📦 Microservices Architecture with NestJS, Go, and NATS

📖 Overview

This project implements a microservices architecture with a central HTTP gateway and NATS-based internal service communication.

• NestJS is used as an API Gateway / BFF, exposing HTTP endpoints and translating requests into internal commands.
• Go services handle core business domains such as authentication and customers, each owning its own data and logic.
• NATS is used as an internal messaging transport, primarily for synchronous request–reply (RPC) communication between services.

The system is designed with clear service boundaries, independent deployments, and the flexibility to evolve toward asynchronous, event-driven patterns in the future.

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🧠 Architecture Summary

• External communication: HTTP
• Internal communication: NATS (request–reply / RPC)
• Service ownership: Each service owns its own data and business logic
• Authentication: Handled at the gateway level using JWT

⚠️ Note
This project currently uses RPC-style communication over NATS, not a full event-driven architecture.

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🛠️ Tech Stack

• NestJS — API Gateway & Products service
• Golang — Authentication & Customers services
• NATS Server — Internal RPC transport (command bus)
• PostgreSQL (Northwind) — Relational data storage
• MongoDB — Authentication-related data
• JWT — Authentication & authorization

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🧩 Services Overview

Service	Language	Responsibility
Gateway	NestJS	HTTP entry point, JWT validation, request routing, and translation to NATS RPC
Authentication	Go	User authentication and identity management
Customers	Go	Customer data and operations
Products	NestJS	Product management and operations

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🔄 Communication Model

External (Client → System)

• Clients communicate with the system via HTTP
• The gateway handles:
  • Authentication (JWT)
  • Routing
  • Request validation

Internal (Service → Service)

• Services communicate via NATS request–reply (RPC)
• Each request:
  • Is handled by exactly one service
  • Returns a response or error
• No direct HTTP calls between services

This approach keeps services decoupled from transport details while maintaining synchronous control flow where needed.

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🚀 Getting Started

Prerequisites

Ensure you have the following installed:

• Node.js
• Go
• NATS Server
• PostgreSQL
• MongoDB

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Installation

1. Clone the repository
2. Configure environment variables for each service and the gateway using .env files
3. Start required infrastructure (databases, NATS)
4. Run services individually

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📌 Notes on Architecture

• No shared databases between services
• NATS is used as a command bus, not as a public gateway
• Services are independently deployable and scalable