Memublikasikan dan menerima pesan di Pub/Sub menggunakan library klien

Memublikasikan dan menerima pesan di Pub/Sub menggunakan library klien

Halaman ini menunjukkan cara melakukan hal berikut:

• Buat project, aktifkan penagihan, dan aktifkan Pub/Sub Lite API menggunakan Google Cloud CLI.

• Buat reservasi Lite, topik Lite, dan langganan Lite menggunakan Google Cloud CLI.

• Kirim dan terima pesan menggunakan library klien Pub/Sub Lite untuk Go, Java, dan Python.

Sebelum memulai

1. Login ke akun Google Cloud Anda. Jika Anda baru menggunakan Google Cloud, buat akun untuk mengevaluasi performa produk kami dalam skenario dunia nyata. Pelanggan baru juga mendapatkan kredit gratis senilai $300 untuk menjalankan, menguji, dan men-deploy workload.
2. Menginstal Google Cloud CLI.

3. Untuk initialize gcloud CLI, jalankan perintah berikut:

   gcloud init

4. Buat atau pilih project Google Cloud.

   Catatan: Jika tidak berencana untuk menyimpan resource yang Anda buat dalam prosedur ini, buatlah project, bukan memilih project yang ada. Setelah menyelesaikan langkah ini, Anda dapat menghapus project, yang menghapus semua resource yang terkait dengan project ini.

   • Membuat project Google Cloud:

     gcloud projects create PROJECT_ID

     Ganti PROJECT_ID dengan nama untuk project Google Cloud yang Anda buat.

   • Pilih project Google Cloud yang Anda buat:

     gcloud config set project PROJECT_ID

     Ganti PROJECT_ID dengan nama project Google Cloud Anda.

5. Pastikan penagihan telah diaktifkan untuk project Google Cloud Anda.

6. Enable the Pub/Sub Lite API:

   gcloud services enable pubsublite.googleapis.com

7. Buat kredensial autentikasi lokal untuk Akun Google Anda:

   gcloud auth application-default login

8. Berikan peran ke Akun Google Anda. Jalankan perintah berikut satu kali untuk setiap peran IAM berikut: roles/pubsublite.admin

   gcloud projects add-iam-policy-binding PROJECT_ID --member="user:EMAIL_ADDRESS" --role=ROLE

   • Ganti PROJECT_ID dengan project ID Anda.
   • Ganti EMAIL_ADDRESS dengan alamat email Anda.
   • Ganti ROLE dengan setiap peran individual.
9. Menginstal Google Cloud CLI.

10. Untuk initialize gcloud CLI, jalankan perintah berikut:

    gcloud init

11. Buat atau pilih project Google Cloud.

    Catatan: Jika tidak berencana untuk menyimpan resource yang Anda buat dalam prosedur ini, buatlah project, bukan memilih project yang ada. Setelah menyelesaikan langkah ini, Anda dapat menghapus project, yang menghapus semua resource yang terkait dengan project ini.

    • Membuat project Google Cloud:

      gcloud projects create PROJECT_ID

      Ganti PROJECT_ID dengan nama untuk project Google Cloud yang Anda buat.

    • Pilih project Google Cloud yang Anda buat:

      gcloud config set project PROJECT_ID

      Ganti PROJECT_ID dengan nama project Google Cloud Anda.

12. Pastikan penagihan telah diaktifkan untuk project Google Cloud Anda.

13. Enable the Pub/Sub Lite API:

    gcloud services enable pubsublite.googleapis.com

14. Buat kredensial autentikasi lokal untuk Akun Google Anda:

    gcloud auth application-default login

15. Berikan peran ke Akun Google Anda. Jalankan perintah berikut satu kali untuk setiap peran IAM berikut: roles/pubsublite.admin

    gcloud projects add-iam-policy-binding PROJECT_ID --member="user:EMAIL_ADDRESS" --role=ROLE

    • Ganti PROJECT_ID dengan project ID Anda.
    • Ganti EMAIL_ADDRESS dengan alamat email Anda.
    • Ganti ROLE dengan setiap peran individual.

Menginstal library klien

Go

go get cloud.google.com/go/pubsublite

Java

Jika Anda menggunakan Maven, tambahkan kode berikut ke file pom.xml Anda: Untuk informasi lebih lanjut tentang BOM, lihat BOM Library Google Cloud Platform.

