kafka-exercise-Using-Custom-Partitioner.md

Exercise: Using Custom Partitioner

Write a new Kafka application PartitionerDemo (using Kafka Producer API) as follows:

1. Write a custom Partitioner
   1. Implement Partitioner interface
   2. Review Cluster (which is one of the input arguments of Partitioner.partition method)
   3. Decide what to do when requested for a partition ID in partition method
2. Write a KafkaProducer
   1. Register the custom Partitioner using ProducerConfig.PARTITIONER_CLASS_CONFIG property
   2. Use a Callback input object (to Producer.send) and display the partition ID
3. Create a topic with 2 partitions (on a single Kafka broker)
   1. Hint: Use as many kafka-console-consumer as many partitions are in use
   2. Use kafka-console-consumer with --property print.key=true to print keys
4. Execute the application and the following tests. Observe the behaviour.
   1. Define the partition key in Producer.send
   2. Don't specify the partition key
5. (EXTRA) Use kafka-topics --alter to increase the number of partitions and observe how Cluster reflects the change
   1. ./bin/kafka-topics.sh --zookeeper :2181 --alter --topic PartitionerDemo-input --partitions 3

Duration: 30 mins