On Wed, May 11, 2011 at 12:23 PM, Peter Körner <[email protected]> wrote: > Am 11.05.2011 13:17, schrieb Matt Amos: >>> >>> We should probably introduce an attribute on the<osm> tag that says that >>> this is a history file. Just as we are currently discussing for the PBF >>> version. >> >> while we're at it, let's have a flag to indicate if the elements are >> sorted by ID, how many prime-numbered elements there are, whether >> there was a full moon when it was generated and what the colour of the >> file is. i'm up for all of that as long as it's blue. > > history files have similar syntax as normal osm files, but very different > semantics. A program processing a history file needs to be aware or it > - having multiple objects with the same id > - having objects that stop being existent in some point in time > - that have an extra information attached > > that way it is useful for a program to know, if a file fed into it via stdin > will be processed fine right from the start. nobody likes processes that > fail after 10 hours because of a missing --this-is-an-history-file flag.
it'll be far less than 10 hours before the first element with visible="false" or multiple versions comes through. in fact, i bet it'd happen within the first 10 lines. all OSM files are potentially history files (e.g: http://osm.org/api/0.6/node/1/history) - they all have the visible and version attributes on all elements, despite that not being needed for dealing with a snapshot. some programs may make assumptions about the contents of OSM files, but that's for the program in question to assert, and for the user to be aware of. cheers, matt _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
