Pubblicare messaggi in un argomento con uno schema

gcloud

1. In the Trusted Cloud console, activate Cloud Shell.

   Activate Cloud Shell

   At the bottom of the Trusted Cloud console, a Cloud Shell session starts and displays a command-line prompt. Cloud Shell is a shell environment with the Google Cloud CLI already installed and with values already set for your current project. It can take a few seconds for the session to initialize.

2. Pubblica un messaggio di esempio utilizzando il comando gcloud pubsub topics publish.

   gcloud pubsub topics publish TOPIC_ID \
       --message=MESSAGE
   

   Sostituisci quanto segue:

• TOPIC_ID: il nome dell'argomento che hai già creato.

• MESSAGE: Messaggio pubblicato nell'argomento. Un messaggio di esempio potrebbe essere {"name": "Alaska", "post_abbr": "AK"}.

C++

Prima di provare questo esempio, segui le istruzioni di configurazione di C++ nella guida rapida all'utilizzo delle librerie client. Per ulteriori informazioni, consulta la documentazione di riferimento dell'API Pub/Sub C++.

Avro

namespace pubsub = ::google::cloud::pubsub;
using ::google::cloud::future;
using ::google::cloud::StatusOr;
[](pubsub::Publisher publisher) {
  auto constexpr kNewYork =
      R"js({ "name": "New York", "post_abbr": "NY" })js";
  auto constexpr kPennsylvania =
      R"js({ "name": "Pennsylvania", "post_abbr": "PA" })js";
  std::vector<future<void>> done;
  auto handler = [](future<StatusOr<std::string>> f) {
    auto id = f.get();
    if (!id) throw std::move(id).status();
  };
  for (auto const* data : {kNewYork, kPennsylvania}) {
    done.push_back(
        publisher.Publish(pubsub::MessageBuilder{}.SetData(data).Build())
            .then(handler));
  }
  // Block until all messages are published.
  for (auto& d : done) d.get();
}

Proto

namespace pubsub = ::google::cloud::pubsub;
using ::google::cloud::future;
using ::google::cloud::StatusOr;
[](pubsub::Publisher publisher) {
  std::vector<std::pair<std::string, std::string>> states{
      {"New York", "NY"},
      {"Pennsylvania", "PA"},
  };
  std::vector<future<void>> done;
  auto handler = [](future<StatusOr<std::string>> f) {
    auto id = f.get();
    if (!id) throw std::move(id).status();
  };
  for (auto& data : states) {
    google::cloud::pubsub::samples::State state;
    state.set_name(data.first);
    state.set_post_abbr(data.second);
    done.push_back(publisher
                       .Publish(pubsub::MessageBuilder{}
                                    .SetData(state.SerializeAsString())
                                    .Build())
                       .then(handler));
  }
  // Block until all messages are published.
  for (auto& d : done) d.get();
}

C#

Prima di provare questo esempio, segui le istruzioni di configurazione di C# nella guida rapida all'utilizzo delle librerie client. Per ulteriori informazioni, consulta la documentazione di riferimento dell'API Pub/Sub C#.

Avro

using Avro.IO;
using Avro.Specific;
using Google.Cloud.PubSub.V1;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

public class PublishAvroMessagesAsyncSample
{
    public async Task<int> PublishAvroMessagesAsync(string projectId, string topicId, IEnumerable<AvroUtilities.State> messageStates)
    {
        TopicName topicName = TopicName.FromProjectTopic(projectId, topicId);
        PublisherClient publisher = await PublisherClient.CreateAsync(topicName);

        PublisherServiceApiClient publishApi = PublisherServiceApiClient.Create();
        var topic = publishApi.GetTopic(topicName);

        int publishedMessageCount = 0;
        var publishTasks = messageStates.Select(async state =>
        {

            try
            {
                string messageId = null;
                switch (topic.SchemaSettings.Encoding)
                {
                    case Encoding.Binary:
                        using (var ms = new MemoryStream())
                        {
                            var encoder = new BinaryEncoder(ms);
                            var writer = new SpecificDefaultWriter(state.Schema);
                            writer.Write(state, encoder);
                            messageId = await publisher.PublishAsync(ms.ToArray());
                        }
                        break;
                    case Encoding.Json:
                        var jsonMessage = AvroUtilities.StateUtils.StateToJsonString(state);
                        messageId = await publisher.PublishAsync(jsonMessage);
                        break;
                }
                Console.WriteLine($"Published message {messageId}");
                Interlocked.Increment(ref publishedMessageCount);
            }
            catch (Exception exception)
            {
                Console.WriteLine($"An error occurred when publishing message {state}: {exception.Message}");
            }
        });
        await Task.WhenAll(publishTasks);
        return publishedMessageCount;
    }
}

