Re: [squid-users] Question about reverse proxy and Apache Expires headers

Matus UHLAR - fantomas wrote:
> On 20.12.08 14:01, Tom Williams wrote:
>
>> ExpiresByType image/jpeg M2592000
>>
>
>
>> So, for the type image/jpeg, the file is set to expire one month after
>> that last time it was modified. Cool. The problem is, when I update an
>> image before the month expire time has elapsed, the OLD image in the
>> Squid cache is returned instead of the updated image that is stored in
>> the directory. I'm sure this is related to a configuration issue in my
>> Squid installation but I'm not sure where to start researching it.
>>
>
> you set up images to expire after a month, and wonder that they don't expire
> before a month?
>
As strange as that sounds, basically yes. :) The reason I set the
expiration period for one month is I don't expect the images to change
frequently at all. However, if the image DOES change at some point
within that month time period, I would want the image to be refreshed.

I'm sure my understanding of this is wrong but I was thinking if I set
the images to expire after say one day or one week, Squid would purge
the image that was in the cache and request an updated copy of the
image. If the image isn't changing with much frequency, I wouldn't want
Squid to fetch a "fresh", yet unchanged, copy of the image with much
frequency. Since I set the expiration to be since the image was last
modified, I was thinking Squid would ask the server if the image had
changed and fetch a new copy if it did. If the image had not changed,
after a month it would purge the old image and fetch a new one. Now
that I've written that, that doesn't make much sense either.

So, how do the expires headers impact Squid's interaction with the web
server in a reverse proxy configuration?

Peace...

Tom
Received on Sun Dec 21 2008 - 17:34:18 MST