Cette page a été traduite par l'API Cloud Translation.
Switch to English

Créer un abonnement avec une règle concernant les lettres mortes

Crée un abonnement qui transfère les messages non distribuables vers un sujet des lettres mortes.

Pages de documentation incluant cet exemple de code

Pour afficher l'exemple de code utilisé en contexte, consultez la documentation suivante :

Exemple de code

C#

Avant d'essayer cet exemple, suivez les instructions de configuration de C# décrites dans le Guide de démarrage rapide de Pub/Sub – Utiliser des bibliothèques clientes. Pour en savoir plus, consultez la documentation de référence sur l'API Pub/Sub pour C#.


using Google.Cloud.PubSub.V1;
using System;

public class CreateSubscriptionWithDeadLetterPolicySample
{
    public Subscription CreateSubscriptionWithDeadLetterPolicy(string projectId, string subscriptionId, string topicId, string deadLetterTopicId)
    {
        SubscriberServiceApiClient subscriber = SubscriberServiceApiClient.Create();
        // This is the subscription you want to create with a dead letter policy.
        var subscriptionName = SubscriptionName.FromProjectSubscription(projectId, subscriptionId);
        // This is an existing topic that you want to attach the subscription with dead letter policy to.
        var topicName = TopicName.FromProjectTopic(projectId, topicId);
        // This is an existing topic that the subscription with dead letter policy forwards dead letter messages to.
        var deadLetterTopic = TopicName.FromProjectTopic(projectId, deadLetterTopicId).ToString();
        var subscriptionRequest = new Subscription
        {
            SubscriptionName = subscriptionName,
            TopicAsTopicName = topicName,
            DeadLetterPolicy = new DeadLetterPolicy
            {
                DeadLetterTopic = deadLetterTopic,
                // The maximum number of times that the service attempts to deliver a
                // message before forwarding it to the dead letter topic. Must be [5-100].
                MaxDeliveryAttempts = 10
            },
            AckDeadlineSeconds = 30
        };

        var subscription = subscriber.CreateSubscription(subscriptionRequest);
        Console.WriteLine("Created subscription: " + subscription.SubscriptionName.SubscriptionId);
        Console.WriteLine($"It will forward dead letter messages to: {subscription.DeadLetterPolicy.DeadLetterTopic}");
        Console.WriteLine($"After {subscription.DeadLetterPolicy.MaxDeliveryAttempts} delivery attempts.");
        // Remember to attach a subscription to the dead letter topic because
        // messages published to a topic with no subscriptions are lost.
        return subscription;
    }
}

C++

Avant d'essayer cet exemple, suivez les instructions de configuration de C++ décrites dans le Guide de démarrage rapide de Pub/Sub – Utiliser des bibliothèques clientes. Pour en savoir plus, consultez la documentation de référence sur l'API Pub/Sub pour C++.

namespace pubsub = google::cloud::pubsub;
[](pubsub::SubscriptionAdminClient client, std::string const& project_id,
   std::string const& topic_id, std::string const& subscription_id,
   std::string const& dead_letter_topic_id,
   int dead_letter_delivery_attempts) {
  auto sub = client.CreateSubscription(
      pubsub::Topic(project_id, std::move(topic_id)),
      pubsub::Subscription(project_id, std::move(subscription_id)),
      pubsub::SubscriptionBuilder{}.set_dead_letter_policy(
          pubsub::SubscriptionBuilder::MakeDeadLetterPolicy(
              pubsub::Topic(project_id, dead_letter_topic_id),
              dead_letter_delivery_attempts)));
  if (sub.status().code() == google::cloud::StatusCode::kAlreadyExists) {
    std::cout << "The subscription already exists\n";
    return;
  }
  if (!sub) throw std::runtime_error(sub.status().message());

  std::cout << "The subscription was successfully created: "
            << sub->DebugString() << "\n";

  std::cout << "It will forward dead letter messages to: "
            << sub->dead_letter_policy().dead_letter_topic() << "\n";

  std::cout << "After " << sub->dead_letter_policy().max_delivery_attempts()
            << " delivery attempts.\n";
}

Go

Avant d'essayer cet exemple, suivez les instructions de configuration de Go décrites dans le Guide de démarrage rapide de Pub/Sub – Utiliser des bibliothèques clientes. Pour en savoir plus, consultez la documentation de référence sur l'API Pub/Sub pour Go.

import (
	"context"
	"fmt"
	"io"
	"time"

