Apache Kafka integration for Apache Jackrabbit Oak.

This is a prove of concept implementation of an Oak Observer sending all changes to a Oak repository to a Kafka message log.

To get started with Oak Kafka, build the latest sources with Maven 3 and Java 6 (or higher):

mvn clean install

Then start a local Kafka server. Change into the Kafka installation directory and start a Zookeeper instance and then the Kafka server:

bin/zookeeper-server-start.sh config/zookeeper.properties
bin/kafka-server-start.sh config/server.properties

To see the output of the test you need to attach a message consumer to Kafka:

./bin/kafka-console-consumer.sh --zookeeper localhost:2181 --blacklist \
none --property print.key=true

Now running KafkaObserverTest.main should dump the changes to the console:

commit	CommitInfo{sessionId=session-6, userId=admin, date=1404470600166, info={}}
NODE_CHANGED	/
PROPERTY_ADDED	/new node 1404470600164/jcr:primaryType
NODE_ADDED	/new node 1404470600164
NODE_CHANGED	/oak:index
NODE_CHANGED	/oak:index/nodetype

Through KafkaObserverService Oak Kafka can be run inside an OSGi environment (e.g. Apache Sling). Note that due to OAK-1950 Oak Kafka currently has a dependency on oak-core:1.1-SNAPSHOT.