[OSM-dev] Filename extensions for OSM files
zerebubuth at gmail.com
Wed May 11 12:39:29 BST 2011
On Wed, May 11, 2011 at 12:23 PM, Peter Körner <osm-lists at mazdermind.de> 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
>> 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.
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