UniBus

UniBus is a scalable, real-time transportation network platform designed for SRM University. It provides a native mobile experience for students to track college buses and for drivers to broadcast live location data with minimal latency.

System Status: Architecture upgraded to handle 10,000+ concurrent users via Redis geospatial caching and WebSocket clustering.

---

🏗 High-Scale Architecture

This project has moved beyond a simple web app to a Distributed Real-Time System designed like Uber/Rapido.

The "Stack Shift" (MRVN Stack)

We utilize the MRVN (MongoDB, Redis, Varnish/View [React Native], Node.js) architecture to ensure sub-200ms latency.

Component	Technology	Purpose
Mobile Apps	React Native	Cross-platform (iOS/Android) native performance. Required for background GPS services and Mapbox vector rendering.
Backend API	Node.js (Express/NestJS)	High-throughput event loop for handling thousands of concurrent WebSocket connections.
Live Data Store	Redis (Geospatial)	In-memory caching for live bus coordinates. This avoids database I/O bottlenecks.
Persistent DB	MongoDB	Long-term storage for user profiles (Students/Drivers), Route definitions, and Shift logs.
Maps	Mapbox GL	Vector-based maps allowing custom "Night Mode" styles (Uber-like) and high-performance markers.
Real-Time Engine	Socket.io + Redis Adapter	Enables horizontal scaling. A driver on Server A can talk to a student on Server B.

---

📐 System Design & Data Flow

1. Driver App (Emitter):
   • Runs a foreground service (notification) to keep GPS alive even when the phone is locked.
   • Emits BUS_LOCATION_UPDATE events via WebSocket every 3 seconds.
2. API Gateway (Load Balancer):
   • Nginx distributes incoming WebSocket connections across multiple Node.js instances.
3. Backend Cluster:
   • Receives coordinates and performs a GEOADD command to Redis.
   • Publishes the update to a specific Redis channel (e.g., route_01).
4. Student App (Listener):
   • Subscribes to the specific route channel.
   • Receives updates immediately via the Redis Pub/Sub mechanism.

---

📂 Project Structure (Monorepo)

/unibus-root
├── backend/                  # Node.js Scalable Server
│   ├── src/
│   │   ├── config/           # Redis & Mongo connections
│   │   ├── controllers/      # Auth & API Logic
│   │   ├── gateways/         # WebSocket Gateways (Socket.io)
│   │   ├── models/           # Mongoose Schemas (User, Route)
│   │   └── services/         # RedisService (Geo-hashing logic)
│   ├── redis.conf            # Redis configuration tuning
│   └── ecosystem.config.js   # PM2 Cluster mode config
│
├── mobile-driver/            # React Native App for Drivers
│   ├── src/
│   │   ├── services/         # Background Geolocation Service
│   │   ├── screens/          # Login, RouteSelection, BroadcastView
│   │   └── socket/           # Emitter logic
│   └── android/              # Native Android manifests (Permissions)
│
├── mobile-student/           # React Native App for Students
│   ├── src/
│   │   ├── components/       # Custom Map Markers, BusCard
│   │   ├── screens/          # Dashboard, MapView, RouteList
│   │   └── hooks/            # useBusLocation (Socket hook)
│   └── ios/                  # Native iOS Info.plist (Permissions)
│
└── docs/                     # System Diagrams & API Docs