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

// createSubWithDeadLetter creates a subscription with a dead letter policy.
func createSubWithDeadLetter(w io.Writer, projectID, subID string, topicID string, fullyQualifiedDeadLetterTopic string) error {
	// projectID := "my-project-id"
	// subID := "my-sub"
	// topicID := "my-topic"
	// fullyQualifiedDeadLetterTopic := "projects/my-project/topics/my-dead-letter-topic"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %v", err)
	}

	topic := client.Topic(topicID)

	subConfig := pubsub.SubscriptionConfig{
		Topic:       topic,
		AckDeadline: 20 * time.Second,
		DeadLetterPolicy: &pubsub.DeadLetterPolicy{
			DeadLetterTopic:     fullyQualifiedDeadLetterTopic,
			MaxDeliveryAttempts: 10,
		},
	}

	sub, err := client.CreateSubscription(ctx, subID, subConfig)
	if err != nil {
		return fmt.Errorf("CreateSubscription: %v", err)
	}
	fmt.Fprintf(w, "Created subscription (%s) with dead letter topic (%s)\n", sub.String(), fullyQualifiedDeadLetterTopic)
	fmt.Fprintln(w, "To process dead letter messages, remember to add a subscription to your dead letter topic.")
	return nil
}

Java

Avant d'essayer cet exemple, suivez les instructions de configuration de Java décrites dans le Guide de démarrage rapide de Pub/Sub – Utiliser des bibliothèques clientes. Pour en savoir plus, consultez la documentation de référence sur l'API Pub/Sub pour Java.

import com.google.cloud.pubsub.v1.SubscriptionAdminClient;
import com.google.pubsub.v1.DeadLetterPolicy;
import com.google.pubsub.v1.ProjectSubscriptionName;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.Subscription;
import java.io.IOException;

public class CreateSubscriptionWithDeadLetterPolicyExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    // This is the subscription you want to create with a dead letter policy.
    String subscriptionId = "your-subscription-id";
    // This is an existing topic that you want to attach the subscription with dead letter policy
    // to.
    String topicId = "your-topic-id";
    // This is an existing topic that the subscription with dead letter policy forwards dead letter
    // messages to.
    String deadLetterTopicId = "your-dead-letter-topic-id";

    CreateSubscriptionWithDeadLetterPolicyExample.createSubscriptionWithDeadLetterPolicyExample(
        projectId, subscriptionId, topicId, deadLetterTopicId);
  }

  public static void createSubscriptionWithDeadLetterPolicyExample(
      String projectId, String subscriptionId, String topicId, String deadLetterTopicId)
      throws IOException {
    try (SubscriptionAdminClient subscriptionAdminClient = SubscriptionAdminClient.create()) {

      ProjectTopicName topicName = ProjectTopicName.of(projectId, topicId);
      ProjectSubscriptionName subscriptionName =
          ProjectSubscriptionName.of(projectId, subscriptionId);
      ProjectTopicName deadLetterTopicName = ProjectTopicName.of(projectId, deadLetterTopicId);

      DeadLetterPolicy deadLetterPolicy =
          DeadLetterPolicy.newBuilder()
              .setDeadLetterTopic(deadLetterTopicName.toString())
              // The maximum number of times that the service attempts to deliver a
              // message before forwarding it to the dead letter topic. Must be [5-100].
              .setMaxDeliveryAttempts(10)
              .build();

      Subscription request =
          Subscription.newBuilder()
              .setName(subscriptionName.toString())
              .setTopic(topicName.toString())
              .setDeadLetterPolicy(deadLetterPolicy)
              .build();

      Subscription subscription = subscriptionAdminClient.createSubscription(request);

      System.out.println("Created subscription: " + subscription.getName());
      System.out.println(
          "It will forward dead letter messages to: "
              + subscription.getDeadLetterPolicy().getDeadLetterTopic());
      System.out.println(
          "After "
              + subscription.getDeadLetterPolicy().getMaxDeliveryAttempts()
              + " delivery attempts.");
      // Remember to attach a subscription to the dead letter topic because
      // messages published to a topic with no subscriptions are lost.
    }
  }
}

Node.js

Avant d'essayer cet exemple, suivez les instructions de configuration de Node.js décrites dans le Guide de démarrage rapide de Pub/Sub – Utiliser des bibliothèques clientes. Pour en savoir plus, consultez la documentation de référence sur l'API Pub/Sub pour Node.js.