Proto

using Google.Cloud.PubSub.V1;
using Google.Protobuf;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

public class PublishProtoMessagesAsyncSample
{
    public async Task<int> PublishProtoMessagesAsync(string projectId, string topicId, IEnumerable<Utilities.State> messageStates)
    {
        TopicName topicName = TopicName.FromProjectTopic(projectId, topicId);
        PublisherClient publisher = await PublisherClient.CreateAsync(topicName);

        PublisherServiceApiClient publishApi = PublisherServiceApiClient.Create();
        var topic = publishApi.GetTopic(topicName);

        int publishedMessageCount = 0;
        var publishTasks = messageStates.Select(async state =>
        {
            try
            {
                string messageId = null;
                switch (topic.SchemaSettings.Encoding)
                {
                    case Encoding.Binary:
                        var binaryMessage = state.ToByteString();
                        messageId = await publisher.PublishAsync(binaryMessage);
                        break;
                    case Encoding.Json:
                        var jsonMessage = JsonFormatter.Default.Format(state);
                        messageId = await publisher.PublishAsync(jsonMessage);
                        break;
                }
                Console.WriteLine($"Published message {messageId}");
                Interlocked.Increment(ref publishedMessageCount);
            }
            catch (Exception exception)
            {
                Console.WriteLine($"An error occurred when publishing message {state}: {exception.Message}");
            }
        });
        await Task.WhenAll(publishTasks);
        return publishedMessageCount;
    }
}

Vai

L'esempio seguente utilizza la versione principale della libreria client Go Pub/Sub (v2). Se utilizzi ancora la libreria v1, consulta la guida alla migrazione alla v2. Per visualizzare un elenco di esempi di codice della versione 1, consulta gli esempi di codice ritirati.

Prima di provare questo esempio, segui le istruzioni di configurazione di Go nella guida rapida all'utilizzo delle librerie client. Per saperne di più, consulta la documentazione di riferimento dell'API Pub/Sub Go.

Avro

import (
	"context"
	"fmt"
	"io"
	"os"

	"cloud.google.com/go/pubsub/v2"
	"cloud.google.com/go/pubsub/v2/apiv1/pubsubpb"
	"github.com/linkedin/goavro/v2"
)

func publishAvroRecords(w io.Writer, projectID, topicID, avscFile string) error {
	// projectID := "my-project-id"
	// topicID := "my-topic"
	// avscFile = "path/to/an/avro/schema/file(.avsc)/formatted/in/json"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %w", err)
	}

	avroSource, err := os.ReadFile(avscFile)
	if err != nil {
		return fmt.Errorf("os.ReadFile err: %w", err)
	}
	codec, err := goavro.NewCodec(string(avroSource))
	if err != nil {
		return fmt.Errorf("goavro.NewCodec err: %w", err)
	}
	record := map[string]interface{}{"name": "Alaska", "post_abbr": "AK"}

	// Get the topic encoding type.
	req := &pubsubpb.GetTopicRequest{
		Topic: fmt.Sprintf("projects/%s/topics/%s", projectID, topicID),
	}
	t, err := client.TopicAdminClient.GetTopic(ctx, req)
	if err != nil {
		return fmt.Errorf("got err in GetTopic: %w", err)
	}
	encoding := t.SchemaSettings.Encoding

	var msg []byte
	switch encoding {
	case pubsubpb.Encoding_BINARY:
		msg, err = codec.BinaryFromNative(nil, record)
		if err != nil {
			return fmt.Errorf("codec.BinaryFromNative err: %w", err)
		}
	case pubsubpb.Encoding_JSON:
		msg, err = codec.TextualFromNative(nil, record)
		if err != nil {
			return fmt.Errorf("codec.TextualFromNative err: %w", err)
		}
	default:
		return fmt.Errorf("invalid encoding: %v", encoding)
	}

