What it does
Apache Pulsar is a distributed pub/sub messaging system with brokers, storage, and client libraries. Its topic model supports producers and subscribers, while a subscription retains messages until consumers acknowledge successful processing. A standalone mode runs the components in one JVM for local experimentation; a production installation uses a separate deployment design and operational plan.
Try the producer and consumer loop locally
The official standalone guide is explicitly for local development and testing. It walks through downloading the Pulsar distribution, starting a single-machine standalone service, then using the command-line client to produce and consume messages from a topic. A first task can be a small event such as invoice.created; the guide's CLI sample is illustrative. For application code, use a client library rather than relying on manual CLI messages. A subscription is the key to understanding how Pulsar handles work. The messaging guide explains that messages remain available while a consumer is disconnected and are discarded only after successful acknowledgments. That makes consumer acknowledgement and subscription configuration important: a consumer should confirm work only after it has processed the message, and teams need to decide how to handle retries and duplicate processing. Standalone mode places the cluster components in one JVM and is intended for local development, not as proof of production resilience. The Apache Pulsar repository is licensed under Apache License 2.0. Plan a production deployment separately, including its storage, broker, and client operations, rather than extrapolating from a laptop test.
Strengths
- Producers and consumers communicate through topics and subscriptions instead of being tightly coupled in one process.
- Subscriptions retain messages for disconnected consumers until processing is acknowledged.
- A local standalone guide lets developers try the broker and CLI before designing a larger deployment.
Watch out for
- Production deployment has more operational components than the single-JVM standalone mode.
- Consumers must handle acknowledgments, retries, and possible duplicate processing deliberately.
Best for
- Teams building event-driven services that need topic-based messaging and subscriptions.
- Applications that need consumers to resume retained messages after disconnecting.
- Developers evaluating a distributed messaging system with a local standalone setup before planning production.
Sources
- Apache Pulsar (Oct 25, 2026)
- Run a Standalone Pulsar Cluster Locally (Oct 25, 2026)
- Messaging Concepts (Oct 25, 2026)
- apache/pulsar (Oct 25, 2026)
- Apache Pulsar License (Oct 25, 2026)