Supported transports include:

• RabbitMQ
• Redis
• NATS
• Amazon SQS
• Google Pub/Sub
• Azure Service Bus

Packages

Core

Official Extensions

Installation

Install the core package:

npm install @nestjstools/messaging

or

yarn add @nestjstools/messaging

Then install a transport extension if needed:

npm install @nestjstools/messaging-rabbitmq-extension

Quick Example

Below is a minimal example showing how to:

• define a message
• create a message handler
• configure the MessagingModule
• dispatch a message

1️⃣ Define a Message

export class SendMessage {
  constructor(
    public readonly content: string,
  ) {
  }
}

2️⃣ Create a Message Handler

import { Injectable } from '@nestjs/common';
import {
  MessageHandler,
  IMessageHandler,
} from '@nestjstools/messaging';
import { SendMessage } from './send-message';

@Injectable()
@MessageHandler('chat.message')
export class SendMessageHandler implements IMessageHandler<SendMessage> {

  async handle(message: SendMessage): Promise<void> {
    console.log('Received message:', message.content);
  }

}

3️⃣ Configure the Messaging Module

import { Module } from '@nestjs/common';
import { MessagingModule, InMemoryChannelConfig } from '@nestjstools/messaging';
import { SendMessageHandler } from './send-message.handler';

@Module({
  imports: [
    MessagingModule.forRoot({
      buses: [
        {
          name: 'message.bus',
          channels: ['memory'],
        },
      ],
      channels: [
        new InMemoryChannelConfig({
          name: 'memory',
        }),
      ],
      debug: true,
    }),
  ],
  providers: [SendMessageHandler],
})
export class AppModule {
}

4️⃣ Dispatch a Message

Messages can be dispatched from anywhere in your application.

Example using a controller:

import { Controller, Get } from '@nestjs/common';
import { IMessageBus, MessageBus, RoutingMessage } from '@nestjstools/messaging';
import { SendMessage } from './send-message';

@Controller()
export class AppController {

  constructor(
    @MessageBus('message.bus')
    private readonly messageBus: IMessageBus,
  ) {
  }

  @Get()
  async send(): Promise<string> {

    await this.messageBus.dispatch(
      new RoutingMessage(
        new SendMessage('Hello from NestJSTools!'),
        'chat.message',
      ),
    );

    return 'Message dispatched!';
  }
}

Architecture

High level flow of message dispatching and handling:

flowchart LR

    M[Message]
    MB[Message Bus]
    C[(Channel)]
    MW[Middleware]
    H[Message Handler]

    M -->|dispatch| MB
    MB --> C
    C --> MW
    MW --> H

Exception handling flow:

flowchart LR

    M[Message]
    MB[MessageBus]
    C[InMemoryChannel]
    MW[Middleware]
    H[MessageHandler]
    EL[ExceptionListener]

    M -->|dispatch| MB
    MB --> C
    C --> MW
    MW --> H

    H -. throws error .-> C
    MW -. throws error .-> C
    C -. notify .-> EL

Links

• Official documentation: https://docs.nestjstools.com/messaging
• Website: https://nestjstools.com
• RabbitMQ example: https://github.com/nestjstools/messaging-rabbitmq-example

🤝 Contributing

Contributions are welcome!

Please open an issue or pull request if you want to:

• add a new transport
• improve documentation
• fix bugs
• propose new features

Before opening a pull request, please read the contribution guide: CONTRIBUTING.md

It explains:

• pull request title format
• how to work with the monorepo
• when to bump package versions

⭐ Support

If you like this project please star the repository ⭐ It helps the project grow and reach more developers.

Keywords

nestjs messaging library
nestjs message bus
nestjs service bus
nestjs event bus
nestjs distributed systems
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nestjs rabbitmq abstraction
nestjs redis messaging
nestjs nats messaging