	// client.Publisher can be passed a topic ID (e.g. "my-topic") or
	// a fully qualified name (e.g. "projects/my-project/topics/my-topic").
	// If a topic ID is provided, the project ID from the client is used.
	publisher := client.Publisher(topicID)
	result := publisher.Publish(ctx, &pubsub.Message{
		Data: msg,
	})
	_, err = result.Get(ctx)
	if err != nil {
		return fmt.Errorf("result.Get: %w", err)
	}
	fmt.Fprintf(w, "Published avro record: %s\n", string(msg))
	return nil
}

Proto

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/pubsub/v2"
	"cloud.google.com/go/pubsub/v2/apiv1/pubsubpb"
	statepb "github.com/GoogleCloudPlatform/golang-samples/internal/pubsub/schemas"
	"google.golang.org/protobuf/encoding/protojson"
	"google.golang.org/protobuf/proto"
)

func publishProtoMessages(w io.Writer, projectID, topicID string) error {
	// projectID := "my-project-id"
	// topicID := "my-topic"
	ctx := context.Background()
	client, err := pubsub.NewClient(ctx, projectID)
	if err != nil {
		return fmt.Errorf("pubsub.NewClient: %w", err)
	}

	state := &statepb.State{
		Name:     "Alaska",
		PostAbbr: "AK",
	}

	// Get the topic encoding type.
	req := &pubsubpb.GetTopicRequest{
		Topic: fmt.Sprintf("projects/%s/topics/%s", projectID, topicID),
	}
	t, err := client.TopicAdminClient.GetTopic(ctx, req)
	if err != nil {
		return fmt.Errorf("got err in GetTopic: %w", err)
	}
	encoding := t.SchemaSettings.Encoding

	var msg []byte
	switch encoding {
	case pubsubpb.Encoding_BINARY:
		msg, err = proto.Marshal(state)
		if err != nil {
			return fmt.Errorf("proto.Marshal err: %w", err)
		}
	case pubsubpb.Encoding_JSON:
		msg, err = protojson.Marshal(state)
		if err != nil {
			return fmt.Errorf("protojson.Marshal err: %w", err)
		}
	default:
		return fmt.Errorf("invalid encoding: %v", encoding)
	}

	// client.Publisher can be passed a topic ID (e.g. "my-topic") or
	// a fully qualified name (e.g. "projects/my-project/topics/my-topic").
	// If a topic ID is provided, the project ID from the client is used.
	publisher := client.Publisher(topicID)
	result := publisher.Publish(ctx, &pubsub.Message{
		Data: msg,
	})
	_, err = result.Get(ctx)
	if err != nil {
		return fmt.Errorf("result.Get: %w", err)
	}
	fmt.Fprintf(w, "Published proto message with %#v encoding: %s\n", encoding, string(msg))
	return nil
}

Java

Prima di provare questo esempio, segui le istruzioni di configurazione di Java nella guida rapida all'utilizzo delle librerie client. Per saperne di più, consulta la documentazione di riferimento dell'API Java di Pub/Sub.

Avro

import com.google.api.core.ApiFuture;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.cloud.pubsub.v1.TopicAdminClient;
import com.google.protobuf.ByteString;
import com.google.pubsub.v1.Encoding;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.TopicName;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import org.apache.avro.io.Encoder;
import org.apache.avro.io.EncoderFactory;
import utilities.State;

public class PublishAvroRecordsExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    // Use a topic created with an Avro schema.
    String topicId = "your-topic-id";

    publishAvroRecordsExample(projectId, topicId);
  }

  public static void publishAvroRecordsExample(String projectId, String topicId)
      throws IOException, ExecutionException, InterruptedException {

    Encoding encoding = null;

    TopicName topicName = TopicName.of(projectId, topicId);

    // Get the topic encoding type.
    try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
      encoding = topicAdminClient.getTopic(topicName).getSchemaSettings().getEncoding();
    }

    // Instantiate an avro-tools-generated class defined in `us-states.avsc`.
    State state = State.newBuilder().setName("Alaska").setPostAbbr("AK").build();

