snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

_examples/pubsubs/nats-streaming/main.go

@@ -0,0 +1,82 @@
+// Sources for https://watermill.io/learn/getting-started/
+package main
+
+import (
+	"context"
+	"log"
+	"time"
+
+	stan "github.com/nats-io/stan.go"
+
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill-nats/pkg/nats"
+	"github.com/ThreeDotsLabs/watermill/message"
+)
+
+func main() {
+	subscriber, err := nats.NewStreamingSubscriber(
+		nats.StreamingSubscriberConfig{
+			ClusterID:        "test-cluster",
+			ClientID:         "example-subscriber",
+			QueueGroup:       "example",
+			DurableName:      "my-durable",
+			SubscribersCount: 4, // how many goroutines should consume messages
+			CloseTimeout:     time.Minute,
+			AckWaitTimeout:   time.Second * 30,
+			StanOptions: []stan.Option{
+				stan.NatsURL("nats://nats-streaming:4222"),
+			},
+			Unmarshaler: nats.GobMarshaler{},
+		},
+		watermill.NewStdLogger(false, false),
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	messages, err := subscriber.Subscribe(context.Background(), "example.topic")
+	if err != nil {
+		panic(err)
+	}
+
+	go process(messages)
+
+	publisher, err := nats.NewStreamingPublisher(
+		nats.StreamingPublisherConfig{
+			ClusterID: "test-cluster",
+			ClientID:  "example-publisher",
+			StanOptions: []stan.Option{
+				stan.NatsURL("nats://nats-streaming:4222"),
+			},
+			Marshaler: nats.GobMarshaler{},
+		},
+		watermill.NewStdLogger(false, false),
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	publishMessages(publisher)
+}
+
+func publishMessages(publisher message.Publisher) {
+	for {
+		msg := message.NewMessage(watermill.NewUUID(), []byte("Hello, world!"))
+
+		if err := publisher.Publish("example.topic", msg); err != nil {
+			panic(err)
+		}
+
+		time.Sleep(time.Second)
+	}
+}
+
+func process(messages <-chan *message.Message) {
+	for msg := range messages {
+		log.Printf("received message: %s, payload: %s", msg.UUID, string(msg.Payload))
+
+		// we need to Acknowledge that we received and processed the message,
+		// otherwise, it will be resent over and over again.
+		msg.Ack()
+	}
+}