> From: Yantisa Akhadi [mailto:yant...@gmail.com] > Sent: Monday, July 15, 2013 12:59 AM > Subject: Re: [HOT] next HOT tech chat > > A very interesting topic, unfortunately 17.00 UTC equal 02.00 AM in > Indonesia. Here in Indonesia we're thinking of developing some kind > of cache server, since network bandwith is a major issue almost in > every workshop that we have.
So, there's a few different things you could cache. One is imagery/tiles. For tiles it's a well-solved problem, tile.osm.org uses a bunch of squid caches and the configuration is all at http://git.osm.org/chef.git/tree/HEAD:/cookbooks/tilecache Imagery is in principle the same, but you have to check the terms of use to make sure you can cache. In terms of bandwidth, tiles + imagery is probably most. The two remaining are API downloads and API uploads. For download, there's a few options. If you're using JOSM with the mirrored download plugin you can download from an XAPI-style mirror. This only works on map? calls (downloading an area), not the other API calls like download relation members. It also requires a plugin and an xapi-style mirror, which I'll get to later. There's almost-api which is a simple PHP script that directs to either an overpass API instance or the main API, as appropriate. It doesn't support oauth and some calls aren't properly supported. I'm working on a cgimap-based solution right now, which uses pgsnapshot as a backend. Better call support, and I have a config that redirects to the main API for calls it can't handle. All three problems require an xapi/pgsnapshot/overpass instance. This is roughly in the 500GB range. You could load an extract and use regional diffs, but I think these often lag behind by a few minutes+, and conflict resolution is a pain. As for API uploads, they can't be cached. For a deployment with limited resources, the only options are probably tiles + imagery caches. Hopefully if you can take away a significant part of the traffic it makes everything else better. For the Indonesia case, an API cache is an option, but I'd suggest the priority should be a tile CDN cache meeting the specs at http://wiki.openstreetmap.org/wiki/Servers/Tile_CDN. If someone wants to supply one, the contact info and requirements are on the wiki page. I know the admins have said a few times that they want a tile cache in Asia _______________________________________________ HOT mailing list HOT@openstreetmap.org http://lists.openstreetmap.org/listinfo/hot
