Message de publication Pub/Sub

Cette page fournit un exemple d'interaction avec Pub/Sub à partir de Cloud Functions.

Exemple de code

Java

Pour vous authentifier auprès de Cloud Run Functions, configurez le service Identifiants par défaut de l'application. Pour en savoir plus, consultez Configurer l'authentification pour un environnement de développement local.

import com.google.cloud.functions.HttpFunction;
import com.google.cloud.functions.HttpRequest;
import com.google.cloud.functions.HttpResponse;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.ProjectTopicName;
import com.google.pubsub.v1.PubsubMessage;
import java.io.BufferedWriter;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.nio.charset.StandardCharsets;
import java.util.Optional;
import java.util.concurrent.ExecutionException;
import java.util.logging.Level;
import java.util.logging.Logger;

public class PublishMessage implements HttpFunction {
  // TODO<developer> set this environment variable
  private static final String PROJECT_ID = System.getenv("GOOGLE_CLOUD_PROJECT");

  private static final Logger logger = Logger.getLogger(PublishMessage.class.getName());

  @Override
  public void service(HttpRequest request, HttpResponse response) throws IOException {
    Optional<String> maybeTopicName = request.getFirstQueryParameter("topic");
    Optional<String> maybeMessage = request.getFirstQueryParameter("message");

    BufferedWriter responseWriter = response.getWriter();

    if (maybeTopicName.isEmpty() || maybeMessage.isEmpty()) {
      response.setStatusCode(HttpURLConnection.HTTP_BAD_REQUEST);

      responseWriter.write("Missing 'topic' and/or 'message' parameter(s).");
      return;
    }

    String topicName = maybeTopicName.get();
    logger.info("Publishing message to topic: " + topicName);

    // Create the PubsubMessage object
    // (This is different than the PubsubMessage POJO used in Pub/Sub-triggered functions)
    ByteString byteStr = ByteString.copyFrom(maybeMessage.get(), StandardCharsets.UTF_8);
    PubsubMessage pubsubApiMessage = PubsubMessage.newBuilder().setData(byteStr).build();

    Publisher publisher = Publisher.newBuilder(
        ProjectTopicName.of(PROJECT_ID, topicName)).build();

    // Attempt to publish the message
    String responseMessage;
    try {
      publisher.publish(pubsubApiMessage).get();
      responseMessage = "Message published.";
    } catch (InterruptedException | ExecutionException e) {
      logger.log(Level.SEVERE, "Error publishing Pub/Sub message: " + e.getMessage(), e);
      responseMessage = "Error publishing Pub/Sub message; see logs for more info.";
    }

    responseWriter.write(responseMessage);
  }
}

Node.js

const {PubSub} = require('@google-cloud/pubsub');

// Instantiates a client
const pubsub = new PubSub();

/**
 * Publishes a message to a Cloud Pub/Sub Topic.
 *
 * @param {object} req Cloud Function request context.
 * @param {object} req.body The request body.
 * @param {string} req.body.topic Topic name on which to publish.
 * @param {string} req.body.message Message to publish.
 * @param {object} res Cloud Function response context.
 */
exports.publish = async (req, res) => {
  if (!req.body.topic || !req.body.message) {
    res
      .status(400)
      .send(
        'Missing parameter(s); include "topic" and "message" properties in your request.'
      );
    return;
  }

  console.log(`Publishing message to topic ${req.body.topic}`);

  // References an existing topic
  const topic = pubsub.topic(req.body.topic);

  const messageObject = {
    data: {
      message: req.body.message,
    },
  };
  const messageBuffer = Buffer.from(JSON.stringify(messageObject), 'utf8');

  // Publishes a message
  try {
    topic.publishMessage(messageBuffer);
    res.status(200).send('Message published.');
  } catch (err) {
    console.error(err);
    res.status(500).send(err);
    return Promise.reject(err);
  }
};

Python

import base64
import json
import os

from google.cloud import pubsub_v1


# TODO(developer): set this environment variable
PROJECT_ID = os.getenv("GOOGLE_CLOUD_PROJECT")


# Instantiates a Pub/Sub client
publisher = pubsub_v1.PublisherClient()


# Publishes a message to a Cloud Pub/Sub topic.
def publish(request):
    request_json = request.get_json(silent=True)

    topic_name = request_json.get("topic")
    message = request_json.get("message")

    if not topic_name or not message:
        return ('Missing "topic" and/or "message" parameter.', 400)

    print(f"Publishing message to topic {topic_name}")

    # References an existing topic
    topic_path = publisher.topic_path(PROJECT_ID, topic_name)

    message_json = json.dumps(
        {
            "data": {"message": message},
        }
    )
    message_bytes = message_json.encode("utf-8")

    # Publishes a message
    try:
        publish_future = publisher.publish(topic_path, data=message_bytes)
        publish_future.result()  # Verify the publish succeeded
        return "Message published."
    except Exception as e:
        print(e)
        return (e, 500)

Étape suivante

Pour rechercher et filtrer des exemples de code pour d'autres Google Cloud produits, consultez l'explorateur d'exemplesGoogle Cloud .