[Openstreetmap-dev] Re: [Openstreetmap] cache of editor applet background?
erjohan at gmail.com
Wed Jan 25 08:35:49 GMT 2006
On 1/24/06, Erik Johansson <erjohan at gmail.com> wrote:
> On 1/24/06, Mikel Maron <mikel_maron at yahoo.com> wrote:
> > This would be another way to do it. But it would add unneeded complexity on the client? And overhead with
> > ETAG generation and requests.
> Short answer no.
So I've tested, and ETags does not work for me, works great for
browser clients but not for squid (YMMV). But If-Not-Modified-Since
header works wonders, and compare that value to the one you have.
To get it to work set Squid to rewrite reloads to a request with a
If-Modified-Since header, now depending on how the expire date is
set squid will ask for updates or just serve the image from cache.
When Squid asks for update it will send a request with an IMS header,
and when it receives a response " HTTP/1.1 304 Not Modified" it will
send a cached copy back to the client.
Downside is; a cache hit in squid takes 60ms and a IMS-hit to apache
takes upto 800ms.
Sending this back to the client, the only important thing is that the
datestamp needs to change when the data changes.
 I don't know how the "Min Precantage Max" in refresh pattern
works, I used the more bruteforce "reload_into_ims on" but something
like this should work:
refresh_pattern tile.openstreetmap.org 60 20% 10080 reload-into-ims
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