Hello, -------- Original-Nachricht -------- > From: "Bruce Skingle" <[email protected]> > Subject: [OSM-dev] OSM Map Browser Application
> I've been working on a map browser project, and I have some code I'm > ready to think about releasing (free, with source, under the Eclipse > Public Licence). > > It can call the OSM API to download the XML data for the viewable > portion of a raster map and display the OSM data as an overlay, which > seems fine. > > My main issue is with the interactive map which renders on the fly from > the XML API. It requests "tiles" of XML data, equivalent to Slippy map > tiles at zoom level 12 (in terms of area covered). The calls to the API > are rather slow, which suggests to me that the server is working hard > to answer the queries, and I want to get some people who understand > what's happening on the server to look at it before I release to a > wider audience, hence this email. > > > > The program caches all data and never re-requests anything it has cached Caching is very useful to save download time and especially server load. > OSM provides ready cut "tiles" of XML data, this seems like a sensible > approach to me, but I might be alone. I've heard about something called > TRAPI but haven't seen much information about it. TRAPI would be the answer to get osm data without server load on the main osm server. For implementations look at: http://wiki.openstreetmap.org/wiki/Tile_data_server If one user make a higher load on the main osm server, it will be banned. > I take the planet file and produce these tiles. > > I take the planet file and produce Eclipse plugins so users can > download, say, a countries worth of data. This makes it more useful > as an offline tool. Maybe it's better to produce tile data files in osm-Format - the same as the input. Then it is useful for more applications - like my osm3d. The idea is really simple: just parse the XML planet file with a SAX parser (you can't load Gigabytes of XML data into memory), save the node id's for nodes with lat/lon inside your tile, and find all ways and relations using these nodes and all relations using the ways selected before. That is faster than loading the planet to a database and using sql to select the ways/node/relation. But if you want to produce tile data files for the whole planet - then a database may be faster (just parsing one time and the rest is done by the database). A server, where you can download tile data files will always be faster than TRAPI , but not so flexible. Maybe you can provide such tool as a jar file usable without Eclipse? > Regards, > Bruce Skingle. Stefan Ziegler. -- Diplom-Informatiker, Homepage: http://www.stefanziegler-online.de/ Wir alle wissen mehr als das, wovon wir wissen, dass wir es wissen. (Thornton Wilder) Preisknaller: GMX DSL Flatrate für nur 16,99 Euro/mtl.! http://portal.gmx.net/de/go/dsl02 _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
