Hi Frederick, Answers below. Oleg Shaniuk is the CM developer who presented about Mapzen POI Collector at SOTM - he'll be able to give more detail than me.
On Fri, Dec 4, 2009 at 12:28 AM, Frederik Ramm <frede...@remote.org> wrote: > Nick, > > Nick Black wrote: >> >> Mapzen POI Collector is a free iPhone app that makes it really easy to >> collect POIs for OpenStreetMap. Users locate themselves using the >> iPhone's built in GPS, position a pin at the location of the POI they >> want to add and then choose from a range of pre-selected categories. > > I'm lacking an iPhone myself so excuse me if my questions are stupid. I'm > interested in hearing about some technology aspects behind the POI collector > (unless these are terribly secret). There are no stupid questions - only stupid people who don't ask questions :-) > > I assume that the POI collector not only lets you collect new POIs but also > modify existing ones. For this, the existing ones must be shown as active > elements on the map that the device displays. Given that the OSM server > proper is too slow to answer real-time "give me POIs in my vicinity" > queries, and given that XAPI is not generally reliable for anything > commercial grade, I assume that you are using your own XAPI-like POI > database which tracks changes from the main OSM server and feeds them to the > iPhone users, is that correct? Mapzen POI Collector talks to the live OSM server - both to read and write. We looked at created a XAPI like server, but the for the first versions of all of the Mapzen tools we decided it was not worth it. The server is actually quite responsive for POIs - maybe its because node queries are faster than way queries and because the bboxes are generally very small (equal to a few tiles). The fact that everything is slow due to network latency and the general slowness of 3G networks in EU + US has a perverse effect of the user experience in that both the tiles and POIs load slowly, lessening the impact of slow loading POIs. The Mapzen Editor (mapzen.cloudmade.com) is another matter. The data can load very slowly - its a common user complaint. Going forward we'll want to speed up loading data into the Mapzen editor a lot. We have some ideas about how to do this on the client side (happy to share if anyone is interested), but the bottleneck is going to be the server. Having a XAPI like server would let us split requests for different layers and generally speed things up. It does raise issues around conflicts though. An alternative is to speed up the main OSM server - this is good because then everyone in the community benefits (eg Potlatch and other editor users) and mainly because it reduces issues around conflicts. If we ended up doing a CM XAPI, we'd open up access to anyone who wanted to use it anyway, so other editors and mappers could benefit. > > Are you simply getting a feed that is close to real-time as possible and > then let the device send updates directly to the OSM server, and what do you > do in the hopefully rare case of an editing conflict? As we're reading from and writing to live OSM, conflicts are rare. It would be pretty cool to be standing outside a shop, adding it as a POI with Mapzen, only to discover an OSMer standing next to you, adding the same shop with Vespucci. Its going to happen sooner or later... -- Nick Black twitter.com/nick_b _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
