Re: [squid-users] Re: Squid Cache flush

If you google "squid dynamic content" you will find that by default
squid does not cache dynamic content.
If it did, it would be useless as a proxy server since that would make
almost all dynamic sites unusable.

There are lots of instructions about how to trick squid into caching
content that it (and the web servers it proxies) think is dynamic but
you know is not.
Youtube videos is one example where the web server says the content is
dynamic but in fact humans know that it is not.

I think that a simple test will allow you to see that your CMS content
will get handled correctly.

What are you using for CMS servers?
Perhaps someone can give you first-hand experience or a web site to visit.
I have never had to do anything to Apache and Wordpress to get it to
work properly.

Don't forget that Squid and the web server can talk to each other
without actually shipping content. The HTTP protocol has lots of
different messages that can be quickly exchanged to make decisions about
whether squid actually needs new content.

Ron

On 21/04/2011 12:31 PM, Jawahar Balakrishnan (JB) wrote:
> It is all dynamic content going forward
>
> scenarios where a cache flush would be required
>
> 1) an article is updated
> 2) category is updated with a list of articles.
>
> we syndicate content to abut 150 partner and will have same
> article/category with a different URL doesn't squid cache based on the
> url?
>
> when you update content on your cms - how does squid know to update it's cache?
>
> JB
>
> On Thu, Apr 21, 2011 at 12:10 PM, Ron Wheeler
> <rwheeler_at_artifact-software.com> wrote:
>> Are you sure that you need to do this?
>> Squid should be able to tell the difference between static and dynamic
>> content.
>>
>> We have a dynamic JSR-168/268 portal based on Tomcat and Jetspeed sitting
>> behind Apache and Squid and we have never had to intervene with Squid for 3
>> years.
>> We also have lots of Wordpress CMS sites.
>>
>> The user gets the latest information on every page load regardless of the
>> URL being the same.
>>
>> What exactly would cause you to trigger a flush of the cache?
>>
>> Ron
>>
>>
>> On 21/04/2011 11:30 AM, Jawahar Balakrishnan (JB) wrote:
>>> I would rather not do a restart of anything unless absolutely required
>>>
>>> Here are the challenges we face
>>>
>>> 1) We are trying to deploy Suqid as a reverse-proxy in front of a CMS
>>> 2) We want to trying find a balance between keeping the content fresh
>>> without affecting performance by frequently expiring content.
>>>
>>> Our current reverse proxy solution allow us to flush the entire cache
>>> without having to restart but in limited testing Squid seemed to
>>> perform much better and we would prefer to use Squid but still retain
>>> the functionality of being able to flush the entire cache periodically
>>> via cron or when in case of an emergency.
>>>
>>> Cache-control headers are fine and will work in case of limited number
>>> of objects.
>>>
>>> Thanks
>>> JB
>>>
>>>
>>> On Tue, Apr 19, 2011 at 7:27 PM, Amos Jeffries<squid3_at_treenet.co.nz>
>>> wrote:
>>>> On Tue, 19 Apr 2011 11:14:55 -0400, Jawahar Balakrishnan (JB) wrote:
>>>>> I am looking to deploy Squid as a reverse proxy and i had couple of
>>>>> questions. We currrently use Bluecoat and Sun Web proxy and i am able
>>>>> to do the following things
>>>>>
>>>>> 1) How would i flush objects from cache?
>>>> The whole lot:
>>>> http://wiki.squid-cache.org/SquidFaq/ClearingTheCache
>>>>
>>>> or individually via:
>>>> HTTP "PURGE" requests
>>>> HTCP "CLR" requests
>>>>
>>>> squidpurge tool commands.
>>>>
>>>>
>>>>> 2) Can i flush the entire cache without restarting Squid?
>>>> Yes ... but it takes a LONG time to do N objects individually.
>>>> Restart without a cache to load takes milliseconds.
>>>>
>>>>> 3) Can i set the configuration to expire objects at a certain time
>>>>> every day regardless of when the object was cache during the previous
>>>>> 24 hours?
>>>> Use of the Expiry and Cache-Control mechanisms properly can do just about
>>>> anything. Correct use will make all proxies not just your reverse one
>>>> handle
>>>> the site fine and remove a lot of customer problems.
>>>>
>>>> Objects which arrive with header "Expires: XX" will expire at XX
>>>> timestamp
>>>> and be replaced on their next use.
>>>>
>>>>
>>>>
>>>> Amos
>>>>
>>>>
>>
Received on Thu Apr 21 2011 - 17:30:08 MDT