Using Spring Boot with Apache Pulsar for Event Streaming

As applications evolve into microservices architectures, the need for efficient event streaming systems becomes crucial. Apache Pulsar is a cloud-native, distributed messaging and streaming platform capable of handling high throughput and low latency communication. In this post, we’ll explore how to integrate Apache Pulsar with Spring Boot to build an event-driven architecture.

What is Apache Pulsar?

Apache Pulsar is a highly scalable and versatile event streaming platform that offers a unified solution for both queuing and streaming applications. Some of its key features include:

• Multi-Tenancy: Supports multiple independent tenants managing their subscriptions and namespaces.
• Geo-Replication: Built-in support for geo-replicating messages across clusters.
• Low Latency: Designed for low-latency message delivery, capable of handling large amounts of data.

Setting Up Apache Pulsar with Spring Boot

Let’s create a Spring Boot application that integrates with Apache Pulsar to handle event streaming.

1. Set Up a Pulsar Instance

To get started, you need to have an Apache Pulsar instance running. You can run Pulsar locally using the following commands:

bin/pulsar standalone

This command starts a standalone Pulsar instance with a broker, a bookie, and a zookeeper.

2. Creating a Spring Boot Project

Create a new Spring Boot project using Spring Initializr. In addition, include the following dependency for Pulsar:

<dependency>
    <groupId>org.apache.pulsar</groupId>
    <artifactId>pulsar-client</artifactId>
    <version>2.9.0</version>
</dependency>

Creating a Producer to Send Messages

Next, you will set up a message producer that will send messages to a Pulsar topic:

import org.apache.pulsar.client.api.*;
import org.springframework.stereotype.Service;

@Service
public class PulsarProducer {
    private final Producer<String> producer;

    public PulsarProducer() throws PulsarClientException {
        PulsarClient client = PulsarClient.builder()
                .serviceUrl("pulsar://localhost:6650")
                .build();
        this.producer = client.newProducer(Schema.STRING)
                .topic("my-topic")
                .create();
    }

    public void sendMessage(String message) throws PulsarClientException {
        producer.send(message);
        System.out.println("Sent message: " + message);
    }
}

Creating a Consumer to Listen for Messages

Next, create a consumer to listen for messages from that topic:

import org.apache.pulsar.client.api.*;
import org.springframework.stereotype.Service;

@Service
public class PulsarConsumer {
    public PulsarConsumer() throws PulsarClientException {
        PulsarClient client = PulsarClient.builder()
                .serviceUrl("pulsar://localhost:6650")
                .build();
        Consumer<String> consumer = client.newConsumer(Schema.STRING)
                .topic("my-topic")
                .subscriptionName("my-subscription")
                .subscribe();

        while (true) {
            // Wait for a message
            Message<String> msg = consumer.receive();
            System.out.printf("Received message: %s%n", msg.getValue());
            consumer.acknowledge(msg);
        }
    }
}

Creating REST Endpoints for Interaction

To demonstrate integration, create a REST controller to send and receive messages:

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/api/messages")
public class MessageController {

    @Autowired
    private PulsarProducer pulsarProducer;

    @PostMapping
    public void sendMessage(@RequestBody String message) throws PulsarClientException {
        pulsarProducer.sendMessage(message);
    }
}

Running Your Application

Run your Spring Boot application and use Postman to send test messages to your API:

curl -X POST http://localhost:8080/api/messages -d "Hello, Pulsar!"

Conclusion

Integrating Apache Pulsar with Spring Boot provides a powerful framework for implementing real-time data processing and event-driven architecture. By harnessing the capabilities of Pulsar, you can build scalable applications that handle a high volume of messages efficiently.

For more detailed insights into working with Spring Boot and Pulsar, and for learning about advanced messaging patterns, explore the wide array of resources available at ITER Academy.

To learn more about ITER Academy, visit our website.