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Implementing a Kafka Producer and Consumer using Spring Cloud Stream

Apache Kafka is a distributed streaming platform that can be used to publish, subscribe to, store, and process streams of records in real time. Spring Cloud Stream is a framework that makes it easy to build applications that use Kafka. It provides a high-level abstraction over Kafka, making it easier to develop and deploy streaming applications.

This article will show you how to implement a Kafka producer and consumer using Spring Cloud Stream.

Prerequisites

  • You will need to have Java 8 or higher installed on your machine.
  • You will also need to have Apache Kafka installed and running.
  • Finally, you will need to have Spring Boot installed and running.

Creating a Kafka Producer

To create a Kafka producer using Spring Cloud Stream, you need to create a Spring Boot application and add the following dependencies:

XML
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-stream-binder-kafka</artifactId>
</dependency>

Once you have added the dependencies, you need to create a Kafka producer bean. You can do this by annotating a method with the @KafkaListener annotation. The @KafkaListener annotation tells Spring Cloud Stream to listen for messages on the specified topic.

The following code shows an example of a Kafka producer bean:

Java
@KafkaListener(topics = "my-topic")
public void produce(String message) {
    // Produce the message to Kafka
    System.out.println("Producing message: " + message);

Creating a Kafka Consumer

To create a Kafka consumer using Spring Cloud Stream, you need to create a Spring Boot application and add the following dependencies:

XML
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-stream-binder-kafka</artifactId>
</dependency>

Once you have added the dependencies, you need to create a Kafka consumer bean. You can do this by annotating a method with the @KafkaListener annotation. The @KafkaListener annotation tells Spring Cloud Stream to listen for messages on the specified topic.

The following code shows an example of a Kafka consumer bean:

Java
@KafkaListener(topics = "my-topic")
public void consume(String message) {
    // Consume the message from Kafka
    System.out.println("Consuming message: " + message);

Starting the Producer and Consumer

Once you have created the producer and consumer beans, you can start the applications.

To start the producer application, run the following command:

mvn spring-boot:run

To start the consumer application, run the following command:

mvn spring-boot:run

Sending and Receiving Messages

Once the producer and consumer applications are running, you can send and receive messages.

To send a message, simply call the produce() method on the producer bean. The following code shows an example of how to send a message:

Java
// Get the producer bean
Producer producer = context.getBean(Producer.class);

// Send a message
producer.produce("Hello, world!");

To receive a message, simply call the consume() method on the consumer bean. The following code shows an example of how to receive a message:

Java
// Get the consumer bean
Consumer consumer = context.getBean(Consumer.class);

// Consume a message
consumer.consume();

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Kafka producer and consumer
Spring Boot application
Kafka topic

Conclusion

Spring Cloud Stream makes it easy to implement Kafka producers and consumers in Spring Boot applications. By using Spring Cloud Stream, you can avoid the complexity of dealing with Kafka directly.

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