    Publisher publisher = null;

    block:
    try {
      publisher = Publisher.newBuilder(topicName).build();

      // Prepare to serialize the object to the output stream.
      ByteArrayOutputStream byteStream = new ByteArrayOutputStream();

      Encoder encoder = null;

      // Prepare an appropriate encoder for publishing to the topic.
      switch (encoding) {
        case BINARY:
          System.out.println("Preparing a BINARY encoder...");
          encoder = EncoderFactory.get().directBinaryEncoder(byteStream, /* reuse= */ null);
          break;

        case JSON:
          System.out.println("Preparing a JSON encoder...");
          encoder = EncoderFactory.get().jsonEncoder(State.getClassSchema(), byteStream);
          break;

        default:
          break block;
      }

      // Encode the object and write it to the output stream.
      state.customEncode(encoder);
      encoder.flush();

      // Publish the encoded object as a Pub/Sub message.
      ByteString data = ByteString.copyFrom(byteStream.toByteArray());
      PubsubMessage message = PubsubMessage.newBuilder().setData(data).build();
      System.out.println("Publishing message: " + message);

      ApiFuture<String> future = publisher.publish(message);
      System.out.println("Published message ID: " + future.get());

    } finally {
      if (publisher != null) {
        publisher.shutdown();
        publisher.awaitTermination(1, TimeUnit.MINUTES);
      }
    }
  }
}

Proto

import com.google.api.core.ApiFuture;
import com.google.cloud.pubsub.v1.Publisher;
import com.google.cloud.pubsub.v1.TopicAdminClient;
import com.google.protobuf.ByteString;
import com.google.protobuf.util.JsonFormat;
import com.google.pubsub.v1.Encoding;
import com.google.pubsub.v1.PubsubMessage;
import com.google.pubsub.v1.TopicName;
import java.io.IOException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import utilities.StateProto.State;

public class PublishProtobufMessagesExample {

  public static void main(String... args) throws Exception {
    // TODO(developer): Replace these variables before running the sample.
    String projectId = "your-project-id";
    // Use a topic created with a proto schema.
    String topicId = "your-topic-id";

    publishProtobufMessagesExample(projectId, topicId);
  }

  public static void publishProtobufMessagesExample(String projectId, String topicId)
      throws IOException, ExecutionException, InterruptedException {

    Encoding encoding = null;

    TopicName topicName = TopicName.of(projectId, topicId);

    // Get the topic encoding type.
    try (TopicAdminClient topicAdminClient = TopicAdminClient.create()) {
      encoding = topicAdminClient.getTopic(topicName).getSchemaSettings().getEncoding();
    }

    Publisher publisher = null;

    // Instantiate a protoc-generated class defined in `us-states.proto`.
    State state = State.newBuilder().setName("Alaska").setPostAbbr("AK").build();

    block:
    try {
      publisher = Publisher.newBuilder(topicName).build();

      PubsubMessage.Builder message = PubsubMessage.newBuilder();

      // Prepare an appropriately formatted message based on topic encoding.
      switch (encoding) {
        case BINARY:
          message.setData(state.toByteString());
          System.out.println("Publishing a BINARY-formatted message:\n" + message);
          break;

        case JSON:
          String jsonString = JsonFormat.printer().omittingInsignificantWhitespace().print(state);
          message.setData(ByteString.copyFromUtf8(jsonString));
          System.out.println("Publishing a JSON-formatted message:\n" + message);
          break;

        default:
          break block;
      }

      // Publish the message.
      ApiFuture<String> future = publisher.publish(message.build());
      System.out.println("Published message ID: " + future.get());

    } finally {
      if (publisher != null) {
        publisher.shutdown();
        publisher.awaitTermination(1, TimeUnit.MINUTES);
      }
    }
  }
}

Node.js

Prima di provare questo esempio, segui le istruzioni di configurazione di Node.js nella Guida rapida all'utilizzo delle librerie client. Per saperne di più, consulta la documentazione di riferimento dell'API Pub/Sub Node.js.

