How does Kafka obtain the results from consumers?

2 years ago
William Carter
1 minute

Consumers in Kafka can retrieve results by fetching records. Here are the steps for obtaining Kafka consumer results using the Java API:

  1. Create Kafka consumer configuration.
Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("group.id", "my-consumer-group");
props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
  1. Create an instance of a Kafka consumer.
KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
  1. Subscribe to topics that interest you.
consumer.subscribe(Collections.singletonList("my-topic"));
  1. Retrieve records in a loop.
while (true) {
    ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
    for (ConsumerRecord<String, String> record : records) {
        System.out.println("Received record: " + record.value());
    }
}

In the above code, the poll() method is used to retrieve records, with a parameter for the maximum wait time. The ConsumerRecords object contains a batch of consumed records, which you can access by iterating through each ConsumerRecord object.

Please note that the sample code provided is a simplified version. In actual use, more configurations and processing logic may be required.

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