A toolkit to build distributed services in Typescript on top of Nats. It exposes a straightforward API abstracting most of the complexity of using Nats with sensible defaults and fully typed. It takes care of common scenarios such as payload validation, retry and more.

// Declare your payload types using zod schemas
const subscriptions = {
  'foo.bar': z.object({
    message: z.string(),
  }),
};

// Build a broker, passing in your types
const broker = await getBroker({ subscriptions });

// Use the broker with complete type inference
broker.subscribe('foo.bar', ({ data }) => {
  console.log(data.message); // Type = { message: string }
});

broker.publish('foo.bar', (wrap) => wrap({ message: 'hello' }));
broker.publish('foo.bar', (wrap) => wrap(10)); // Argument of type 'number' is not assignable to parameter of type '{ message: string; }'

The toolkit provides three different means of communicating.

Subscriptions are based on the base Nats subscriptions, offering a simple fire and forget mechanism. Messages are not guaranteed to be delivered and no acknowledgement is sent back to the publisher.

Similar to subscriptions but the sender receives a response from the listener, similarly to a classical client-server architecture with a request and a response.

Consumers are based on Nats JetStreams to offer messages retention. Using this mechanism guarantees that messages are delivered.