Avro

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';

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

// And the Apache Avro library
const avro = require('avro-js');
const fs = require('fs');

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

async function publishAvroRecords(topicNameOrId) {
  // Cache topic objects (publishers) and reuse them.
  const topic = pubSubClient.topic(topicNameOrId);

  // Get the topic metadata to learn about its schema encoding.
  const [topicMetadata] = await topic.getMetadata();
  const topicSchemaMetadata = topicMetadata.schemaSettings;

  if (!topicSchemaMetadata) {
    console.log(`Topic ${topicNameOrId} doesn't seem to have a schema.`);
    return;
  }
  const schemaEncoding = topicSchemaMetadata.encoding;

  // Make an encoder using the official avro-js library.
  const definition = fs
    .readFileSync('system-test/fixtures/provinces.avsc')
    .toString();
  const type = avro.parse(definition);

  // Encode the message.
  const province = {
    name: 'Ontario',
    post_abbr: 'ON',
  };
  let dataBuffer;
  switch (schemaEncoding) {
    case Encodings.Binary:
      dataBuffer = type.toBuffer(province);
      break;
    case Encodings.Json:
      dataBuffer = Buffer.from(type.toString(province));
      break;
    default:
      console.log(`Unknown schema encoding: ${schemaEncoding}`);
      break;
  }
  if (!dataBuffer) {
    console.log(`Invalid encoding ${schemaEncoding} on the topic.`);
    return;
  }

  const messageId = await topic.publish(dataBuffer);
  console.log(`Avro record ${messageId} published.`);
}

Buffer di protocollo

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';

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

// And the protobufjs library
const protobuf = require('protobufjs');

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

async function publishProtobufMessages(topicNameOrId) {
  // Cache topic objects (publishers) and reuse them.
  const topic = pubSubClient.topic(topicNameOrId);

  // Get the topic metadata to learn about its schema.
  const [topicMetadata] = await topic.getMetadata();
  const topicSchemaMetadata = topicMetadata.schemaSettings;

  if (!topicSchemaMetadata) {
    console.log(`Topic ${topicNameOrId} doesn't seem to have a schema.`);
    return;
  }
  const schemaEncoding = topicSchemaMetadata.encoding;

  // Encode the message.
  const province = {
    name: 'Ontario',
    postAbbr: 'ON',
  };

  // Make an encoder using the protobufjs library.
  //
  // Since we're providing the test message for a specific schema here, we'll
  // also code in the path to a sample proto definition.
  const root = await protobuf.load('system-test/fixtures/provinces.proto');
  const Province = root.lookupType('utilities.Province');
  const message = Province.create(province);

  let dataBuffer;
  switch (schemaEncoding) {
    case Encodings.Binary:
      dataBuffer = Buffer.from(Province.encode(message).finish());
      break;
    case Encodings.Json:
      dataBuffer = Buffer.from(JSON.stringify(message.toJSON()));
      break;
    default:
      console.log(`Unknown schema encoding: ${schemaEncoding}`);
      break;
  }
  if (!dataBuffer) {
    console.log(`Invalid encoding ${schemaEncoding} on the topic.`);
    return;
  }

  const messageId = await topic.publishMessage({data: dataBuffer});
  console.log(`Protobuf message ${messageId} published.`);
}

Node.js

Prima di provare questo esempio, segui le istruzioni di configurazione di Node.js nella Guida rapida all'utilizzo delle librerie client. Per saperne di più, consulta la documentazione di riferimento dell'API Pub/Sub Node.js.

Avro

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';

// Imports the Google Cloud client library
import {PubSub, Encodings} from '@google-cloud/pubsub';

// And the Apache Avro library
import * as avro from 'avro-js';
import * as fs from 'fs';

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

interface ProvinceObject {
  name: string;
  post_abbr: string;
}

async function publishAvroRecords(topicNameOrId: string) {
  // Cache topic objects (publishers) and reuse them.
  const topic = pubSubClient.topic(topicNameOrId);

  // Get the topic metadata to learn about its schema encoding.
  const [topicMetadata] = await topic.getMetadata();
  const topicSchemaMetadata = topicMetadata.schemaSettings;

  if (!topicSchemaMetadata) {
    console.log(`Topic ${topicNameOrId} doesn't seem to have a schema.`);
    return;
  }
  const schemaEncoding = topicSchemaMetadata.encoding;