/**
 * TODO(developer): Uncomment these variables before running the sample.
 */
// const topicName = 'YOUR_TOPIC_NAME';
// const subscriptionName = 'YOUR_SUBSCRIPTION_NAME';
// const deadLetterTopicName = 'YOUR_DEAD_LETTER_TOPIC_NAME';

// Imports the Google Cloud client library
const {PubSub} = require('@google-cloud/pubsub');

// Creates a client; cache this for further use
const pubSubClient = new PubSub();

async function createSubscriptionWithDeadLetterPolicy() {
  // Creates a new subscription
  await pubSubClient.topic(topicName).createSubscription(subscriptionName, {
    deadLetterPolicy: {
      deadLetterTopic: pubSubClient.topic(deadLetterTopicName).name,
      maxDeliveryAttempts: 10,
    },
  });
  console.log(
    `Created subscription ${subscriptionName} with dead letter topic ${deadLetterTopicName}.`
  );
  console.log(
    'To process dead letter messages, remember to add a subscription to your dead letter topic.'
  );
}

createSubscriptionWithDeadLetterPolicy().catch(console.error);

PHP

Avant d'essayer cet exemple, suivez les instructions de configuration de PHP décrites dans le Guide de démarrage rapide de Pub/Sub – Utiliser des bibliothèques clientes. Pour en savoir plus, consultez la documentation de référence sur l'API Pub/Sub pour PHP.

use Google\Cloud\PubSub\PubSubClient;

/**
 * Creates a Pub/Sub subscription with dead letter policy enabled.
 *
 * @param string $projectId  The Google project ID.
 * @param string $topicName  The Pub/Sub topic name.
 * @param string $subscriptionName  The Pub/Sub subscription name.
 * @param string $deadLetterTopicName The Pub/Sub topic to use for dead letter policy.
 */
function dead_letter_create_subscription($projectId, $topicName, $subscriptionName, $deadLetterTopicName)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);

    $topic = $pubsub->topic($topicName);
    $deadLetterTopic = $pubsub->topic($deadLetterTopicName);

    $subscription = $topic->subscribe($subscriptionName, [
        'deadLetterPolicy' => [
            'deadLetterTopic' => $deadLetterTopic
        ]
    ]);

    printf(
        'Subscription %s created with dead letter topic %s' . PHP_EOL,
        $subscription->name(),
        $deadLetterTopic->name()
    );
}

Python

Avant d'essayer cet exemple, suivez les instructions de configuration de Python décrites dans le Guide de démarrage rapide de Pub/Sub – Utiliser des bibliothèques clientes. Pour en savoir plus, consultez la documentation de référence sur l'API Pub/Sub pour Python.

from google.cloud import pubsub_v1
from google.cloud.pubsub_v1.types import DeadLetterPolicy

# TODO(developer)
# project_id = "your-project-id"
# endpoint = "https://my-test-project.appspot.com/push"
# TODO(developer): This is an existing topic that the subscription
# with dead letter policy is attached to.
# topic_id = "your-topic-id"
# TODO(developer): This is an existing subscription with a dead letter policy.
# subscription_id = "your-subscription-id"
# TODO(developer): This is an existing dead letter topic that the subscription
# with dead letter policy will forward dead letter messages to.
# dead_letter_topic_id = "your-dead-letter-topic-id"
# TODO(developer): This is the maximum number of delivery attempts allowed
# for a message before it gets delivered to a dead letter topic.
# max_delivery_attempts = 5

publisher = pubsub_v1.PublisherClient()
subscriber = pubsub_v1.SubscriberClient()

topic_path = publisher.topic_path(project_id, topic_id)
subscription_path = subscriber.subscription_path(project_id, subscription_id)
dead_letter_topic_path = publisher.topic_path(project_id, dead_letter_topic_id)

dead_letter_policy = DeadLetterPolicy(
    dead_letter_topic=dead_letter_topic_path,
    max_delivery_attempts=max_delivery_attempts,
)

with subscriber:
    request = {
        "name": subscription_path,
        "topic": topic_path,
        "dead_letter_policy": dead_letter_policy,
    }
    subscription = subscriber.create_subscription(request)

print(f"Subscription created: {subscription.name}")
print(
    f"It will forward dead letter messages to: {subscription.dead_letter_policy.dead_letter_topic}."
)
print(
    f"After {subscription.dead_letter_policy.max_delivery_attempts} delivery attempts."
)

Ruby

Avant d'essayer cet exemple, suivez les instructions de configuration de Ruby décrites dans le Guide de démarrage rapide de Pub/Sub – Utiliser des bibliothèques clientes. Pour en savoir plus, consultez la documentation de référence sur l'API Pub/Sub pour Ruby.

# topic_name             = "Your Pubsub topic name"
# subscription_name      = "Your Pubsub subscription name"
# dead_letter_topic_name = "Your Pubsub dead letter topic name"
require "google/cloud/pubsub"

pubsub = Google::Cloud::Pubsub.new

topic             = pubsub.topic topic_name
dead_letter_topic = pubsub.topic dead_letter_topic_name
subscription      = topic.subscribe subscription_name,
                                    dead_letter_topic:                 dead_letter_topic,
                                    dead_letter_max_delivery_attempts: 10

puts "Created subscription #{subscription_name} with dead letter topic #{dead_letter_topic_name}."
puts "To process dead letter messages, remember to add a subscription to your dead letter topic."