehoops <nikita_at_doppelganger.com>
Date: Thu, 16 Oct 2008 16:12:55 -0700 (PDT)

Hi,

I am a squid (and http 1.1 headers to be honest) newbie who'd really
appreciate help w/squid config and header attributes on the following:

I have a server serving images that change dynamically (same URL invoked at
different times may return different images). I would like the following
behavior:
1. browser sends image request to squid

2. on receiving request from browser, squid always validates with origin
server using an Etag (or simply asks for image if no Etag exists)

3. origin server compares Etag received from squid and either responds with
either
a) "yes, you're up to date" and sends no image data, or
b) sends image date with new Etag (to be used by squid during subsequent
requests in #2 above).

4. if 3a) then squid returns to browser image date from own cache.
if 3b) squid updates own cache with what origin server returned and returns
image to browser

FWIW, origin servers are several in a cluster behind a virtual domain

Possibly naive (and hopefully easy) questions:
1. With what headers should the origin server respond in 3a) and 3b)? In
latter case, it seems like something like "Cache-Control: must-revalidate",
not sure whether to use s-maxage=0 and/or maxage=0
2. What params should be used in squid config?

thanks a lot!
-nikita

-----
----------------
Nikita Tovstoles
vside.com
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Received on Thu Oct 16 2008 - 23:13:00 MDT

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