Category: Kafka Fundamentals l

bookmark_borderThe Kafka Java APIs

Posted on by Jay Jo

Kafka provides a series of Application Programming Interfaces (APIs). These make it easier to write applications that use Kafka.

Kafka maintains a set of client libraries for Java, although there are open-source projects providing similar support to a variety of other languages.

Include these client libraries in your application to easily interact with Kafka!

  • Producer API: This allows you to build producers that publish messages to Kafka
  • Consumer API: This allows you to build consumers that read Kafka messages.
  • Streams API: This allows you to read from input topics, transform data, and output it to output topics
  • Connect API: This allows you to build custom connectors, which pull from or push to specific external systems.
  • AdminClient API: This allows you to manage and inspect higher-level objects like topics and brokers.

Producer data to Kafka

package kafka.client;

import org.apache.kafka.clients.producer.*;
import java.util.Properties;

public class Main {
    public static void main(String[] args) {
        Properties props = new Properties();

        props.put("bootstrap.servers", "localhost:9092");
        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        Producer<String, String> producer = new KafkaProducer<>(props);
        for (int i = 0; i < 100; i++) {
            producer.send(new ProducerRecord<String, String>("count-topic", "count", Integer.toString(i)));
        }
        producer.close();
    }
}
dependencies {
    implementation 'org.apache.kafka:kafka-clients:2.2.1'
    testImplementation 'junit:junit:4.12'
}
  • dependencies

Execute

./gradlew run
kafka-console-consumer --bootstrap-server localhost:9092 --topic count-topic --from-beginning

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