Change monitoring
From OpenStreetMap
As in any wiki-like system, it is important in OpenStreetMap to be able to monitor how the data has changed over time (i.e. view history information) and to be able to roll back to an earlier version where necessary.
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What's available at the moment?
There's an experimental node watch capability in Osmxapi. This provides an RSS feed of changes to any node that has been tagged with a watch tag (eg watch:SteveC=yes). There's some clever shit which prevents a malicious user from disabling or modifying another user's watch list by messing with their tags.
Potlatch shows you the editing history of a particular way when you select it and press 'H'. It also allow you fetch an older version
The Protocol supports a call to fetch history information. See OSM Protocol Version 0.5#Retrieving Object History
JOSM's history panel will show you the name of the last user who edited an object when you select it. You can also see this by zooming in on the Osmarender tiles@home layer of the map.
Another angle on the problem is to look at historical data found in older planet.osm downloads. These don't include user/timestamp information, but we do provide a snapshot (now including diffs every minute!) You can, if you know how, use these to build up a picture of changes over time. Obviously working with planets and diffs requires technical skills, and some memory/cpu intensive processing, but there are some more user friendly progress animation tools, which are essentially built on top of this (link?)
Future ideas/brain storming for this feature
Changesets and Reverts details an idea to group edits into "changesets" at the API level, which would impact approaches to introducing monitoring, potentially making any monitoring display more meaningful, since it introduces user comments and reduces the number of events.
