TCP transport in NestJS - Mini Project: Build & Apply

Basic TCP Transport with NestJS

📖 Scenario: You are building a simple NestJS microservice that communicates over TCP. This microservice will receive a message and respond with a greeting.

🎯 Goal: Create a NestJS microservice using TCP transport that listens for a message with the pattern { cmd: 'greet' } and responds with a greeting message.

📋 What You'll Learn

Create a NestJS microservice using TCP transport

Define a message pattern { cmd: 'greet' }

Implement a handler that returns a greeting string

Start the microservice to listen for TCP messages

💡 Why This Matters

🌍 Real World

TCP transport is used in microservices to enable fast and efficient communication between services in distributed systems.

💼 Career

Understanding TCP transport in NestJS is valuable for backend developers working with microservices architecture and building scalable server applications.

1

Create the microservice bootstrap function

Create a function called bootstrap that creates a NestJS microservice using TcpTransport from @nestjs/microservices. Use await to create the microservice instance and assign it to a variable called app.

NestJS

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

async function bootstrap() {
  // Your code here
}

Need a hint?

Use NestFactory.createMicroservice with AppModule and set transport to TcpTransport.

2

Add microservice listen configuration

Inside the bootstrap function, add a line to start the microservice listening by calling await app.listen().

NestJS

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

async function bootstrap() {
  const app = await NestFactory.createMicroservice(AppModule, {
    transport: TcpTransport,
  });
  // Start listening
  // Your code here
}

Need a hint?

Call await app.listen() to start the microservice.

3

Create a message handler for the 'greet' command

In AppController, create a method called handleGreet decorated with @MessagePattern({ cmd: 'greet' }). This method should return the string 'Hello from TCP microservice!'.

NestJS

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

@Controller()
export class AppController {
  // Add a message handler for { cmd: 'greet' }
  // Your code here
}

Need a hint?

Use @MessagePattern decorator with the pattern { cmd: 'greet' } on the method.

4

Add AppController to AppModule providers

In AppModule, add AppController to the controllers array to register it.

NestJS

import { Module } from '@nestjs/common';
import { AppController } from './app.controller';

@Module({
  // Add AppController to controllers
  // Your code here
})
export class AppModule {}

Need a hint?

Include AppController in the controllers array of @Module.