Table of Contents

1. Challenge

   Clone the Starter Project from GitHub and Perform a Test Run

   1. Clone the starter project from GitHub.

   cd ~/
   git clone https://github.com/linuxacademy/content-ccdak-kafka-simple-consumer.git
   

   1. Perform a test to make sure the code is able to compile and run.

   cd content-ccdak-kafka-simple-consumer/
   ./gradlew run
   

   The output should contain the message printed by the Main class: Hello, world!.

2. Challenge

   Implement a Consumer in the Main Class and Run It

   1. Add the Kafka Client Libraries as a project dependency in build.gradle with:

   vi build.gradle
   

   1. In the dependencies { ... } block, add the following line:

   implementation 'org.apache.kafka:kafka-clients:2.2.1'
   

   1. Edit the Main class:

   vi src/main/java/com/linuxacademy/ccdak/kafkaSimpleConsumer/Main.java
   

   1. Implement a basic consumer that consumes messages from the topic and prints them to the screen:

   package com.linuxacademy.ccdak.kafkaSimpleConsumer;
   
   import org.apache.kafka.clients.consumer.*;
   import java.util.Properties;
   import java.util.Arrays;
   import java.time.Duration;
   
   public class Main {
   
       public static void main(String[] args) {
           Properties props = new Properties();
           props.setProperty("bootstrap.servers", "localhost:9092");
           props.setProperty("group.id", "my-group");
           props.setProperty("enable.auto.commit", "true");
           props.setProperty("auto.commit.interval.ms", "1000");
           props.setProperty("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
           props.setProperty("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
           KafkaConsumer<String, String> consumer = new KafkaConsumer<String, String>(props);
           consumer.subscribe(Arrays.asList("inventory_purchases"));
           while (true) {
               ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
               for (ConsumerRecord<String, String> record : records) {
                   System.out.printf("offset = %d, key = %s, value = %s%n", record.offset(), record.key(), record.value());
               }
           }
       }
   
   }
   

   1. Run the code:

   ./gradlew run
   

   The program should print a series of messages from the Kafka topic containing information about item purchases.