Java Client for publishing and consuming messages from Apache Kafka

I wanted to learn how to use Apache Kafka for publishing and consuming messages from Apache Kafka using Java client, so i followed these steps.

1. Download the Kafka binaries from Kafka download page
2. Unzip the kafka tar file by executing tar -xzf kafka_2.9.2-0.8.1.1.tgz. Then go to kafka directory by executing cd kafka_2.9.2-0.8.1.1
3. Next start the Zookeeper server by executing following command

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

4. Start the Kafka server by executing following command

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

5. Now your Zookeeper and Kafka server are ready and you can download the source code for sample project from here
6. This is how a Java Client that publishes messages to Kafka looks like, execute it couple of times to publish couple of messages First thing that you have to do while developing a producer is connect to the Kafka server, for that you will set value of metadata.broker.list property to point to the port on which kafka server is listening (You can find value of port and host name from server.properties that you used in step 4. Once you have Producer object you can use it for publishing messages by creating object of kafka.producer.KeyedMessage, you will have to pass name of the topic and message as argument
7. This is how the Java client for consumer of messages from Kafka looks like, run it and it will start a thread that will keep listening to messages on topic and every time there is a message it will print it to console The HelloKafkaConsumer class extends Thread class. In the constructor of this class first i am creating Properties class with value of zookeeper.connect property equal to the port on which zookeeper server is listening on. In the constructor i am creating object of kafka.javaapi.consumer.ConsumerConnector
   Once the ConsumerConnector is ready in the run() method i am passing it name of the topic on which i want to listen (You can pass multiple topic names here). Everytime there is a new message i am reading it and printing it to console.