NATS PubSub Starter Template

This example project shows a basic setup of NATS JetStream publisher / subscriber using Watermill. The application runs in a loop, consuming events from a NATS JetStream.

This is an example for NATS push-based consumers. For pull-based consumers, see this branch.

There's a docker-compose file included, so you can run the example and see it in action.

Files

• main.go - example source code
• docker-compose.yml - local environment Docker Compose configuration
• go.mod - Go modules dependencies, you can find more information at Go wiki
• go.sum - Go modules checksums

Requirements

To run this example you will need Docker and docker-compose installed. See the installation guide.

Result

subscriber1 and subscriber2 represent two subscriptions bound to the same consumer my-durable with queue group example, and they both subscribe to example_topic.>. In each round, publisher publishes four messages to example_topic.a, example_topic.b, example_topic.a.test, and example_topic.b.test respectively. We can see that both subscriber1 and subscriber2 can receive messages from all four subjects, and each message is processed only once by either subscriber1 or subscriber2 since they are in the same queue group.

> docker-compose up

2023/09/20 12:03:07 [subscriber1] received message: 0, payload: hello from a
2023/09/20 12:03:07 [subscriber1] received message: 0, payload: hello from b
2023/09/20 12:03:07 [subscriber2] received message: 0, payload: hello from a.test
2023/09/20 12:03:07 [subscriber2] received message: 0, payload: hello from b.test
2023/09/20 12:03:08 [subscriber2] received message: 1, payload: hello from a
2023/09/20 12:03:08 [subscriber2] received message: 1, payload: hello from b
2023/09/20 12:03:08 [subscriber2] received message: 1, payload: hello from a.test
2023/09/20 12:03:08 [subscriber1] received message: 1, payload: hello from b.test
2023/09/20 12:03:09 [subscriber1] received message: 2, payload: hello from a
2023/09/20 12:03:09 [subscriber1] received message: 2, payload: hello from b
2023/09/20 12:03:09 [subscriber1] received message: 2, payload: hello from a.test
2023/09/20 12:03:09 [subscriber2] received message: 2, payload: hello from b.test
2023/09/20 12:03:10 [subscriber2] received message: 3, payload: hello from a
2023/09/20 12:03:10 [subscriber1] received message: 3, payload: hello from b
2023/09/20 12:03:10 [subscriber1] received message: 3, payload: hello from a.test
2023/09/20 12:03:10 [subscriber1] received message: 3, payload: hello from b.test
...