Re: [squid-users] Squid as Reverse Proxy - Backend Server Issues

Hi,

On Thu, Jun 5, 2008 at 2:15 AM, Henrik Nordstrom
<henrik_at_henriknordstrom.net> wrote:
> tor 2008-06-05 klockan 00:19 +0800 skrev howard chen:
>> 1. Is it true Squid will only use the Last Modified and Cache Control
>> header for caching,
>
> Yes.
>
>> other headers are not important in my setup?
>
> Well.. don't send conflicting Expires or "Pragma: no-cache" headers..
>
>> 2. I found that Squid will not consult the backend for updating the
>> Last Modified value and sometimes send out 304 directly. So is that if
>> my file has changed in my backend, I need to PURGE the Squid?
>
> Or wait until the freshness expires. Or issue an request with
> Cache-Control: max-age=0 to force the freshness to expire "now". When
> the object freshness has expired Squid will use Last-Modified to query
> the backend to see if there has been any changes.

Thanks first.

The following is my understanding (correct me if I am wrong)

1. When Apache send Expire =... thru Squid, if it is future time, then
client won't issue any request to the server side again for the same
resource (unless you press F5 to issue max-age=0), so mod_expire has
nothing to do with squid, it is client level stuffs.

2. Squid caching basically depends on Last Modified header (maybe also
Etag, but I have disabled all)

Now my problems are:

1. If I only send Last Modified, but no Expire, how do Squid know the
freshness time if it don't contact the backend? Or should I always
send Expire with Last Modified or maybe use refresh plattern / PURGE /
set max-age=0 ?

Thanks.

Howard
Received on Wed Jun 04 2008 - 18:49:03 MDT