  // Make an encoder using the official avro-js library.
  const definition = fs
    .readFileSync('system-test/fixtures/provinces.avsc')
    .toString();
  const type = avro.parse(definition);

  // Encode the message.
  const province: ProvinceObject = {
    name: 'Ontario',
    post_abbr: 'ON',
  };
  let dataBuffer: Buffer | undefined;
  switch (schemaEncoding) {
    case Encodings.Binary:
      dataBuffer = type.toBuffer(province);
      break;
    case Encodings.Json:
      dataBuffer = Buffer.from(type.toString(province));
      break;
    default:
      console.log(`Unknown schema encoding: ${schemaEncoding}`);
      break;
  }
  if (!dataBuffer) {
    console.log(`Invalid encoding ${schemaEncoding} on the topic.`);
    return;
  }

  const messageId = await topic.publish(dataBuffer);
  console.log(`Avro record ${messageId} published.`);
}

Buffer di protocollo

/**
 * TODO(developer): Uncomment this variable before running the sample.
 */
// const topicNameOrId = 'YOUR_TOPIC_NAME_OR_ID';

// Imports the Google Cloud client library
import {PubSub, Encodings} from '@google-cloud/pubsub';

// And the protobufjs library
import * as protobuf from 'protobufjs';

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

interface ProvinceObject {
  name: string;
  postAbbr: string;
}

async function publishProtobufMessages(topicNameOrId: string) {
  // Cache topic objects (publishers) and reuse them.
  const topic = pubSubClient.topic(topicNameOrId);

  // Get the topic metadata to learn about its schema.
  const [topicMetadata] = await topic.getMetadata();
  const topicSchemaMetadata = topicMetadata.schemaSettings;

  if (!topicSchemaMetadata) {
    console.log(`Topic ${topicNameOrId} doesn't seem to have a schema.`);
    return;
  }
  const schemaEncoding = topicSchemaMetadata.encoding;

  // Encode the message.
  const province: ProvinceObject = {
    name: 'Ontario',
    postAbbr: 'ON',
  };

  // Make an encoder using the protobufjs library.
  //
  // Since we're providing the test message for a specific schema here, we'll
  // also code in the path to a sample proto definition.
  const root = await protobuf.load('system-test/fixtures/provinces.proto');
  const Province = root.lookupType('utilities.Province');
  const message = Province.create(province);

  let dataBuffer: Buffer | undefined;
  switch (schemaEncoding) {
    case Encodings.Binary:
      dataBuffer = Buffer.from(Province.encode(message).finish());
      break;
    case Encodings.Json:
      dataBuffer = Buffer.from(JSON.stringify(message.toJSON()));
      break;
    default:
      console.log(`Unknown schema encoding: ${schemaEncoding}`);
      break;
  }
  if (!dataBuffer) {
    console.log(`Invalid encoding ${schemaEncoding} on the topic.`);
    return;
  }

  const messageId = await topic.publishMessage({data: dataBuffer});
  console.log(`Protobuf message ${messageId} published.`);
}

PHP

Prima di provare questo esempio, segui le istruzioni di configurazione di PHP nella guida rapida all'utilizzo delle librerie client. Per saperne di più, consulta la documentazione di riferimento dell'API Pub/Sub PHP.

Avro

use Google\Cloud\PubSub\PubSubClient;
use Google\Cloud\PubSub\V1\Encoding;

use AvroStringIO;
use AvroSchema;
use AvroIODatumWriter;
use AvroIOBinaryEncoder;

/**
 * Publish a message using an AVRO schema.
 *
 * This sample uses `wikimedia/avro` for AVRO encoding.
 *
 * @param string $projectId
 * @param string $topicId
 * @param string $definitionFile
 */
function publish_avro_records($projectId, $topicId, $definitionFile)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);

    $definition = (string) file_get_contents($definitionFile);

    $messageData = [
        'name' => 'Alaska',
        'post_abbr' => 'AK',
    ];

    $topic = $pubsub->topic($topicId);

    // get the encoding type.
    $topicInfo = $topic->info();
    $encoding = '';
    if (isset($topicInfo['schemaSettings']['encoding'])) {
        $encoding = $topicInfo['schemaSettings']['encoding'];
    }