<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-pubsublite</artifactId>
  <version>1.13.1</version>
</dependency>
<dependency>
  <groupId>com.google.cloud</groupId>
  <artifactId>google-cloud-pubsub</artifactId>
  <version>1.127.3</version>
</dependency>

Jika menggunakan Gradle, tambahkan kode berikut ke dependensi Anda:

implementation 'com.google.cloud:google-cloud-pubsublite:1.13.2'

Jika Anda menggunakan sbt, tambahkan kode berikut ke dependensi Anda:

libraryDependencies += "com.google.cloud" % "google-cloud-pubsublite" % "1.13.2"

Jika menggunakan Visual Studio Code, IntelliJ, atau Eclipse, Anda dapat menambahkan library klien ke project menggunakan plugin IDE berikut:

• Cloud Code for VS Code
• Cloud Code for IntelliJ
• Cloud Tools for Eclipse

Plugin menyediakan fungsi tambahan, seperti pengelolaan kunci untuk akun layanan. Lihat dokumentasi setiap plugin untuk mengetahui detailnya.

Catatan: Library klien Cloud Java saat ini tidak mendukung Android.

Python

pip install --upgrade google-cloud-pubsublite

Membuat reservasi Lite

Untuk membuat reservasi Lite, gunakan perintah gcloud pubsub lite-reservations create. Contoh berikut membuat reservasi bernama testRes.

gcloud pubsub lite-reservations create testRes \
    --location=us-central1 \
    --throughput-capacity=1

Membuat topik Lite regional

Untuk membuat topik Lite regional, gunakan perintah gcloud pubsub lite-topics create. Contoh berikut membuat topik bernama testTopic.

gcloud pubsub lite-topics create testTopic \
    --location=us-central1 \
    --partitions=1 \
    --per-partition-bytes=30GiB \
    --throughput-reservation=projects/PROJECT_ID/locations/us-central1/reservations/testRes \

Ganti kode berikut:

PROJECT_ID: ID project

Membuat langganan Lite

Untuk membuat langganan Lite, gunakan perintah gcloud pubsub lite-subscriptions create. Contoh berikut membuat langganan bernama testSub.

gcloud pubsub lite-subscriptions create testSub \
    --location=us-central1 \
    --topic=testTopic \
    --delivery-requirement=deliver-immediately

Mengirim pesan

Kirim pesan ke topik Lite menggunakan aplikasi penerbit berikut:

Go

Sebelum mencoba contoh ini, ikuti petunjuk penyiapan Go di panduan memulai Pub/Sub Lite menggunakan library klien. Untuk mengetahui informasi selengkapnya, lihat dokumentasi referensi API Go Pub/Sub Lite.

Untuk melakukan autentikasi ke Pub/Sub Lite, siapkan Kredensial Default Aplikasi. Untuk mengetahui informasi selengkapnya, baca Menyiapkan autentikasi untuk lingkungan pengembangan lokal.

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"sync"

	"cloud.google.com/go/pubsub"
	"cloud.google.com/go/pubsublite/pscompat"
	"golang.org/x/sync/errgroup"
)

func main() {
	// NOTE: Set these flags for an existing Pub/Sub Lite topic when running this
	// sample.
	projectID := flag.String("project_id", "", "Cloud Project ID")
	zone := flag.String("zone", "", "Cloud Zone where the topic resides, e.g. us-central1-a")
	topicID := flag.String("topic_id", "", "Existing Pub/Sub Lite topic")
	messageCount := flag.Int("message_count", 100, "The number of messages to send")
	flag.Parse()

	ctx := context.Background()
	topicPath := fmt.Sprintf("projects/%s/locations/%s/topics/%s", *projectID, *zone, *topicID)

	// Create the publisher client.
	publisher, err := pscompat.NewPublisherClient(ctx, topicPath)
	if err != nil {
		log.Fatalf("pscompat.NewPublisherClient error: %v", err)
	}

	// Ensure the publisher will be shut down.
	defer publisher.Stop()

	// Collect any messages that need to be republished with a new publisher
	// client.
	var toRepublish []*pubsub.Message
	var toRepublishMu sync.Mutex

	// Publish messages. Messages are automatically batched.
	g := new(errgroup.Group)
	for i := 0; i < *messageCount; i++ {
		msg := &pubsub.Message{
			Data: []byte(fmt.Sprintf("message-%d", i)),
		}
		result := publisher.Publish(ctx, msg)

		g.Go(func() error {
			// Get blocks until the result is ready.
			id, err := result.Get(ctx)
			if err != nil {
				// NOTE: A failed PublishResult indicates that the publisher client
				// encountered a fatal error and has permanently terminated. After the
				// fatal error has been resolved, a new publisher client instance must
				// be created to republish failed messages.
				fmt.Printf("Publish error: %v\n", err)
				toRepublishMu.Lock()
				toRepublish = append(toRepublish, msg)
				toRepublishMu.Unlock()
				return err
			}

