NestJS Enterprise Backend APIs · レッスン

RabbitMQの統合

NestJSマイクロサービス間の堅牢な非同期通信を実現するメッセージブローカーとしてRabbitMQを統合します。

「RabbitMQの統合」はCoddyKit上の無料NestJS Enterprise Backend APIsレッスンです。これはレッスン2/3です。下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。これはNestJS Enterprise Backend APIs学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 NestJS Enterprise Backend APIsコースには全3レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

Meet RabbitMQ

Welcome to integrating RabbitMQ with NestJS! RabbitMQ is a popular message broker that helps different parts of your application communicate reliably.

Think of it as a post office for your application's messages. Services can drop off messages, and other services can pick them up when they're ready.

Why Use Message Queues?

In a microservices architecture, direct communication can lead to tight coupling. Message queues solve this by enabling asynchronous communication.

Decoupling: Services don't need to know about each other directly.
Resilience: If a service is down, messages wait in the queue.
Scalability: Easily add more consumers to process messages faster.
Load Balancing: Distribute tasks among multiple workers.

Key RabbitMQ Concepts

Let's quickly define the essential terms:

Producer: An application that sends messages to the queue.
Consumer: An application that receives and processes messages from the queue.
Queue: A buffer that stores messages. Messages wait here until a consumer picks them up.
Message: The data payload sent by a producer and consumed by a consumer.

NestJS & RabbitMQ Transporter

NestJS provides excellent support for microservices using various transporters. RabbitMQ is one such transporter, enabling robust inter-service communication.

You'll configure your NestJS applications as either a client (producer) that sends messages, or a microservice (consumer) that listens for and processes messages.

Running RabbitMQ Locally

Before integrating, you need a running RabbitMQ instance. The easiest way for local development is using Docker:

docker run -d --hostname my-rabbit --name some-rabbit -p 5672:5672 -p 15672:15672 rabbitmq:3-management

This command starts a RabbitMQ server on port 5672 (for AMQP) and 15672 (for management UI).

Producer App Entry Point

This main.ts file is the entry point for a NestJS application configured to act as a producer. It starts an HTTP server that can trigger message sending.

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  await app.listen(3000);
  console.log('Producer HTTP Gateway running on port 3000');
}
bootstrap();

Producer Client Configuration

To send messages, the producer NestJS app needs a client proxy. Configure the ClientsModule in your AppModule to define this RabbitMQ client.

The name ('MESSAGE_SERVICE') is a token used for dependency injection.

import { Module } from '@nestjs/common';
import { ClientsModule, Transport } from '@nestjs/microservices';
import { AppController } from './app.controller';

@Module({
  imports: [
    ClientsModule.register([
      {
        name: 'MESSAGE_SERVICE',
        transport: Transport.RMQ,
        options: {
          urls: ['amqp://localhost:5672'],
          queue: 'my_nest_queue',
          queueOptions: { durable: false },
        },
      },
    ]),
  ],
  controllers: [AppController],
})
export class AppModule {}

Sending an Event Message

Now, inject the configured ClientProxy into a controller or service. Use client.emit() to send an event message to the RabbitMQ queue.

emit() is used for event-based communication where no response is expected.

import { Controller, Get, Inject } from '@nestjs/common';
import { ClientProxy } from '@nestjs/microservices';

@Controller('events')
export class AppController {
  constructor(@Inject('MESSAGE_SERVICE') private client: ClientProxy) {}

  @Get('publish')
  async publishEvent() {
    const payload = { id: 101, text: 'Hello from producer!' };
    this.client.emit('message_event', payload);
    return 'Event sent to RabbitMQ!';
  }
}

Consumer Microservice Entry

This main.ts bootstraps a NestJS application as a microservice. It listens for messages from the specified RabbitMQ queue, acting as a consumer.

Notice NestFactory.createMicroservice instead of create.

import { NestFactory } from '@nestjs/core';
import { MicroserviceOptions, Transport } from '@nestjs/microservices';
import { AppModule } from './app.module';

async function bootstrap() {
  const app = await NestFactory.createMicroservice<MicroserviceOptions>(
    AppModule,
    {
      transport: Transport.RMQ,
      options: {
        urls: ['amqp://localhost:5672'],
        queue: 'my_nest_queue',
        queueOptions: { durable: false },
      },
    },
  );
  await app.listen();
  console.log('Consumer Microservice is listening on RabbitMQ queue!');
}
bootstrap();

Processing Incoming Messages

In your consumer service, use the @MessagePattern() decorator to define methods that will handle specific messages from the queue.

It's crucial to acknowledge (ack()) messages to inform RabbitMQ they've been processed successfully.

import { Injectable } from '@nestjs/common';
import { MessagePattern, RmqContext, Ctx, Payload } from '@nestjs/microservices';

@Injectable()
export class AppService {
  @MessagePattern('message_event')
  handleMessage(@Payload() data: any, @Ctx() context: RmqContext) {
    console.log('Received message:', data);
    const channel = context.getChannelRef();
    const originalMsg = context.getMessage();
    channel.ack(originalMsg);
    return { status: 'success', data: data };
  }
}

RabbitMQ Quick Check

You've learned how to set up producers and consumers. Let's test your understanding!

Recap: RMQ Integration

You've successfully learned the basics of integrating RabbitMQ with NestJS!

RabbitMQ enables asynchronous, decoupled communication.
NestJS uses transporters like RabbitMQ for microservices.
You configured a NestJS app as a producer (client) to send messages using client.emit().
You configured another NestJS app as a consumer (microservice) to receive messages using @MessagePattern().
Remember to acknowledge messages for reliability.

This is a powerful pattern for building scalable and robust microservices!

よくある質問

「RabbitMQの統合」レッスンは無料ですか？

はい。「RabbitMQの統合」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、NestJS Enterprise Backend APIsコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 NestJS Enterprise Backend APIsコースには全3レッスンが含まれています。

「RabbitMQの統合」で何を学びますか？

NestJSマイクロサービス間の堅牢な非同期通信を実現するメッセージブローカーとしてRabbitMQを統合します。ブラウザで直接実行するハンズオンコードでNestJS Enterprise Backend APIsを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。

NestJS Enterprise Backend APIsを始めるのに経験は必要ですか？

事前経験は必要ありません。CoddyKitのNestJS Enterprise Backend APIsは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。これはレッスン2/3です。

「RabbitMQの統合」レッスンにはどのくらい時間がかかりますか？

ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。

このNestJS Enterprise Backend APIsレッスンでコードを書いて実行できますか？

はい。すべてのNestJS Enterprise Backend APIsレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。

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