Message patterns (request-response) in NestJS - Mini Project: Build & Apply

Message Patterns (Request-Response) in NestJS

📖 Scenario: You are building a simple NestJS microservice that responds to messages requesting greetings. This microservice will listen for a specific message pattern and reply with a greeting message.

🎯 Goal: Create a NestJS microservice that listens for a greet message pattern and responds with a greeting message including the name sent in the request.

📋 What You'll Learn

Create a controller with a message pattern handler for greet

Use the @MessagePattern decorator to listen for the greet pattern

Extract the name from the incoming message data

Return a greeting string that includes the name

💡 Why This Matters

🌍 Real World

Microservices often communicate by sending and receiving messages. NestJS provides a simple way to listen for specific message patterns and respond, enabling scalable and decoupled services.

💼 Career

Understanding message patterns and request-response handling in NestJS is essential for backend developers working with microservices and distributed systems.

1

Create the Greeting Controller

Create a class called GreetingController and export it. Inside, define an empty constructor.

NestJS

export class GreetingController {
  // Your code here
}

Need a hint?

Start by defining a class and export it so NestJS can use it as a controller.

2

Add the Message Pattern Decorator

Import @MessagePattern from @nestjs/microservices. Add a method called handleGreet inside GreetingController. Decorate it with @MessagePattern('greet').

NestJS

import { MessagePattern } from '@nestjs/microservices';

export class GreetingController {
  constructor() {}

  // Your code here
}

Need a hint?

Use @MessagePattern('greet') to listen for the 'greet' message pattern.

3

Extract Name and Return Greeting

Inside handleGreet, extract the name property from data. Return a string greeting like `Hello, ${name}!`.

NestJS

import { MessagePattern } from '@nestjs/microservices';

export class GreetingController {
  constructor() {}

  @MessagePattern('greet')
  handleGreet(data: any) {
    // Your code here
  }
}

Need a hint?

Use template strings to create the greeting message.

4

Export the Controller and Prepare for Microservice

Ensure the GreetingController class is exported. This completes the message pattern handler for the microservice.

NestJS

import { MessagePattern } from '@nestjs/microservices';

// Your code here

Need a hint?

Make sure the controller is exported so NestJS can use it.