Microservices and MVC in a NestJS Project

Microservices and MVC in a NestJS Project NestJS is a progressive Node.js framework that provides a solid structure for building scalable applications. It supports both Microservice architecture and MVC (Model-View-Controller) pattern, allowing developers to choose the best fit for their use case. 1. Microservices in NestJS What are Microservices? Microservices architecture allows an application to be broken down into multiple independent services, each handling a specific responsibility. These services communicate using lightweight mechanisms such as HTTP, WebSockets, or messaging brokers (Kafka, RabbitMQ, etc.). How to Implement Microservices in NestJS? NestJS provides built-in support for microservices via the @nestjs/microservices module. Step 1: Install Required Dependencies npm install @nestjs/microservices Step 2: Create a Microservice Define a microservice that listens on a specific transport (e.g., TCP). import { NestFactory } from '@nestjs/core'; import { MicroserviceOptions, Transport } from '@nestjs/microservices'; import { AppModule } from './app.module'; async function bootstrap() { const app = await NestFactory.createMicroservice(AppModule, { transport: Transport.TCP, // Using TCP transport options: { host: '127.0.0.1', port: 3001 }, }); await app.listen(); console.log('Microservice is running on port 3001'); } bootstrap(); Step 3: Create a Microservice Handler Inside a service, define message patterns. import { Controller } from '@nestjs/common'; import { MessagePattern } from '@nestjs/microservices'; @Controller() export class MathController { @MessagePattern({ cmd: 'sum' }) // Message-based communication sum(data: number[]): number { return data.reduce((a, b) => a + b, 0); } } Step 4: Create a Client (API Gateway or Another Microservice) The client will send messages to the microservice. import { Controller, Get } from '@nestjs/common'; import { Client, ClientProxy, Transport } from '@nestjs/microservices'; @Controller() export class AppController { @Client({ transport: Transport.TCP, options: { host: '127.0.0.1', port: 3001 } }) private client: ClientProxy; @Get('sum') async getSum(): Promise { return this.client.send({ cmd: 'sum' }, [3, 5]).toPromise(); } } Benefits of Microservices in NestJS ✅ Scalability – Each service scales independently. ✅ Decoupling – Services can be deployed separately. ✅ Flexibility – Services can be written in different programming languages. 2. MVC in NestJS What is MVC? MVC (Model-View-Controller) is a design pattern that separates application logic into three layers: Model (M): Handles data and business logic. View (V): Responsible for UI rendering. (NestJS usually does not use this since it's more backend-focused.) Controller (C): Handles requests and responses. How to Implement MVC in NestJS? Step 1: Create a Controller Controllers handle HTTP requests and return responses. import { Controller, Get } from '@nestjs/common'; @Controller('users') export class UsersController { @Get() getUsers(): string { return 'List of users'; } } Step 2: Create a Service The service contains business logic and interacts with the database. import { Injectable } from '@nestjs/common'; @Injectable() export class UsersService { getAllUsers(): string[] { return ['Alice', 'Bob', 'Charlie']; } } Step 3: Use the Service in the Controller Inject the service into the controller to fetch data. import { Controller, Get } from '@nestjs/common'; import { UsersService } from './users.service'; @Controller('users') export class UsersController { constructor(private readonly usersService: UsersService) {} @Get() getUsers(): string[] { return this.usersService.getAllUsers(); } } Step 4: Register Components in a Module A module groups related components together. import { Module } from '@nestjs/common'; import { UsersController } from './users.controller'; import { UsersService } from './users.service'; @Module({ controllers: [UsersController], providers: [UsersService], }) export class UsersModule {} Comparison: Microservices vs. MVC in NestJS Feature Microservices MVC Architecture Distributed (multiple services) Monolithic (single codebase) Scalability High (each service scales independently) Limited (entire app scales together) Communication Message-based (Kafka, RabbitMQ, etc.) Direct function calls (synchronous) Deployment Services deployed separately Deployed as a single unit Best For Large, scalable applications Small to medium-sized applications Conclusion Use Microservices if you need scalability, independent deployments, or different services for different teams. Use MVC if you're

Feb 12, 2025 - 13:13

Microservices and MVC in a NestJS Project

NestJS is a progressive Node.js framework that provides a solid structure for building scalable applications. It supports both Microservice architecture and MVC (Model-View-Controller) pattern, allowing developers to choose the best fit for their use case.

