🛒 Personalized Notification System — Microservices-Based E-commerce Backend

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🧠 Overview

A Production-Ready Microservices-Based Personalized Notification System for an E-commerce Platform, built with:

• 🔁 Event-driven architecture (RabbitMQ)
• ⚡ Unified GraphQL Gateway
• 🔐 JWT-based Auth & Role Management
• 📦 Independent MongoDB-backed microservices
• 📊 Monitoring with Prometheus, Grafana, and Loki
• 🐳 Fully Dockerized — run locally in seconds

🚀 Designed for high scalability, real-time communication, and developer productivity.

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🔧 Architecture

graph TD
  Client["🧑‍💻 Client (Postman / GraphQL Playground)"]
  Gateway["🚪 GraphQL Gateway"]
  Users["👤 User Service"]
  Notifications["🔔 Notification Service"]
  Products["📦 Product Service"]
  Orders["🧾 Order Service"]
  Scheduler["⏰ Scheduler Service"]
  RabbitMQ["📨 RabbitMQ (Broker)"]
  Redis["⚡ Redis (Cache)"]
  Loki["📄 Loki (Logs)"]
  Prometheus["📈 Prometheus"]
  Grafana["📊 Grafana Dashboard"]

  Client --> Gateway
  Gateway --> Users
  Gateway --> Notifications
  Gateway --> Products
  Gateway --> Orders

  Users -->|MongoDB| DB1[(Users DB)]
  Notifications -->|MongoDB| DB2[(Notifications DB)]
  Products -->|MongoDB| DB3[(Products DB)]
  Orders -->|MongoDB| DB4[(Orders DB)]

  Orders -- OrderEvents --> RabbitMQ
  Products -- InventoryUpdate --> RabbitMQ
  Notifications -- ListenEvents --> RabbitMQ
  Scheduler -- Promotions & Triggers --> RabbitMQ

  Gateway --> Redis
  Loki --> Grafana
  Prometheus --> Grafana

Loading

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🧩 Services

🧑‍💼 User Service

• Register/Login with JWT
• User preferences for notification types
• Preference updates & authentication middleware

🔔 Notification Service

• Store, mark, fetch notifications
• Event listeners for orders, promos, recos
• Respect user preferences

📦 Product Service

• Product catalog management
• Inventory updates via order events

🧾 Order Service

• Order placement, updates, and tracking
• Emits events for inventory + user notifications

⏰ Scheduler Service

• Cron-based notification triggers
• Periodic promotions & order status checks

🚪 GraphQL Gateway

• Unified API layer
• Authentication middleware
• Aggregates data from all microservices
• Redis-based caching

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📬 Event-Driven Communication

All services communicate via RabbitMQ. Each service emits and consumes events based on its responsibilities:

Event	Emitter	Consumers
order.placed	Orders	Products, Notifications
product.out_of_stock	Products	Notifications
promo.campaign	Scheduler	Notifications
recommendation.generated	Scheduler	Notifications

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🔐 Authentication

• JWT Tokens (generated in User Service)
• All protected GraphQL mutations require a valid token
• Token is verified in the GraphQL Gateway

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📊 Observability & Monitoring

• Loki → stores logs from all services
• Prometheus → scrapes /metrics from services
• Grafana → visualizes both (use dashboards or build your own)

📸 Screenshots:

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⚙️ Local Development Setup

📦 Prerequisites

• Node.js v16+
• Docker & Docker Compose

🧪 Running Locally

git clone https://github.com/narasimha-1511/ecommerce-microservices.git
cd ecommerce-microservices

# Start the entire ecosystem (DBs, Gateway, Microservices, Monitoring tools)
docker compose up --build

• Gateway accessible at: http://localhost:8000/graphql
• Grafana: http://localhost:3000 (default user/pass: admin / admin)
• Prometheus: http://localhost:9090
• Loki: http://localhost:3100
• RabbitMQ Dashboard: http://localhost:15672 (default user/pass: guest / guest)

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📮 Postman Collection

You can test all APIs using the Postman collection below:

https://www.postman.com/aviation-geologist-50887892/workspace/narasimha-projects/collection/68603dd24acaedd6ec650f04?action=share&creator=42408643&active-environment=42408643-d918b243-596b-460f-9146-8fbb744bc02e

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📁 Folder Structure

ecommerce-microservices/
│
├── gateway/               → GraphQL API Gateway
├── services/
│   ├── users/             → User Service
│   ├── notifications/     → Notification Service
│   ├── products/          → Product Service
│   ├── orders/            → Order Service
│   └── scheduler/         → Scheduler Service
│
├── monitoring/            → Prometheus config
├── docker-compose.yml     → All-in-one orchestration
└── README.md

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