[Openstreetmap] applet speedup

[Mikel Maron]

<!-- DIV {margin:0px} --> From: Simon Hewison <simon at zymurgy.org>
> 
> When it does grab the Landsat tiles, does it do it through the squid 
> proxy cache? Ditto for the WMS server before compositing the static 
> maps. That way, the Landsat will be in something that is a bit quicker 

Yes and yes. Both requests go through squid, and on to mapserver.

I'm setting up a purely Landsat cache on landsat.openstreetmap.org (this is the dev server).
There's plenty of disk, and the cache needs to be configured somewhat differently.
The connection between tile and dev is very fast.

> Even if Landsat server gives stupidly short HTTP expiry headers, it 
> would be possible to fake that and set an expiry time of something like 
> a month, and get squid to cache it, since Landsat doesn't change that often.

Yes, the Expires headers are something less than 24 hours. This can be overriden in squid.
http://wiki.squid-cache.org/config/refresh_pattern

I was thinking of setting the expiry time to something very close to forever (maybe a couple years, which seems like forever.) The cache can be more or less permanent. There are no plans for OnEarth to update their Landsat imagery in the foreseeable future. If it ever became a necessity to update, there are ways to invalidate the cache; or rather selectively invalidate the cache to prevent slow response times while the cache is rebuilt.

Mikel






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