+
wg := sync.WaitGroup{}
+wg.Add(1)
+
+errCh := make(chan error, 1)
+
+// To simulate a timeout, you would set the DrainTimeout()
+// to a value less than the time spent in the message callback,
+// so say: nats.DrainTimeout(10*time.Millisecond).
+
+nc, err := nats.Connect("demo.nats.io",
+ nats.DrainTimeout(10*time.Second),
+ nats.ErrorHandler(func(_ *nats.Conn, _ *nats.Subscription, err error) {
+ errCh <- err
+ }),
+ nats.ClosedHandler(func(_ *nats.Conn) {
+ wg.Done()
+ }))
+if err != nil {
+ log.Fatal(err)
+}
+
+// Subscribe, but add some delay while processing.
+if _, err := nc.Subscribe("foo", func(_ *nats.Msg) {
+ time.Sleep(200 * time.Millisecond)
+}); err != nil {
+ log.Fatal(err)
+}
+
+// Publish a message
+if err := nc.Publish("foo", []byte("hello")); err != nil {
+ log.Fatal(err)
+}
+
+// Drain the connection, which will close it when done.
+if err := nc.Drain(); err != nil {
+ log.Fatal(err)
+}
+
+// Wait for the connection to be closed.
+wg.Wait()
+
+// Check if there was an error
+select {
+case e := <-errCh:
+ log.Fatal(e)
+default:
+}
+
+
+
+
Connection nc = Nats.connect("nats://demo.nats.io:4222");
+
+// Use a latch to wait for a message to arrive
+CountDownLatch latch = new CountDownLatch(1);
+
+// Create a dispatcher and inline message handler
+Dispatcher d = nc.createDispatcher((msg) -> {
+ String str = new String(msg.getData(), StandardCharsets.UTF_8);
+ System.out.println(str);
+ latch.countDown();
+});
+
+// Subscribe
+d.subscribe("updates");
+
+// Wait for a message to come in
+latch.await();
+
+// Drain the connection, which will close it
+CompletableFuture<Boolean> drained = nc.drain(Duration.ofSeconds(10));
+
+// Wait for the drain to complete
+drained.get();
+
+
+
import asyncio
+from nats.aio.client import Client as NATS
+
+async def example(loop):
+ nc = NATS()
+
+ await nc.connect("nats://127.0.0.1:4222", loop=loop)
+
+ async def handler(msg):
+ print("[Received] ", msg)
+ await nc.publish(msg.reply, b'I can help')
+
+ # Can check whether client is in draining state
+ if nc.is_draining:
+ print("Connection is draining")
+
+ await nc.subscribe("help", "workers", cb=handler)
+ await nc.flush()
+
+ requests = []
+ for i in range(0, 10):
+ request = nc.request("help", b'help!', timeout=1)
+ requests.append(request)
+
+ # Wait for all the responses
+ responses = []
+ responses = await asyncio.gather(*requests)
+
+ # Gracefully close the connection.
+ await nc.drain()
+
+ print("Received {} responses".format(len(responses)))
+
+
+
NATS.start(drain_timeout: 1) do |nc|
+ NATS.subscribe('foo', queue: "workers") do |msg, reply, sub|
+ nc.publish(reply, "ACK:#{msg}")
+ end
+
+ NATS.subscribe('bar', queue: "workers") do |msg, reply, sub|
+ nc.publish(reply, "ACK:#{msg}")
+ end
+
+ NATS.subscribe('quux', queue: "workers") do |msg, reply, sub|
+ nc.publish(reply, "ACK:#{msg}")
+ end
+
+ EM.add_timer(2) do
+ next if NATS.draining?
+
+ # Drain gracefully closes the connection.
+ NATS.drain do
+ puts "Done draining. Connection is closed."
+ end
+ end
+end
+
+
+
let sub = await nc.subscribe('updates', (err, msg) => {
+ t.log('worker got message', msg.data);
+}, {queue: "workers"});
+// [end drain_sub]
+nc.flush();
+
+await nc.drain();
+// client must close when the connection drain resolves
+nc.close();
+
+