Memublikasikan pesan jenis skema Avro

Memublikasikan pesan yang sesuai dengan skema Avro ke topik dengan skema Avro terlampir.

Jelajahi lebih lanjut

Untuk dokumentasi mendetail yang menyertakan contoh kode ini, lihat artikel berikut:

• Memublikasikan pesan ke topik dengan skema

Contoh kode

C++

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

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

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();
}

C#

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

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

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;
    }
}

Go

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

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

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

	"cloud.google.com/go/pubsub"
	"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("ioutil.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.
	t := client.Topic(topicID)
	cfg, err := t.Config(ctx)
	if err != nil {
		return fmt.Errorf("topic.Config err: %w", err)
	}
	encoding := cfg.SchemaSettings.Encoding

	var msg []byte
	switch encoding {
	case pubsub.EncodingBinary:
		msg, err = codec.BinaryFromNative(nil, record)
		if err != nil {
			return fmt.Errorf("codec.BinaryFromNative err: %w", err)
		}
	case pubsub.EncodingJSON:
		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)
	}

	result := t.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
}

Java

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

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

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);
      }
    }
  }
}

Node.js

/**
 * 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) {
  // Get the topic metadata to learn about its schema encoding.
  const topic = pubSubClient.topic(topicNameOrId);
  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.`);
}

Node.js

/**
 * 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) {
  // Get the topic metadata to learn about its schema encoding.
  const topic = pubSubClient.topic(topicNameOrId);
  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.`);
}

PHP

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

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

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);
}

Python

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

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

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.")

Ruby

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

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

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

pubsub = Google::Cloud::Pubsub.new

topic = pubsub.topic topic_id

record = { "name" => "Alaska", "post_abbr" => "AK" }

if topic.message_encoding_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
  topic.publish buffer
  puts "Published binary-encoded AVRO message."
elsif topic.message_encoding_json?
  require "json"
  topic.publish record.to_json
  puts "Published JSON-encoded AVRO message."
else
  raise "No encoding specified in #{topic.name}."
end

Langkah selanjutnya

Untuk menelusuri dan memfilter contoh kode untuk produk Google Cloud lainnya, lihat browser contoh Google Cloud.