Re: [squid-users] HTTP Headers & caching

On Tue, 2 Aug 2005, Bruce Badger wrote:

> HTTP/1.x 200 OK
>
> Cache-Control: public, max-age=0

Why public?

> So, my expectation was that the max-age would mean that no cached
> responses would be served - clearly wrong.

public says the response is good for all users even if the request
contained authentication credentials. This should only be used on public
static content which does not need any protection and may be cached at any
level.

max-age says that proxies must attempt to revalidate the page before
sending the response to the client. If this revalidation is not successful
the proxy MAY send the original response (and should in such case include
a Warning header about the fact which Squid currently does not, and no
clients cares about anyway). no-cache is a shorthand for max-age=0 with
the exception that many implementations (Squid included) handles no-cache
as a synonym for no-store.

> Could someone point out my mistake, and perhaps point me to the place
> in the mountain of documentation I should be looking?

If you have pages which are user specific then you SHOULD use
"Cache-Control: private", not "public".

Good background reading is HTTP/1.1 RFC 2616 "4.9.1 What is Cacheable" and
"4.9.2 What May be Stored by Caches". This explains the concepts pretty
well I think.

Regards
Henrik
Received on Fri Aug 05 2005 - 04:58:05 MDT