[OSM-dev] OsmChange format and 0.6

Matt Amos zerebubuth at gmail.com
Sun Feb 15 22:32:48 GMT 2009


On Sun, Feb 15, 2009 at 11:22 AM, Brett Henderson <brett at bretth.com> wrote:
> The problem has many parallels to source code management as you've pointed
> out.  Using subversion as a guide may be helpful. (SNIP) From
> what I can remember, ClearCase MultiSite uses branches with ownership locks
> to prevent concurrent edits.  (SNIP) The other team goes through a similar
> process to see your changes. Without thinking this too far through, it might be
> possible to do something similar in OSM.

this sounds like a lot of work :-)

> The merge would always require
> manual intervention, but if the local region of interest is small it may be
> manageable.  Anyway, that's about as far as I've gotten.  It's firmly in the
> too-hard basket the moment, the more I think about it the harder it seems
> :-)

we could reduce the occurrence of conflicts by considering more
fine-grained diffs. darcs' "patch theory" can be ransacked for good
ideas (http://wiki.darcs.net/DarcsWiki/WhyYouWantPatchTheory), for
example: if i change the location of a node and independently someone
changes or adds a tag, the two operations can be reordered without
interfering with eachother and therefore do not need manual
intervention to resolve.

it gets more complicated with way nodes and relation members, due to
the ordering, but i think its within the bounds of possibility.

of course, there are things that no replication / patching scheme can
fix, such as two people adding the same node in roughly the same place
with roughly the same tags... but the benefits of this sort of method
for distributed editing could seriously help people in areas of poor
or intermittent connection quality.

cheers,

matt




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