The essential thing of my proposal (however it be implemented) is that NOTHING changes with the current software or apps.
A standard request will just deliver the current state of the map. The API will filter out all "deleted" (just as now) and additionally all object that have a valid_per tag that evaluates to false (new). If you think about it, deleted just means: valid_per= false per today Then new apps could make use to request tot the API exact the time span as required. Send me all tracks valid on 2009 til 2021, because I want to map my town before the new quarter was put in place of the old one. JOSM might request "CURRENT + FUTURE" to let people edit future stuff. Editing deleted data could be enabled for the date of deletion only, we cannot delete data if we want to keep history. Just the data becomes invalid per deletion date. The date depends on the day someone finds a superfluous object, but may be changed if he knows the exact date it was removed. The bus routing planner might request all data valid on Monday morning between 9 and 12 so as the user is presented the right route the bus will take that morning. If next week the bus route will change, the relations describing a route can be edited in advance by editing new ones and enable them on a future date. Of course this is not manual editing anymore. it may be too complex to really keep the valid_per tag meaningful by editing by hand with 100K+ usrs. But in the future we will mass import many public databases, and they may be tagged accordingly on the date of import. The valid_per data needs not be implemented in OSM but can be retrieved from a separate "bus routing" database, where the OSM data just tell the user where to find "valid_per" data. I , just like Peter, do not see how problems in mixed data (the roman way) could get in the way, as nothing is deleted, just becomes invalid for standard application. Gert Gremmen ----------------------------------------------------- Openstreetmap.nl (alias: cetest) P Before printing, think about the environment. Van: talk-boun...@openstreetmap.org [mailto:talk-boun...@openstreetmap.org] Namens Peter Dörrie Verzonden: Monday, June 08, 2009 4:49 PM Aan: Frederik Ramm CC: talk@openstreetmap.org Onderwerp: Re: [OSM-talk] Wanted feature for API 0.7 ?? 2009/6/8 Frederik Ramm <frede...@remote.org> Hi, Peter Dörrie wrote: The current renderes wouldn't be able to handle it either and forcing 50+ applications to change would be unappropriate. Why, we're doing that all the time ;-) Yeah I thought so too, but this was one of the main arguments against my first try to establish something like this. There are many unsolved questions here. For example: What happens if parts of the "ancient" world transcend your "fourth dimension", e.g. a contemporary secondary road uses a few bits of an ancient Roman road. They would surely share the same nodes, wouldn't they? But if someone then deletes the secondary road (which he downloaded without ever knowing that the Roman road also exists because that was shielded from him), he must not delete the nodes because they are still used by other objects... My angle on this is primarily the historical-genetic one. Taking your example: 1. Brutus Mappus maps this roman long distance road in 100 B.C he tags it correctly with highway=roman and surface=cobblestone. The road is used in that form for the better part of the next two millennia. 2. In the 19th century it gets some heavy usage and deteriorates. The local government decides to build a new road, which uses some of the same vectors the roman road used so far. The grat-great-great (etc) son of Mappus (John Maps) splits the road, tagging part of it as highway=disused and others as highway=construction. 3. The new highway is ready and John tags it as highway=primary 4. The same thing happens several times over until fake Steve finds a motorway, using some parts of the primary road, using some parts of the roman road (which by now is not longer visible in the landscape and has been tagged as historic). Okay, what does this mean for whom? Users: The normal user will see a rendering which shows "what is on the ground". -> Motorway and those parts of the primary road that still exist Mappers: The normal mapper will see, what is relevant to him. -> Same as user and some additional tags (oneway, surface, maxspeed, etc.) plus perhaps those "disused" roads, as they may still be relevant to mapping. Special interest person (scientist, etc): He gets the possibility of seeing exactly what he wants to see. The situation in 100 B.C? no problem. Ask the database about all disused / historic / etc objects? also no problem. Different object sharing the same nodes over time (and changing them) is not a problem. Greetings, Peter
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