Real-Time Notification System

Overview

A real-time notification system built using Kafka, Redis, PostgreSQL, and WebSockets. This backend service ensures instant event-driven notifications with efficient storage and retrieval.

Features

• Kafka Producer & Consumer: Events are produced and consumed asynchronously.
• PostgreSQL Storage: Notifications are stored for persistence.
• Redis Caching: Unread notifications are cached for quick access.
• WebSockets: Real-time push notifications to users.
• REST API: Fetch notifications via user ID.

Tech Stack

• Go: Backend service.
• Kafka: Message broker for event-driven processing.
• PostgreSQL: Persistent storage.
• Redis: Fast in-memory cache.
• WebSockets: Real-time communication.

Architecture Flow

1️⃣ Notification Event Ingestion

• The API receives notification data and publishes it to Kafka for reliable message handling.

2️⃣ Event Processing & Storage

• A Kafka Consumer processes the event, storing full notification details in PostgreSQL.
• The notification ID is cached in Redis for quick access to unread notifications.

3️⃣ Fetching Notifications

• When users fetch notifications, the API retrieves IDs from Redis first (low-latency response).
• If needed, full details are fetched from PostgreSQL.

4️⃣ Real-time Notification Delivery

• WebSockets push real-time notifications to actively connected clients.
• If a user views a notification live, it is marked as read immediately in Redis and PostgreSQL.

5️⃣ Manual Read Acknowledgment

• Users can manually mark notifications as read via an API.
• The system removes the notification from Redis and updates PostgreSQL.

Installation

1. Clone the repo:

   git clone https://github.com/likhithkp/realtime-notifications-service.git

2. Set up Kafka, Redis, and PostgreSQL.
3. Configure .env with necessary environment variables.
4. Run the service:

   go run main.go

API Endpoints

• POST /createUser - Create a user first.
• POST /createNotification - Publish a notification.
• GET /notifications/{user_id} - Fetch notifications for a user.
• GET /ws/{user_id} - Listen to live notifications.

License

MIT License.