			// Metadata decoded from the id contains the partition and offset.
			metadata, err := pscompat.ParseMessageMetadata(id)
			if err != nil {
				fmt.Printf("Failed to parse message metadata %q: %v\n", id, err)
				return err
			}
			fmt.Printf("Published: partition=%d, offset=%d\n", metadata.Partition, metadata.Offset)
			return nil
		})
	}
	if err := g.Wait(); err != nil {
		fmt.Printf("Publishing finished with error: %v\n", err)
	}
	fmt.Printf("Published %d messages\n", *messageCount-len(toRepublish))

	// Print the error that caused the publisher client to terminate (if any),
	// which may contain more context than PublishResults.
	if err := publisher.Error(); err != nil {
		fmt.Printf("Publisher client terminated due to error: %v\n", publisher.Error())
	}
}

Java

import com.google.api.core.ApiFuture;
import com.google.api.core.ApiFutures;
import com.google.api.gax.rpc.ApiException;
import com.google.cloud.pubsublite.CloudRegion;
import com.google.cloud.pubsublite.CloudRegionOrZone;
import com.google.cloud.pubsublite.CloudZone;
import com.google.cloud.pubsublite.MessageMetadata;
import com.google.cloud.pubsublite.ProjectNumber;
import com.google.cloud.pubsublite.TopicName;
import com.google.cloud.pubsublite.TopicPath;
import com.google.cloud.pubsublite.cloudpubsub.Publisher;
import com.google.cloud.pubsublite.cloudpubsub.PublisherSettings;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.PubsubMessage;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ExecutionException;

public class PublisherExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String cloudRegion = "your-cloud-region";
    char zoneId = 'b';
    // Choose an existing topic for the publish example to work.
    String topicId = "your-topic-id";
    long projectNumber = Long.parseLong("123456789");
    int messageCount = 100;
    // True if using a regional location. False if using a zonal location.
    // https://cloud.google.com/pubsub/lite/docs/topics
    boolean regional = false;

    publisherExample(cloudRegion, zoneId, projectNumber, topicId, messageCount, regional);
  }

  // Publish messages to a topic.
  public static void publisherExample(
      String cloudRegion,
      char zoneId,
      long projectNumber,
      String topicId,
      int messageCount,
      boolean regional)
      throws ApiException, ExecutionException, InterruptedException {

    CloudRegionOrZone location;
    if (regional) {
      location = CloudRegionOrZone.of(CloudRegion.of(cloudRegion));
    } else {
      location = CloudRegionOrZone.of(CloudZone.of(CloudRegion.of(cloudRegion), zoneId));
    }

    TopicPath topicPath =
        TopicPath.newBuilder()
            .setProject(ProjectNumber.of(projectNumber))
            .setLocation(location)
            .setName(TopicName.of(topicId))
            .build();

    Publisher publisher = null;
    List<ApiFuture<String>> futures = new ArrayList<>();

    try {
      PublisherSettings publisherSettings =
          PublisherSettings.newBuilder().setTopicPath(topicPath).build();

      publisher = Publisher.create(publisherSettings);

      // Start the publisher. Upon successful starting, its state will become RUNNING.
      publisher.startAsync().awaitRunning();

      for (int i = 0; i < messageCount; i++) {
        String message = "message-" + i;

        // Convert the message to a byte string.
        ByteString data = ByteString.copyFromUtf8(message);
        PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();

        // Publish a message. Messages are automatically batched.
        ApiFuture<String> future = publisher.publish(pubsubMessage);
        futures.add(future);
      }
    } finally {
      ArrayList<MessageMetadata> metadata = new ArrayList<>();
      List<String> ackIds = ApiFutures.allAsList(futures).get();
      for (String id : ackIds) {
        // Decoded metadata contains partition and offset.
        metadata.add(MessageMetadata.decode(id));
      }
      System.out.println(metadata + "\nPublished " + ackIds.size() + " messages.");

      if (publisher != null) {
        // Shut down the publisher.
        publisher.stopAsync().awaitTerminated();
        System.out.println("Publisher is shut down.");
      }
    }
  }
}

Python

Sebelum mencoba contoh ini, ikuti petunjuk penyiapan Python di panduan memulai Pub/Sub Lite menggunakan library klien. Untuk mengetahui informasi selengkapnya, lihat dokumentasi referensi API Python Pub/Sub Lite.

