On Mon, May 11, 2009 at 5:44 PM, Stefan de Konink <[email protected]> wrote: > Matt Amos wrote: >> >> at a current mapping party everything works just fine. frederik has >> already explained how JOSM is going to deal with this and it doesn't >> need bbox locking on the DB. i assume richard is planning something >> similar for potlatch (?). > > I am still sure people would love to see XAPI requests to overcome the > current information overload. But that is typically clientside.
the problem with xapi-style requests is that people only see a subset of the data, making it much easier to enter duplicate information when people disagree about tagging. e.g: i load all the amenities in an area because i want to add an amenity=convenience_shop, but i won't see that someone has already added a shop=convenience. or i won't see anything that has been misspelt, e.g: maenity, sohp, whatever. >> bbox locking has its own problems, including easy DDOS, lack of >> concurrency, etc... but consider the mapping party example. if there >> is a way intersecting two editors' bboxes and they both lock their >> bboxes. now, neither of them can edit that way since it intersects the >> other's locked bbox. > > API 0.7 will of course implement partial ways too ;) Having the bbox as a > viewport. I don't see an easy way of DDOS unless you have a zillion of users > all locking *=*. Concurrency is perfectly possible, what you don't edit is > not locked (or if requested: hidden). of course 0.7 will have partial ways, be a zillion times faster and the moon on a stick. ;-) the (D)DOS comes from someone locking [*=*][-180,-90,90,180]. so you say, ok - lets let people only lock small areas, but then it just takes more accounts to perform the DOS. also, a "small" area in rural areas might be quite large in urban areas - can i continuously lock the central areas of large cities? maybe you say i can't lock for more than a certain period of time, but then i could script up something to continuously relock an area. ok, you say there's a back-off period where i can't relock, but then it just takes more accounts. ok, you say only whats edited is locked, but i can just lock all the elements. ok, you say there's a limit on how many things i can lock, but then it just takes more accounts. also, offline editing becomes almost impossible, as i can't hold the lock for long enough on many enough elements over the offline period. of course, optimistic locking also has DOS attacks (e.g: picking some ways and continuously incrementing the version numbers), but nothing is perfect ;-) finally, partial ways don't solve the problem of overlapping bboxes - sure, i can edit the geometry, but what if i change the tags? cheers, matt _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