    // if encoding is not set, we can't continue.
    if ($encoding === '') {
        printf('Topic %s does not have schema enabled', $topicId);
        return;
    }

    // If you are using gRPC, encoding may be an integer corresponding to an
    // enum value on Google\Cloud\PubSub\V1\Encoding.
    if (!is_string($encoding)) {
        $encoding = Encoding::name($encoding);
    }

    $encodedMessageData = '';
    if ($encoding == 'BINARY') {
        // encode as AVRO binary.
        $io = new AvroStringIO();
        $schema = AvroSchema::parse($definition);
        $writer = new AvroIODatumWriter($schema);
        $encoder = new AvroIOBinaryEncoder($io);
        $writer->write($messageData, $encoder);

        $encodedMessageData = $io->string();
    } else {
        // encode as JSON.
        $encodedMessageData = json_encode($messageData);
    }

    $topic->publish(['data' => $encodedMessageData]);

    printf('Published message with %s encoding', $encoding);
}

Buffer di protocollo

use Google\Cloud\PubSub\PubSubClient;
use Google\Cloud\PubSub\V1\Encoding;

use Utilities\StateProto;

/**
 * Publish a message using a protocol buffer schema.
 *
 * Relies on a proto message of the following form:
 * ```
 * syntax = "proto3";
 *
 * package utilities;
 *
 * message StateProto {
 *   string name = 1;
 *   string post_abbr = 2;
 * }
 * ```
 *
 * @param string $projectId
 * @param string $topicId
 * @return void
 */
function publish_proto_messages($projectId, $topicId)
{
    $pubsub = new PubSubClient([
        'projectId' => $projectId,
    ]);

    $messageData = new StateProto([
        'name' => 'Alaska',
        'post_abbr' => 'AK',
    ]);

    $topic = $pubsub->topic($topicId);

    // get the encoding type.
    $topicInfo = $topic->info();
    $encoding = '';
    if (isset($topicInfo['schemaSettings']['encoding'])) {
        $encoding = $topicInfo['schemaSettings']['encoding'];
    }

    // if encoding is not set, we can't continue.
    if ($encoding === '') {
        printf('Topic %s does not have schema enabled', $topicId);
        return;
    }

    // If you are using gRPC, encoding may be an integer corresponding to an
    // enum value on Google\Cloud\PubSub\V1\Encoding.
    if (!is_string($encoding)) {
        $encoding = Encoding::name($encoding);
    }

    $encodedMessageData = '';
    if ($encoding == 'BINARY') {
        // encode as protobuf binary.
        $encodedMessageData = $messageData->serializeToString();
    } else {
        // encode as JSON.
        $encodedMessageData = $messageData->serializeToJsonString();
    }

    $topic->publish(['data' => $encodedMessageData]);

    printf('Published message with %s encoding', $encoding);
}

Python

Prima di provare questo esempio, segui le istruzioni di configurazione di Python nella guida rapida all'utilizzo delle librerie client. Per saperne di più, consulta la documentazione di riferimento dell'API Pub/Sub Python.

Avro

from avro.io import BinaryEncoder, DatumWriter
import avro.schema as schema
import io
import json
from google.api_core.exceptions import NotFound
from google.cloud.pubsub import PublisherClient
from google.pubsub_v1.types import Encoding

# TODO(developer): Replace these variables before running the sample.
# project_id = "your-project-id"
# topic_id = "your-topic-id"
# avsc_file = "path/to/an/avro/schema/file/(.avsc)/formatted/in/json"

publisher_client = PublisherClient()
topic_path = publisher_client.topic_path(project_id, topic_id)

# Prepare to write Avro records to the binary output stream.
with open(avsc_file, "rb") as file:
    avro_schema = schema.parse(file.read())
writer = DatumWriter(avro_schema)
bout = io.BytesIO()

# Prepare some data using a Python dictionary that matches the Avro schema
record = {"name": "Alaska", "post_abbr": "AK"}

try:
    # Get the topic encoding type.
    topic = publisher_client.get_topic(request={"topic": topic_path})
    encoding = topic.schema_settings.encoding

    # Encode the data according to the message serialization type.
    if encoding == Encoding.BINARY:
        encoder = BinaryEncoder(bout)
        writer.write(record, encoder)
        data = bout.getvalue()
        print(f"Preparing a binary-encoded message:\n{data.decode()}")
    elif encoding == Encoding.JSON:
        data_str = json.dumps(record)
        print(f"Preparing a JSON-encoded message:\n{data_str}")
        data = data_str.encode("utf-8")
    else:
        print(f"No encoding specified in {topic_path}. Abort.")
        exit(0)

    future = publisher_client.publish(topic_path, data)
    print(f"Published message ID: {future.result()}")

except NotFound:
    print(f"{topic_id} not found.")