Untuk melakukan autentikasi ke Pub/Sub Lite, siapkan Kredensial Default Aplikasi. Untuk mengetahui informasi selengkapnya, baca Menyiapkan autentikasi untuk lingkungan pengembangan lokal.

from google.cloud.pubsublite.cloudpubsub import PublisherClient
from google.cloud.pubsublite.types import (
    CloudRegion,
    CloudZone,
    MessageMetadata,
    TopicPath,
)

# TODO(developer):
# project_number = 1122334455
# cloud_region = "us-central1"
# zone_id = "a"
# topic_id = "your-topic-id"
# regional = True

if regional:
    location = CloudRegion(cloud_region)
else:
    location = CloudZone(CloudRegion(cloud_region), zone_id)

topic_path = TopicPath(project_number, location, topic_id)

# PublisherClient() must be used in a `with` block or have __enter__() called before use.
with PublisherClient() as publisher_client:
    data = "Hello world!"
    api_future = publisher_client.publish(topic_path, data.encode("utf-8"))
    # result() blocks. To resolve API futures asynchronously, use add_done_callback().
    message_id = api_future.result()
    message_metadata = MessageMetadata.decode(message_id)
    print(
        f"Published a message to {topic_path} with partition {message_metadata.partition.value} and offset {message_metadata.cursor.offset}."
    )

Penerbit tersebut mengirim 100 pesan ke topik Lite dan mencetak jumlah pesan yang diterima layanan Pub/Sub Lite.

Menerima pesan

Terima pesan dari langganan Lite menggunakan aplikasi pelanggan berikut:

Go

Sebelum mencoba contoh ini, ikuti petunjuk penyiapan Go di panduan memulai Pub/Sub Lite menggunakan library klien. Untuk mengetahui informasi selengkapnya, lihat dokumentasi referensi API Go Pub/Sub Lite.

Untuk melakukan autentikasi ke Pub/Sub Lite, siapkan Kredensial Default Aplikasi. Untuk mengetahui informasi selengkapnya, baca Menyiapkan autentikasi untuk lingkungan pengembangan lokal.

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"sync/atomic"
	"time"

	"cloud.google.com/go/pubsub"
	"cloud.google.com/go/pubsublite/pscompat"
)

func main() {
	// NOTE: Set these flags for an existing Pub/Sub Lite subscription containing
	// published messages when running this sample.
	projectID := flag.String("project_id", "", "Cloud Project ID")
	zone := flag.String("zone", "", "Cloud Zone where the topic resides, e.g. us-central1-a")
	subscriptionID := flag.String("subscription_id", "", "Existing Pub/Sub Lite subscription")
	timeout := flag.Duration("timeout", 90*time.Second, "The duration to receive messages")
	flag.Parse()

	ctx := context.Background()
	subscriptionPath := fmt.Sprintf("projects/%s/locations/%s/subscriptions/%s", *projectID, *zone, *subscriptionID)

	// Configure flow control settings. These settings apply per partition.
	// The message stream is paused based on the maximum size or number of
	// messages that the subscriber has already received, whichever condition is
	// met first.
	settings := pscompat.ReceiveSettings{
		// 10 MiB. Must be greater than the allowed size of the largest message
		// (1 MiB).
		MaxOutstandingBytes: 10 * 1024 * 1024,
		// 1,000 outstanding messages. Must be > 0.
		MaxOutstandingMessages: 1000,
	}

	// Create the subscriber client.
	subscriber, err := pscompat.NewSubscriberClientWithSettings(ctx, subscriptionPath, settings)
	if err != nil {
		log.Fatalf("pscompat.NewSubscriberClientWithSettings error: %v", err)
	}

	// Listen for messages until the timeout expires.
	log.Printf("Listening to messages on %s for %v...\n", subscriptionPath, *timeout)
	cctx, cancel := context.WithTimeout(ctx, *timeout)
	defer cancel()
	var receiveCount int32

	// Receive blocks until the context is cancelled or an error occurs.
	if err := subscriber.Receive(cctx, func(ctx context.Context, msg *pubsub.Message) {
		// NOTE: May be called concurrently; synchronize access to shared memory.
		atomic.AddInt32(&receiveCount, 1)

		// Metadata decoded from the message ID contains the partition and offset.
		metadata, err := pscompat.ParseMessageMetadata(msg.ID)
		if err != nil {
			log.Fatalf("Failed to parse %q: %v", msg.ID, err)
		}

		fmt.Printf("Received (partition=%d, offset=%d): %s\n", metadata.Partition, metadata.Offset, string(msg.Data))
		msg.Ack()
	}); err != nil {
		log.Fatalf("SubscriberClient.Receive error: %v", err)
	}

	fmt.Printf("Received %d messages\n", receiveCount)
}

Java

Sebelum mencoba contoh ini, ikuti petunjuk penyiapan Java di panduan memulai Pub/Sub Lite menggunakan library klien. Untuk mengetahui informasi selengkapnya, lihat dokumentasi referensi API Java Pub/Sub Lite.

