I know this has been a long running debate in this group and I think I
understand the claims and theory on both sides. But to check as I see
the question if I have control of both sides (and have perfect systems
in between) then having an expiration string would be the best answer.
The owner of the data would know when it expires and the caches would
give me optimal performance. If the server does not expire the
information and/or the systems in-between are not set up right, then
the cached information could be incorrect. In that case I would have
to use a unique string to force freshening of the data. This, however,
could lead to excessive load on the various caching systems, from the
proxies to the client itself.
Assuming the above is substantially correct I have three questions.
First, does anyone have a reference to some tests on proxy
configuration? I saw people say that they can/are misconfigured, but I
would like to see something that gives me an idea of how prevalent
that is.
Second, as a follow up to that, does anyone have any ideas of what is
the realistic length of time things tend to stay in various caches
(proxy, client, etc.)? I know the answer could be "forever", I am just
wondering about expectation. Are we talking about minutes, hours,
days?
Third, couldn't the client check the expires itself and then decide on
asking a second time with a unique string? Yes, I understand that is
probably worthwhile for any/most situations, I am just trying to
understand this fully for myself.
Thanks to all.
--
Matt Silberstein
Do something today about the Darfur Genocide
http://www.beawitness.org
http://www.darfurgenocide.org
http://www.savedarfur.org
"Darfur: A Genocide We can Stop"