Buffer di protocollo

from google.api_core.exceptions import NotFound
from google.cloud.pubsub import PublisherClient
from google.protobuf.json_format import MessageToJson
from google.pubsub_v1.types import Encoding

from utilities import us_states_pb2  # type: ignore

# TODO(developer): Replace these variables before running the sample.
# project_id = "your-project-id"
# topic_id = "your-topic-id"

publisher_client = PublisherClient()
topic_path = publisher_client.topic_path(project_id, topic_id)

try:
    # Get the topic encoding type.
    topic = publisher_client.get_topic(request={"topic": topic_path})
    encoding = topic.schema_settings.encoding

    # Instantiate a protoc-generated class defined in `us-states.proto`.
    state = us_states_pb2.StateProto()
    state.name = "Alaska"
    state.post_abbr = "AK"

    # Encode the data according to the message serialization type.
    if encoding == Encoding.BINARY:
        data = state.SerializeToString()
        print(f"Preparing a binary-encoded message:\n{data}")
    elif encoding == Encoding.JSON:
        json_object = MessageToJson(state)
        data = str(json_object).encode("utf-8")
        print(f"Preparing a JSON-encoded message:\n{data}")
    else:
        print(f"No encoding specified in {topic_path}. Abort.")
        exit(0)

    future = publisher_client.publish(topic_path, data)
    print(f"Published message ID: {future.result()}")

except NotFound:
    print(f"{topic_id} not found.")

Ruby

Il seguente esempio utilizza la libreria client Ruby Pub/Sub v3. Se utilizzi ancora la libreria v2, consulta la guida alla migrazione alla v3. Per visualizzare un elenco di esempi di codice Ruby v2, consulta gli esempi di codice ritirati.

Prima di provare questo esempio, segui le istruzioni di configurazione di Ruby nella guida rapida all'utilizzo delle librerie client. Per saperne di più, consulta la documentazione di riferimento dell'API Pub/Sub Ruby.

Avro

# topic_id = "your-topic-id"
# avsc_file = "path/to/an/avro/schema/file/(.avsc)/formatted/in/json"

pubsub = Google::Cloud::PubSub.new
topic_admin = pubsub.topic_admin
publisher = pubsub.publisher topic_id
record = { "name" => "Alaska", "post_abbr" => "AK" }

topic = topic_admin.get_topic topic: pubsub.topic_path(topic_id)
encoding = topic.schema_settings.encoding

case encoding
when :BINARY
  require "avro"
  avro_schema = Avro::Schema.parse File.read(avsc_file)
  writer = Avro::IO::DatumWriter.new avro_schema
  buffer = StringIO.new
  encoder = Avro::IO::BinaryEncoder.new buffer
  writer.write record, encoder
  publisher.publish buffer
  puts "Published binary-encoded AVRO message."
when :JSON
  require "json"
  publisher.publish record.to_json
  puts "Published JSON-encoded AVRO message."
else
  raise "No encoding specified in #{topic.name}."
end

Buffer di protocollo

# topic_id = "your-topic-id"

pubsub = Google::Cloud::PubSub.new
topic_admin = pubsub.topic_admin
publisher = pubsub.publisher topic_id
state = Utilities::StateProto.new name: "Alaska", post_abbr: "AK"

topic = topic_admin.get_topic topic: pubsub.topic_path(topic_id)
encoding = topic.schema_settings.encoding

case encoding
when :BINARY
  publisher.publish Utilities::StateProto.encode(state)
  puts "Published binary-encoded protobuf message."
when :JSON
  publisher.publish Utilities::StateProto.encode_json(state)
  puts "Published JSON-encoded protobuf message."
else
  raise "No encoding specified in #{topic.name}."
end