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// Copyright 2020-2022 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"context"
"fmt"
"log"
"time"
"github.com/nats-io/nats.go"
"github.com/nats-io/nats.go/jetstream"
)
func main() {
ctx, cancel := context.WithTimeout(context.Background(), 60*time.Minute)
defer cancel()
nc, err := nats.Connect("nats://127.0.0.1:4222")
if err != nil {
log.Fatal(err)
}
js, err := jetstream.New(nc)
if err != nil {
log.Fatal(err)
}
s, err := js.CreateStream(ctx, jetstream.StreamConfig{
Name: "TEST_STREAM",
Subjects: []string{"FOO.*"},
})
if err != nil {
log.Fatal(err)
}
cons, err := s.CreateOrUpdateConsumer(ctx, jetstream.ConsumerConfig{
Durable: "TestConsumerListener",
AckPolicy: jetstream.AckExplicitPolicy,
})
if err != nil {
log.Fatal(err)
}
go endlessPublish(ctx, nc, js)
for {
msgs, err := cons.Fetch(100, jetstream.FetchMaxWait(1*time.Second))
if err != nil {
fmt.Println(err)
}
for msg := range msgs.Messages() {
fmt.Println(string(msg.Data()))
msg.Ack()
}
if msgs.Error() != nil {
fmt.Println("Error fetching messages: ", err)
}
}
}
func endlessPublish(ctx context.Context, nc *nats.Conn, js jetstream.JetStream) {
var i int
for {
time.Sleep(500 * time.Millisecond)
if nc.Status() != nats.CONNECTED {
continue
}
if _, err := js.Publish(ctx, "FOO.TEST1", []byte(fmt.Sprintf("msg %d", i))); err != nil {
fmt.Println("pub error: ", err)
}
i++
}
}
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