Microservices in TypeScript: Where to Start in 2024

Microservices in TypeScript: Your First Step Towards Modular Architecture

Imagine you are building a house. You could erect one huge wall and then add rooms to it. But if one room breaks, the entire building suffers. The alternative is to build separate modules: a kitchen, a bedroom, a living room, each with its own wiring and plumbing. This is roughly how microservices work — independent, loosely coupled components that communicate over a network.

TypeScript for microservices is not just a trendy fad, but a tool that saves you from chaos. Static typing catches errors at compile time, not in production. In this article, we'll break down where to start if you want to move from a monolith to microservices in TypeScript. No fluff, with real code examples.

Why TypeScript, Not Plain JavaScript?

When you write microservices, each service is a separate project. Without types, it's easy to get confused: what data format does service A expect, what does service B return? TypeScript solves this problem:

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• Interfaces and Types — you clearly define contracts between services.
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• Autocomplete and Refactoring — the IDE suggests object fields, and renaming doesn't break code.
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• Compatibility with Node.js — TypeScript compiles to JavaScript, works wherever Node is present.
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Example: imagine the order service sends data to the delivery service. Without types, you could accidentally pass a string instead of a number. TypeScript will say: "Hey, a number is expected here, but you're sending a string."

Toolkit for Getting Started

To get started, you'll need:

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• Node.js (version 18+) — the runtime environment.
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• TypeScript — install globally or in the project.
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• NestJS — a framework for server applications. It natively supports microservice architecture.
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• RabbitMQ or NATS — message brokers for asynchronous communication.
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• Docker — containerization for each service.
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Don't worry, all of this can be set up in 15 minutes.

Step 1: Create Your First Microservice with NestJS

NestJS is like Angular for the backend. It uses decorators, modules, and providers. Let's install it:

npm i -g @nestjs/cli\nnest new user-service\ncd user-service\nnpm install @nestjs/microservices

Now let's turn a regular application into a microservice. Open main.ts:

import { NestFactory } from '@nestjs/core';\nimport { MicroserviceOptions, Transport } from '@nestjs/microservices';\nimport { AppModule } from './app.module';\n\nasync function bootstrap() {\n  const app = await NestFactory.createMicroservice<MicroserviceOptions>(\n    AppModule,\n    {\n      transport: Transport.TCP, // or Redis, RabbitMQ\n      options: {\n        host: '0.0.0.0',\n        port: 3001,\n      },\n    },\n  );\n  await app.listen();\n  console.log('User microservice is listening on port 3001');\n}\nbootstrap();

We've created a microservice that listens on TCP port 3001. Now let's add a message handler in app.controller.ts:

import { Controller } from '@nestjs/common';\nimport { MessagePattern, Payload } from '@nestjs/microservices';\n\n@Controller()\nexport class AppController {\n  @MessagePattern('get_user')\n  getUser(@Payload() data: { id: number }) {\n    // Simulating a database query\n    return { id: data.id, name: 'Alice', email: 'alice@example.com' };\n  }\n}

That's it! The first microservice is ready. It accepts a message with the pattern get_user and returns user data.

Step 2: Create a Second Service and Organize Communication

Let's make another service — order-service. It will request data from user-service.