[OSM-dev] New Replication Functionality

Brett Henderson brett at bretth.com
Tue May 27 00:47:15 BST 2008

I stuff3d up the 0.27 release.  0.28 is up now and fixes a major runtime 
problem preventing it from ever launching.

Brett Henderson wrote:
> Hi All,
> I've just released osmosis 0.27 which adds some additional support for 
> downloading and applying changesets from the planet server.
> As you may or not be aware there are currently three changesets 
> available on the planet server.  These are the daily, hourly and 
> minute changesets.
> I have added two new tasks to osmosis for consuming these files.  
> These are:
> --read-change-interval - This provides the ability to download a set 
> of changes, merge them into a single changeset and pass the data to 
> the next task in the pipeline.  It maintains a working directory where 
> it stores its configuration file and tracks the latest downloaded 
> timestamp.
> --read-change-interval-init - This is necessary to initialise the 
> working directory used by the --read-change-interval task.
> I'll illustrate using an (untested) example.  This example will keep 
> an xml file containing a small bounding box up-to-date.
> 1. Create the working directory with a timestamp initialised to the 
> start of today.
> $ osmosis --read-change-interval-init "myworkingdirectory" 
> "2008-05-26_00:00:00"
> 2. Edit the config file.
> The configuration file will contain suitable defaults for downloading 
> the hourly changes and hopefully won't require any modifications.
> 3. Extract an extra of the world that you're interested in using a 
> planet that is newer than the start of today (the original source must 
> contain later data than you initialise the initial timestamp to).
> osmosis --rx planet.osm.bz2 --bb left=0 top=10 right=10 bottom=0 --wx 
> myextract.osm
> 4. Apply the latest changes to the extract, produce an updated extract 
> and rename new file the old name.
> osmosis --read-change-interval "myworkingdirectory" --rx myextract.osm 
> --ac --bb left=0 top=10 right=10 bottom=0 --wx myextract-updated.osm
> mv myextract-updated.osm myextract.osm (Note that the error code 
> returned by osmosis should be checked in the previous step)
> Some limitations exist:
> Currently only the hourly and minute changesets are supported due to 
> the bzip2 encoding used by the daily changesets.  I should fix this 
> soon but it will take a little bit of rework in the task design, it's 
> currently hard coding a gzip encoding.
> There is no limits to the number of files downloaded, I should add a 
> configuration option to limit the number of files (and subsequent 
> processing threads) processed in a single invocation.
> I hope people find it useful.  Any feedback appreciated.
> Cheers,
> Brett

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