Real-time Taxi Platform

Problem Statement

Riders and drivers needed live map synchronization with acceptable latency across heterogeneous mobile networks. Existing HTTP polling was too slow and bandwidth-heavy.

WebSocket Fan-Out with Geo Indexing

I worked on a websocket fan-out with geo indexing where:

• Persistent WebSocket connections per active session
• Redis pub/sub to broadcast location updates to riders
• Batched geohash indexing for fast map tile queries
• Heartbeat + reconnect logic for flaky mobile connections
• Google Maps SDK custom markers and live trajectories

My Contributions

• Implemented WebSocket server with room-based broadcasting
• Built live map UI with React + Google Maps custom overlays
• Optimized payload size via protobuf over websocket frames
• Added client-side reconnect with exponential backoff
• Reduced dropped ride events by 20% with queue replay

Engineering Trade-offs

• Accepted higher server memory footprint for connection state
• Chose room-based routing for predictable scaling before full microservices
• Lowered update frequency during idle to save client battery

Impact