On Tue, Oct 13, 2009 at 12:19:34AM +0200, Tomáš Kouba wrote: > Hello, > > I have an idea how to dramatically fasten building a map in JOSM. > Currently if you want to update your maps via JOSM then it has to download > the whole map every time which is very slow. So it would be great if JOSM > would download only diferrences in map. > > Suggested solution: > Create a "cacher" (sort of proxy server) probably located on localhost, > which would store and cache your maps. Cacher would stand between JOSM and > map server API (see http://files.chciwww.cz/OSM_Components.png). You could > use caching feature just by specifying this "cache server" as a map server > in JOSM. Cacher would have its own map database and if you wanted cacher > to get you a map up-to-date, cacher would download from main map server > only differences in map. > How come this feature isn't already implemented as it looks so important? > Or is there a some sort of "tack", that kills attemps to cache maps? > I'm new to Open Street Map project so my apologies if I'm missing > something. Reason for my contribution is that I'm looking for a subject of > my bachelor's thesis and this looks useful.
How does the cache know when to invalidate individual objects from its cache? This is a non trivial problem with squid and other simple object caches and those simply fall-back to a If-Modified-Since query for an individual object. A map call which josm uses to download map data is a multi-objects-in-an-area call which would when fall-back to an if-modified-since query need to do the very same query to the database - So - you would not save time in the database but only on transfer ... Flo -- Florian Lohoff f...@rfc822.org "Es ist ein grobes Missverständnis und eine Fehlwahrnehmung, dem Staat im Internet Zensur- und Überwachungsabsichten zu unterstellen." - - Bundesminister Dr. Wolfgang Schäuble -- 10. Juli in Berlin
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