Apache Pulsar: A Comprehensive Guide

Apache Pulsar is a distributed messaging system designed to handle real-time data streams. It supports both messaging and streaming use cases, making it a versatile choice for organizations looking to build scalable applications.

Pulsar's architecture is based on a flexible messaging model that separates the storage and serving layers. This provides significant advantages in scalability and performance.

            graph TD;
                A[Clients] -->|Produce/Consume| B[Pulsar Brokers];
                B --> C[Pulsar Storage];
                C --> D[BookKeeper];
                B --> E[Metadata Store];
        

Topics

Topics are the categories or feeds through which messages are published.

Subscriptions

Subscriptions allow consumers to receive messages from topics in various modes (Exclusive, Shared, Failover, etc.).

Producers and Consumers

Producers send messages to topics, while consumers read messages from subscriptions.

Step-by-Step Installation

1. Download Pulsar from the official website.
2. Extract the downloaded package.
3. Start Pulsar in standalone mode using the command:

   bin/pulsar standalone

4. Access the Pulsar admin dashboard at http://localhost:8080.

Producer Example

            import org.apache.pulsar.client.api.*;

            PulsarClient client = PulsarClient.builder()
                .serviceUrl("pulsar://localhost:6650")
                .build();

            Producer producer = client.newProducer()
                .topic("my-topic")
                .create();

            producer.send("Hello Pulsar!".getBytes());
            producer.close();
            client.close();
        

Consumer Example

            Consumer consumer = client.newConsumer()
                .topic("my-topic")
                .subscriptionName("my-subscription")
                .subscribe();

            Message msg = consumer.receive();
            System.out.println("Received message: " + new String(msg.getData()));
            consumer.acknowledge(msg);
        

• Monitor your Pulsar cluster regularly to ensure optimal performance.
• Use appropriate subscription types based on your use case.
• Implement message deduplication if necessary.
• Scale your brokers and storage independently as needed.