osm-watch

Advanced watching of OpenStreetMap changes

Installation

Pre-requisites:

Java SDK
Ant
Servlet container (Tomcat 7.0 for example)

Get the code and build

% git clone https://github.com/cstenac/osm-watch
% cd osm-watch
% ant

The default ant target fetches ivy, fetches the dependencies, compiles the code and creates dist/osm-watch.war

Create the configuration file

Create in the home folder of the user running tomcat a file called osm-watch.properties, with the following content:

baseurl=http://localhost:8080/osm-watch
dialect=HIBERNATE DIALECT CLASS
driver=JDBC driver class
jdbcurl=JDBC connection string

For example, to use an embedded SQLite database (good for development), use:

dialect=com.applerao.hibernatesqlite.dialect.SQLiteDialect
driver=org.sqlite.JDBC
jdbcurl=jdbc:sqlite:/tmp/alert.db

To use PostgreSQL:

dialect=org.hibernate.dialect.PostgreSQLDialect
driver=org.postgresql.driver
jdbcurl=jdbc:postgresql:dbname

"baseurl" must be the URL of your instance. It is used by the OAuth authentication.

Install and run

Copy dist/osm-watch.war in the webapps/ folder of your Tomcat
Start it ! ./bin/catalina.sh start
Go to http://localhost:8080/osm-watch/

To process the updates, you need to access the following URL: http://localhost:8080/osm-watch/debug/next_augmented_diff

It is recommended to create in the db and index on changeset(username)

TODO: explain how to load the previous changesets

Design

Features

Watching

Watch a bounding-box, get notified for changes that are truly within the bbox, not overlap
Watch an admin relation, get notified within
Watch a tag (within a bbox ?), get notified when
- NWR with the tag is modified
- Tag is added on a NWR
- Tag is removed from a NWR
- NWR with the tag is deleted
Watch an OSM user, get notified whenever he/she makes a commit

Notifications

Options:

Get notified only if first matching edit by a given contributor
Real-time / Scheduled
Generated RSS feed

Implementation

In order to provide the "tag is removed from a NWR" feature, it builds on the augmented diffs from overpass: http://overpass-api.de/augmented_diffs/

The OSC files are fetched, and processed:

The geometry of ways is reconstructed
The really deleted objects are identified and segregated
For modified objects, a previous/new version is created
Aggregated modifications are sent to the matchers

This backend is in Java, and is API only. A frontend TBD exists to set up the alerts

Third party code

OSM-Watch embeds some code from the JOSM project for the filtering part. The JOSM code is Copyright 2007 by Immanuel Scholz and others, Copyright 2008 by Petr Nejedly, and is used according to the terms of the GPL license

cstenac / osm-watch