1. Microservices in NestJS

What are Microservices?

Microservices architecture allows an application to be broken down into multiple independent services, each handling a specific responsibility. These services communicate using lightweight mechanisms such as HTTP, WebSockets, or messaging brokers (Kafka, RabbitMQ, etc.).

How to Implement Microservices in NestJS?

NestJS provides built-in support for microservices via the @nestjs/microservices module.

Step 1: Install Required Dependencies

npm install @nestjs/microservices

Step 2: Create a Microservice

Define a microservice that listens on a specific transport (e.g., TCP).

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.TCP,  // Using TCP transport
    options: { host: '127.0.0.1', port: 3001 },
  });

  await app.listen();
  console.log('Microservice is running on port 3001');
}

bootstrap();

Step 3: Create a Microservice Handler

Inside a service, define message patterns.

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

@Controller()
export class MathController {
  @MessagePattern({ cmd: 'sum' })  // Message-based communication
  sum(data: number[]): number {
    return data.reduce((a, b) => a + b, 0);
  }
}

Step 4: Create a Client (API Gateway or Another Microservice)

The client will send messages to the microservice.

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

@Controller()
export class AppController {
  @Client({ transport: Transport.TCP, options: { host: '127.0.0.1', port: 3001 } })
  private client: ClientProxy;

  @Get('sum')
  async getSum(): Promise<number> {
    return this.client.send({ cmd: 'sum' }, [3, 5]).toPromise();
  }
}

Benefits of Microservices in NestJS

✅ Scalability – Each service scales independently.

✅ Decoupling – Services can be deployed separately.

✅ Flexibility – Services can be written in different programming languages.

2. MVC in NestJS

What is MVC?

MVC (Model-View-Controller) is a design pattern that separates application logic into three layers:

Model (M): Handles data and business logic.
View (V): Responsible for UI rendering. (NestJS usually does not use this since it's more backend-focused.)
Controller (C): Handles requests and responses.

How to Implement MVC in NestJS?

Step 1: Create a Controller

Controllers handle HTTP requests and return responses.

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

@Controller('users')
export class UsersController {
  @Get()
  getUsers(): string {
    return 'List of users';
  }
}

Step 2: Create a Service

The service contains business logic and interacts with the database.

import { Injectable } from '@nestjs/common';

@Injectable()
export class UsersService {
  getAllUsers(): string[] {
    return ['Alice', 'Bob', 'Charlie'];
  }
}

Step 3: Use the Service in the Controller

Inject the service into the controller to fetch data.

import { Controller, Get } from '@nestjs/common';
import { UsersService } from './users.service';

@Controller('users')
export class UsersController {
  constructor(private readonly usersService: UsersService) {}

  @Get()
  getUsers(): string[] {
    return this.usersService.getAllUsers();
  }
}

Step 4: Register Components in a Module

A module groups related components together.

import { Module } from '@nestjs/common';
import { UsersController } from './users.controller';
import { UsersService } from './users.service';

@Module({
  controllers: [UsersController],
  providers: [UsersService],
})
export class UsersModule {}

Comparison: Microservices vs. MVC in NestJS

Feature	Microservices	MVC
Architecture	Distributed (multiple services)	Monolithic (single codebase)
Scalability	High (each service scales independently)	Limited (entire app scales together)
Communication	Message-based (Kafka, RabbitMQ, etc.)	Direct function calls (synchronous)
Deployment	Services deployed separately	Deployed as a single unit
Best For	Large, scalable applications	Small to medium-sized applications

Conclusion

Use Microservices if you need scalability, independent deployments, or different services for different teams.
Use MVC if you're building a small to medium monolithic application with a structured architecture.

NestJS provides built-in support for both architectures, allowing developers to choose the right approach for their needs.