Untuk melakukan autentikasi ke Pub/Sub Lite, siapkan Kredensial Default Aplikasi. Untuk mengetahui informasi selengkapnya, baca Menyiapkan autentikasi untuk lingkungan pengembangan lokal.

import com.google.api.gax.rpc.ApiException;
import com.google.cloud.pubsub.v1.AckReplyConsumer;
import com.google.cloud.pubsub.v1.MessageReceiver;
import com.google.cloud.pubsublite.CloudRegion;
import com.google.cloud.pubsublite.CloudRegionOrZone;
import com.google.cloud.pubsublite.CloudZone;
import com.google.cloud.pubsublite.MessageMetadata;
import com.google.cloud.pubsublite.ProjectNumber;
import com.google.cloud.pubsublite.SubscriptionName;
import com.google.cloud.pubsublite.SubscriptionPath;
import com.google.cloud.pubsublite.cloudpubsub.FlowControlSettings;
import com.google.cloud.pubsublite.cloudpubsub.MessageTransforms;
import com.google.cloud.pubsublite.cloudpubsub.Subscriber;
import com.google.cloud.pubsublite.cloudpubsub.SubscriberSettings;
import com.google.protobuf.Timestamp;
import com.google.pubsub.v1.PubsubMessage;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class SubscriberExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String cloudRegion = "your-cloud-region";
    char zoneId = 'b';
    // Choose an existing subscription for the subscribe example to work.
    String subscriptionId = "your-subscription-id";
    long projectNumber = Long.parseLong("123456789");
    // True if using a regional location. False if using a zonal location.
    // https://cloud.google.com/pubsub/lite/docs/topics
    boolean regional = false;

    subscriberExample(cloudRegion, zoneId, projectNumber, subscriptionId, regional);
  }

  public static void subscriberExample(
      String cloudRegion, char zoneId, long projectNumber, String subscriptionId, boolean regional)
      throws ApiException {

    CloudRegionOrZone location;
    if (regional) {
      location = CloudRegionOrZone.of(CloudRegion.of(cloudRegion));
    } else {
      location = CloudRegionOrZone.of(CloudZone.of(CloudRegion.of(cloudRegion), zoneId));
    }

    SubscriptionPath subscriptionPath =
        SubscriptionPath.newBuilder()
            .setLocation(location)
            .setProject(ProjectNumber.of(projectNumber))
            .setName(SubscriptionName.of(subscriptionId))
            .build();

    // The message stream is paused based on the maximum size or number of messages that the
    // subscriber has already received, whichever condition is met first.
    FlowControlSettings flowControlSettings =
        FlowControlSettings.builder()
            // 10 MiB. Must be greater than the allowed size of the largest message (1 MiB).
            .setBytesOutstanding(10 * 1024 * 1024L)
            // 1,000 outstanding messages. Must be >0.
            .setMessagesOutstanding(1000L)
            .build();

    MessageReceiver receiver =
        (PubsubMessage message, AckReplyConsumer consumer) -> {
          System.out.println("Id : " + MessageMetadata.decode(message.getMessageId()));
          System.out.println("Data : " + message.getData().toStringUtf8());
          System.out.println("Ordering key : " + message.getOrderingKey());
          System.out.println("Attributes : ");
          message
              .getAttributesMap()
              .forEach(
                  (key, value) -> {
                    if (key == MessageTransforms.PUBSUB_LITE_EVENT_TIME_TIMESTAMP_PROTO) {
                      Timestamp ts = MessageTransforms.decodeAttributeEventTime(value);
                      System.out.println(key + " = " + ts.toString());
                    } else {
                      System.out.println(key + " = " + value);
                    }
                  });

          // Acknowledge the message.
          consumer.ack();
        };

    SubscriberSettings subscriberSettings =
        SubscriberSettings.newBuilder()
            .setSubscriptionPath(subscriptionPath)
            .setReceiver(receiver)
            // Flow control settings are set at the partition level.
            .setPerPartitionFlowControlSettings(flowControlSettings)
            .build();

