Kafka integration basics in Spring Boot - Mini Project: Build & Apply

Kafka integration basics

📖 Scenario: You are building a simple Spring Boot application that sends and receives messages using Kafka. This is like sending letters through a post office and then reading them when they arrive.

🎯 Goal: Create a Spring Boot application that sets up a Kafka topic, sends a message to it, and listens for messages from that topic.

📋 What You'll Learn

Create a Kafka topic configuration bean

Create a Kafka producer bean to send messages

Create a Kafka consumer bean to listen for messages

Send a test message to the Kafka topic

💡 Why This Matters

🌍 Real World

Kafka is used in many applications to send messages between different parts of a system reliably and quickly, like sending notifications or processing orders.

💼 Career

Understanding Kafka integration with Spring Boot is valuable for backend developers working on scalable, event-driven systems.

1

Create Kafka topic configuration

Create a Spring bean method called topic that returns a NewTopic object with the name "myTopic", 1 partition, and 1 replica.

Spring Boot

# Create a Spring bean method called topic that returns a NewTopic with name "myTopic", 1 partition, and 1 replica
# Your code here

Need a hint?

Use @Bean annotation and return new NewTopic("myTopic", 1, (short) 1).

2

Create Kafka producer bean

Add a Spring bean method called kafkaTemplate that returns a KafkaTemplate<String, String> using a ProducerFactory<String, String> parameter named producerFactory.

Spring Boot

import org.apache.kafka.clients.admin.NewTopic;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.core.ProducerFactory;

@Configuration
public class KafkaTopicConfig {

    @Bean
    public NewTopic topic() {
        return new NewTopic("myTopic", 1, (short) 1);
    }

    // Create kafkaTemplate bean here
    // Your code here
}

Need a hint?

Define a @Bean method named kafkaTemplate that takes ProducerFactory<String, String> and returns new KafkaTemplate<>(producerFactory).

3

Create Kafka consumer listener

Create a Spring component class called KafkaConsumer with a method listen annotated with @KafkaListener(topics = "myTopic") that takes a String message parameter.

Spring Boot

import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

@Component
public class KafkaConsumer {

    // Create listen method with @KafkaListener for topic "myTopic"
    // Your code here
}

Need a hint?

Use @Component on the class and @KafkaListener(topics = "myTopic") on the method that takes a String message.

4

Send a test message to Kafka topic

In a Spring @Component class called KafkaSender, create a method sendMessage that takes a KafkaTemplate<String, String> named kafkaTemplate and sends the message "Hello Kafka" to the topic "myTopic" using kafkaTemplate.send("myTopic", "Hello Kafka").

Spring Boot

import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Component;

@Component
public class KafkaSender {

    // Create sendMessage method that sends "Hello Kafka" to "myTopic"
    // Your code here
}

Need a hint?

Define a @Component class with a method sendMessage that calls kafkaTemplate.send("myTopic", "Hello Kafka").