[Osmf-talk] Encouraging the expansion of GeoDNS enabled tile serving?

Tom Hughes tom at compton.nu
Thu Nov 15 13:42:52 UTC 2012


On 15/11/12 13:28, Joseph Reeves wrote:

> > What sort of documentation? You seem to have already found most of
> > the relevant stuff.
>
> Ok, I didn't know if there was any additional technical documentation or
> any more usage stats available. Presumably the DNS bit is pretty
> straightforward, and members of the CDN just mirror the original OSM
> database.

There's no mirroring as such - the servers just run squid with the 
primary tile server as the upstream server.

> I would be interested in how a user's tileserver is determined, however;
> if I'm physically halfway between Sjöbo and Brisbane is my tileserver
> decided by a calculated round-trip time to a server, or does it rely on
> a simple rule such as "you're in India, so your tiles come from Sweeden"?

Basically it is determined by this script:

   http://git.openstreetmap.org/dns.git/blob/HEAD:/bin/mkgeo

based on the rules we specify:

   http://git.openstreetmap.org/dns.git/blob/HEAD:/src/tile.openstreetmap

So we can restrict a server to only serve specific countries no matter 
what, as we have for example with the Brisbane server.

All else being equal the final determinant is distance.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://compton.nu/




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