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Re: Offline mode with a parent cache doesn't work

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londoner1@xxxxxxxxxxxx wrote:
On Thu, 25 Jun 2009 05:44:24 -0700 Amos Jeffries <squid3@xxxxxxxxxxxxx> wrote:
londoner1@xxxxxxxxxxxx wrote:
Hi,

I am trying to setup a local squid cache on my laptop so that I
can
browse intranet pages when I am on a plane and don't have
network
connection.

I am therefore using the squid offline_toggle option via the 'squid3client mgr:offline_toggle' command.

However, I am finding that pages are not being cached when I
have
my Office proxy set as a parent to my local one.

I am running ubuntu hardy with squid 3 STABLE.1 ubuntu package
on
my local machine, with a parent proxy set using the following
lines
in my squid.conf:

cache_peer proxy.nectech.co.uk parent 8080 0 no-query
prefer_direct off

PS: The above two lines came from Squid wiki here:
http://wiki.squid-cache.org/SquidFaq/ConfiguringSquid#head-
c050a0a0382c01fbfb9da7e9c18d58bafd4eb027

My approach to test this is as follows:

1 Set firefox to my localhost:3128 proxy
2 Start squid in online mode and browse to a website.
3 Close firefox
4 Set local squid into offline mode using 'squid3client mgr:offline_toggle' 5 Pull out the Network cable (to simulate being on a plane) 6 Reopen firefox and browse to same site as in step 2.
After step six, the page does not load and eventually times out.

If i take out the parent cache lines, the offline mode will
work.
Please can anyone help?
'offline_mode' means that Squid no longer attempts page validation and fetching of new pages. It does not means supplying content known to be past expiry.

Hi Amos, Ok, please forgive me if I dont understand you correctly: you are saying that the local squid cache is NOT returning me the page that i previously went to a few minutes ago because it thinks it has expired?

Yes. From the info provided I believe that is what is happening.


why would it be expired that quickly? and yet not be expired if my local squid cache does not use the parent cache?

HTTP contains things called If-Modified-Since requests. When squid thinks something is expired it either uses them or a new request to check for new content. Sometimes an IMS request sens back "no hasn't chaged" so Squid updates its information and sends you the object again.

It's probably that the HTML part of the page has a short expiry time but does not actually change (ie a dynamically created page).

Even if all the images etc on the page are available for months, without an HTML part to say how they are displayed the page wont show up.



Also, a poster on the following blog mentioned that squid offline mode ignores expiry data for cached items when in offline mode. Is this not the case in latest squid 3 versions?

http://people.w3.org/~dom/archives/2006/09/offline-web-cache-with-
squid/

ps I appreciate your help on the subject.

Mark who replied there and others have made a lot of improvements to the expiry and IMS sections of the latter Squid 2.6 releases and 2.7.

The Squid-3 code in the same areas is a lot older with not all of their changes ported over. So I believe it would behave differently. Though I'm not fully clued up on the finer grains of whats going on there.

Amos
--
Please be using
  Current Stable Squid 2.7.STABLE6 or 3.0.STABLE16
  Current Beta Squid 3.1.0.8

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