disco-java-ext is a Java implementation of the Disco external interface (http://discoproject.org/doc/external.html). I attempted to mimic the Python interface for map and reduce functions in the MapFunction and ReduceFunction abstract classes.

Running wordcount:

1. Git the source
2. Run "ant" to build the jar. Sun Java 1.6 is the only dependency.
3. Distribute the jar to all the nodes in your cluster. I prefer to use NFS or DFS, either way the path needs to be the same on all nodes.
4. Modify java_map.sh and java_reduce.sh so that OS_DISCO is the path to the jar you just distributed.
5. Modify RunDiscoJavaExt.py to point to your Disco master
6. Run "python RunDiscoJavaExt.py"

Running a custom map/reduce:

1. Do steps 1-5 above to get a working wordcount
2. Implement your own rmaus.disco.external.MapFunction and ReduceFunction
3. Jar your map/reduce functions and distribute them to the nodes (similar to #3 above)
4. Modify java_map.sh and java_reduce.sh so your launch classpath includes your custom map/reduce jar.
5. Modify RunDiscoJavaExt.py vars "map_class" and "reduce_class" to point to your custom map/reduce classes (instead of the wordcount classes)
6. Run "python runDiscoJavaExt.py"