deb-sahara/etc/edp-examples/edp-java/README.rst

EDP WordCount Example

Overview

WordCount.java is a modified version of the WordCount example bundled with version 1.2.1 of Apache Hadoop. It has been extended for use from a java action in an Oozie workflow. The modification below allows any configuration values from the <configuration> tag in an Oozie workflow to be set in the Configuration object:

// This will add properties from the <configuration> tag specified
// in the Oozie workflow.  For java actions, Oozie writes the
// configuration values to a file pointed to by ooze.action.conf.xml
conf.addResource(new Path("file:///",
                          System.getProperty("oozie.action.conf.xml")));

In the example workflow, we use the <configuration> tag to specify user and password configuration values for accessing swift objects.

Compiling

To build the jar, add hadoop-core and commons-cli to the classpath.

On a node running Ubuntu 13.04 with hadoop 1.2.1 the following commands will compile WordCount.java from within the src directory:

$ mkdir wordcount_classes
$ javac -classpath /usr/share/hadoop/hadoop-core-1.2.1.jar:/usr/share/hadoop/lib/commons-cli-1.2.jar -d wordcount_classes WordCount.java
$ jar -cvf edp-java.jar -C wordcount_classes/ .

Note, on a node with hadoop 2.3.0 the javac command above can be replaced with:

$ javac -classpath /opt/hadoop-2.3.0/share/hadoop/common/hadoop-common-2.3.0.jar:/opt/hadoop-2.3.0/share/hadoop/mapreduce/hadoop-mapreduce-client-core-2.3.0.jar:/opt/hadoop-2.3.0/share/hadoop/common/lib/commons-cli-1.2.jar:/opt/hadoop-2.3.0/share/hadoop/mapreduce/lib/hadoop-annotations-2.3.0.jar -d wordcount_classes WordCount.java

Running from the Sahara UI

Running the WordCount example from the sahara UI is very similar to running a Pig, Hive, or MapReduce job.

1. Create a job binary that points to the edp-java.jar file

2. Create a Java job type and add the job binary to the libs value

3. Launch the job:

   1. Add the input and output paths to args
   2. If swift input or output paths are used, set the fs.swift.service.sahara.username and fs.swift.service.sahara.password configuration values
   3. The Sahara UI will prompt for the required main_class value and the optional java_opts value