Database

Chat room architecture covering message routing, history, moderation, and scalable room-based real-time systems

Real-time collaborative editing with CRDTs and Operational Transform for conflict-free concurrent document editing

User presence system design for tracking online/offline status, typing indicators, and activity in real-time apps

Reconnection and offline resilience patterns for WebSocket apps including retry strategies and state synchronization

Scaling WebSocket applications with Redis pub/sub, sticky sessions, horizontal scaling, and load balancing strategies

Server-Sent Events (SSE) patterns for efficient unidirectional real-time streaming from server to client

Socket.IO patterns for event-driven real-time communication with automatic reconnection and room management

WebSocket API fundamentals including connection lifecycle, message framing, and browser/server implementations