Real-Time Collaboration Platform
Built a scalable WebSocket-based collaboration service handling 10K+ concurrent users with sub-50ms latency.
The Problem
Existing collaboration tools suffered from high latency and poor scalability when handling large numbers of concurrent users. Teams experienced delays in message delivery, connection drops during peak usage, and inconsistent user experiences across different geographical regions.
Constraints & Requirements
Performance: Sub-50ms latency for message delivery under load
Scalability: Handle 10K+ concurrent users without degradation
Reliability: Maintain 99.9% uptime with automatic recovery from failures
Consistency: Ensure message ordering and delivery guarantees
Security: Protect against unauthorized access and data interception
Architecture & Approach
System Design
Designed a horizontally scalable WebSocket server using Node.js with Redis as the message broker and state store. Implemented connection pooling, load balancing, and automatic failover mechanisms.
Key Technical Decisions
WebSocket over HTTP polling: Chose persistent connections for real-time updates instead of inefficient polling
Redis Pub/Sub: Used Redis for lightweight, fast message broadcasting between server instances
Sticky Sessions: Implemented session affinity to maintain connection state
Horizontal Scaling: Designed stateless server nodes that can be added/removed dynamically
Technologies Used
Results & Impact
Scale: Successfully handled 10K+ concurrent users in testing
Performance: Achieved sub-30ms average latency under load
Reliability: 99.95% uptime over 30-day testing period
Efficiency: 70% reduction in server resource usage compared to previous polling-based solution
Key Learnings
Connection Management: Proper WebSocket connection lifecycle management is critical for preventing memory leaks
Message Ordering: In distributed systems, guaranteeing message ordering requires careful sequencing and buffering strategies
Horizontal Scaling: Stateless services dramatically simplify scaling and deployment complexity
Monitoring: Real-time metrics and logging are essential for diagnosing production issues in real-time systems