natsio (Dart)

A pure Dart client for NATS, ported from nats.go. Supports core NATS, headers, request/reply, JetStream, Key-Value, Object Store, and Micro.

Install

Add to pubspec.yaml:

dependencies:
  natsio: ^0.1.0

If you are consuming from Git:

dependencies:
  natsio:
    git:
      url: git@github.com:policyaid/nats.dart.git

Quick Start

import 'package:natsio/nats.dart';

Future<void> main() async {
  final client = Client(
    options: ClientOptions(servers: ['nats://127.0.0.1:4222']),
  );

  await client.connect();

  final sub = client.subscribe('greet');
  sub.listen((msg) {
    print('got: ${msg.stringData}');
  });

  client.publishString('greet', 'hello');
  await client.flush();

  await client.drain();
}

Request/Reply

final msg = await client.requestString(
  'echo',
  'ping',
  timeout: Duration(seconds: 1),
);
print(msg.stringData);

Headers and No-Responders

client.publish(
  'foo',
  Uint8List.fromList([1, 2, 3]),
  headers: {'X-Trace': ['abc123']},
);

final msg = await client.requestString('svc.ping', 'hi');
if (msg.isNoResponders) {
  print('no responders');
}

JetStream

final js = JetStream(client);
await js.addStream(StreamConfig(
  name: 'EVENTS',
  subjects: ['events.>'],
));

await js.publishString('events.1', 'hello');

Key-Value

final js = JetStream(client);
final kv = await js.keyValue('CONFIG');
await kv.putString('feature', 'on');
final entry = await kv.get('feature');
print(entry?.stringValue);

Object Store

final js = JetStream(client);
final store = await js.objectStore('ASSETS');
await store.putString('logo.txt', 'hello');
final obj = await store.getString('logo.txt');
print(obj);

Running NATS Locally

docker run --rm -p 4222:4222 -p 8222:8222 -p 6222:6222 nats:latest -js

Testing

cd nats.dart
dart test

Integration tests will start a Docker NATS server automatically if nats-server is not in PATH.