Rooms and namespaces in NestJS - Mini Project: Build & Apply

Rooms and Namespaces in NestJS WebSocket Gateway

📖 Scenario: You are building a simple chat server using NestJS WebSocket Gateway. The server should support multiple chat rooms and namespaces so users can join specific rooms and namespaces to chat.

🎯 Goal: Create a NestJS WebSocket Gateway that supports two namespaces: /sports and /music. Each namespace should allow clients to join rooms named room1 or room2. When a client sends a message, it should be broadcast only to other clients in the same room and namespace.

📋 What You'll Learn

Create a WebSocket Gateway with two namespaces: '/sports' and '/music'.

Define a method to handle clients joining a room named 'room1' or 'room2'.

Broadcast messages only to clients in the same room and namespace.

Use NestJS decorators and patterns for WebSocket gateways.

💡 Why This Matters

🌍 Real World

Chat applications often need to separate users into different rooms and namespaces to organize conversations by topic or group.

💼 Career

Understanding how to use rooms and namespaces in WebSocket gateways is essential for building scalable real-time applications in NestJS, a popular backend framework.

1

Create the WebSocket Gateway with namespaces

Create a NestJS WebSocket Gateway class called ChatGateway with two namespaces: /sports and /music. Use the @WebSocketGateway decorator with the namespace option for each namespace. Define two classes: SportsGateway and MusicGateway, each decorated with @WebSocketGateway({ namespace: '/sports' }) and @WebSocketGateway({ namespace: '/music' }) respectively.

NestJS

# Create two WebSocket Gateway classes with namespaces '/sports' and '/music'
# Your code here

Need a hint?

Use @WebSocketGateway({ namespace: '/sports' }) to create the sports namespace gateway and similarly for music.

2

Add a method to join rooms

In both SportsGateway and MusicGateway, add a method called handleJoinRoom that takes two parameters: client and room. Use client.join(room) to add the client to the specified room. Use the @SubscribeMessage('joinRoom') decorator on this method.

NestJS

import { WebSocketGateway, SubscribeMessage } from '@nestjs/websockets';

@WebSocketGateway({ namespace: '/sports' })
export class SportsGateway {
  // Add handleJoinRoom method here
  # Your code here
}

@WebSocketGateway({ namespace: '/music' })
export class MusicGateway {
  // Add handleJoinRoom method here
  # Your code here
}

Need a hint?

Use @SubscribeMessage('joinRoom') to listen for join room events and call client.join(room) inside the method.

3

Add message broadcasting within rooms

In both SportsGateway and MusicGateway, add a method called handleMessage decorated with @SubscribeMessage('message'). This method takes client and a payload object with room and text. Use client.to(room).emit('message', text) to broadcast the message to all clients in the same room except the sender.

NestJS

import { WebSocketGateway, SubscribeMessage } from '@nestjs/websockets';

@WebSocketGateway({ namespace: '/sports' })
export class SportsGateway {
  @SubscribeMessage('joinRoom')
  handleJoinRoom(client: any, room: string) {
    client.join(room);
  }

  // Add handleMessage method here
  # Your code here
}

@WebSocketGateway({ namespace: '/music' })
export class MusicGateway {
  @SubscribeMessage('joinRoom')
  handleJoinRoom(client: any, room: string) {
    client.join(room);
  }

  // Add handleMessage method here
  # Your code here
}

Need a hint?

Use client.to(room).emit('message', text) to send messages only to clients in the same room.

4

Export the gateways in a module

Create a NestJS module called ChatModule that imports and exports both SportsGateway and MusicGateway. Use the @Module decorator with providers and exports arrays containing these gateway classes.

NestJS

import { Module } from '@nestjs/common';
// Import gateways here

@Module({
  providers: [
    // Add gateways here
  ],
  exports: [
    // Export gateways here
  ]
})
export class ChatModule {}

Need a hint?

Use @Module decorator with providers and exports arrays to include the gateways.