    Subscriber subscriber = Subscriber.create(subscriberSettings);

    // Start the subscriber. Upon successful starting, its state will become RUNNING.
    subscriber.startAsync().awaitRunning();

    System.out.println("Listening to messages on " + subscriptionPath.toString() + "...");

    try {
      System.out.println(subscriber.state());
      // Wait 90 seconds for the subscriber to reach TERMINATED state. If it encounters
      // unrecoverable errors before then, its state will change to FAILED and an
      // IllegalStateException will be thrown.
      subscriber.awaitTerminated(90, TimeUnit.SECONDS);
    } catch (TimeoutException t) {
      // Shut down the subscriber. This will change the state of the subscriber to TERMINATED.
      subscriber.stopAsync().awaitTerminated();
      System.out.println("Subscriber is shut down: " + subscriber.state());
    }
  }
}

Python

Sebelum mencoba contoh ini, ikuti petunjuk penyiapan Python di panduan memulai Pub/Sub Lite menggunakan library klien. Untuk mengetahui informasi selengkapnya, lihat dokumentasi referensi API Python Pub/Sub Lite.

Untuk melakukan autentikasi ke Pub/Sub Lite, siapkan Kredensial Default Aplikasi. Untuk mengetahui informasi selengkapnya, baca Menyiapkan autentikasi untuk lingkungan pengembangan lokal.

from concurrent.futures._base import TimeoutError
from google.pubsub_v1 import PubsubMessage
from google.cloud.pubsublite.cloudpubsub import SubscriberClient
from google.cloud.pubsublite.types import (
    CloudRegion,
    CloudZone,
    FlowControlSettings,
    MessageMetadata,
    SubscriptionPath,
)

# TODO(developer):
# project_number = 1122334455
# cloud_region = "us-central1"
# zone_id = "a"
# subscription_id = "your-subscription-id"
# timeout = 90
# regional = True

if regional:
    location = CloudRegion(cloud_region)
else:
    location = CloudZone(CloudRegion(cloud_region), zone_id)

subscription_path = SubscriptionPath(project_number, location, subscription_id)
# Configure when to pause the message stream for more incoming messages based on the
# maximum size or number of messages that a single-partition subscriber has received,
# whichever condition is met first.
per_partition_flow_control_settings = FlowControlSettings(
    # 1,000 outstanding messages. Must be >0.
    messages_outstanding=1000,
    # 10 MiB. Must be greater than the allowed size of the largest message (1 MiB).
    bytes_outstanding=10 * 1024 * 1024,
)

def callback(message: PubsubMessage):
    message_data = message.data.decode("utf-8")
    metadata = MessageMetadata.decode(message.message_id)
    print(
        f"Received {message_data} of ordering key {message.ordering_key} with id {metadata}."
    )
    message.ack()

# SubscriberClient() must be used in a `with` block or have __enter__() called before use.
with SubscriberClient() as subscriber_client:

    streaming_pull_future = subscriber_client.subscribe(
        subscription_path,
        callback=callback,
        per_partition_flow_control_settings=per_partition_flow_control_settings,
    )

    print(f"Listening for messages on {str(subscription_path)}...")

    try:
        streaming_pull_future.result(timeout=timeout)
    except TimeoutError or KeyboardInterrupt:
        streaming_pull_future.cancel()
        assert streaming_pull_future.done()

Setelah menerima pesan, pelanggan akan mencetak ID pesan dan data pesan.

Pembersihan

Agar tidak menimbulkan biaya pada akun Google Cloud Anda untuk resource yang digunakan pada halaman ini, hapus project Google Cloud yang berisi resource tersebut.

1. Agar tidak menimbulkan biaya pada akun Google Cloud Anda untuk resource yang digunakan dalam panduan ini, hapus topik dan langganan.

   gcloud pubsub lite-subscriptions delete testSub --location=us-central1
   gcloud pubsub lite-topics delete testTopic --location=us-central1
   

2. Opsional: Cabut kredensial autentikasi yang Anda buat, dan hapus file kredensial lokal.

   gcloud auth application-default revoke

3. Opsional: Cabut kredensial dari gcloud CLI.

   gcloud auth revoke

Langkah selanjutnya

• Pelajari lebih lanjut tentang topik Lite dan langganan Lite.
• Pelajari lebih lanjut cara mengirim dan menerima pesan.
• Pelajari contoh kode untuk library klien.