The Notification Service is a production-ready, scalable backend microservice built using Node.js, Express, Kafka, and MongoDB, aimed at handling asynchronous notification workflows in modern distributed systems. This service provides a RESTful API interface to allow applications or microservices to trigger and retrieve notifications in a decoupled manner using Apache Kafka as the event streaming backbone. It follows a publisher-subscriber architecture, which enables scalable and fault-tolerant communication between services, ideal for real-time systems, task updates, alerts, or logs. This project uses Swagger UI to provide interactive API documentation.
🧰 Technologies Used
| Tech | Purpose |
|---|---|
| Node.js | Runtime for server-side logic |
| Express.js | Web framework to handle REST APIs |
| MongoDB | NoSQL database to store notifications |
| Swagger (OpenAPI) | API documentation and testing UI |
| Docker & Docker Compose | Containerized development and orchestration |
| KafkaJS | Kafka client for Node.js |
| dotenv | Environment variable management |
🔧 System Architecture:
📁 Folder Structure
⚙️ Installation & Setup:
Ensure you have the following installed: -Node.js (v16 or later) -npm (Node package manager) -Kafka (Local instance or via Docker) -MongoDB (Local instance or via Mongo Atlas) -Docker & Docker Compose (optional but recommended for easier setup
📦 Clone the Repository -git clone https://github.com/YashSnew/notification-service.git -cd notification-service
📥 Install Dependencies
npm install
🧪 Run MongoDB and Kafka (Docker - Recommended) If you don’t have Kafka or MongoDB installed locally, use Docker:
docker-compose up -d
To Check if Kafka is running
docker ps
🚀 Start the Notification Service
npm start
Expected output: MongoDB Connected ✅ Kafka Producer connected 🚀 Server running on port 3000
🔁 API Endpoints
➕ To Create Notification: POST /notification
Request Body: { "userId": "1234567890", "type": "info", "message": "Your task is completed." }
➡️To Get All Notifications: GET /notification
📚 API Documentation (Swagger UI):
http://localhost:3000/api-docs
🧠 Assumptions: ✅ Kafka and Zookeeper are running either locally or via Docker as defined in docker-compose.yml. ✅ MongoDB is accessible and properly configured in the .env file or running on localhost:27017. ✅ Kafka topics are pre-created, or Kafka auto-topic creation is enabled (typically enabled by default). ✅ The application runs in a Node.js (v14+) environment with npm installed. ✅ This service assumes basic familiarity with Kafka, Express.js, and REST APIs. ✅ Kafka broker address and MongoDB URI are correctly set in your environment variables. ✅ No authentication or rate limiting has been implemented — this is a foundational service that can be extended as needed.