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

On 21/04/2011 5:29 PM, Ron Wheeler wrote:
> On 21/04/2011 1:46 PM, Jawahar Balakrishnan (JB) wrote:
>> If you are thinking that is is dynamic content with query strings then
>> it's not the case. the urls will look like a directory structured
>> static content but the back-end app server will translate the url and
>> fetch the appropriate content from the CMS (alfresco)
>>
> Very few CMS or portals use query strings to select content.
> Our portal does not.
>
> What software are you using? Perhaps you can get some actual
> experience from a current squid user.
>
You might get more help in the Alfresco forum.
There seems to be a specific Alfresco problem for which there seems to
be a solution.

http://forums.alfresco.com/en/viewtopic.php?t=11412

Ron

> Have you tried a test with squid?
>
> Ron
>> On Thu, Apr 21, 2011 at 1:30 PM, Ron Wheeler
>> <rwheeler_at_artifact-software.com> wrote:
>>> 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 Fri Apr 22 2011 - 00:24:44 MDT