Key Takeaway / TL;DR: WebSockets are the de facto choice for bidirectional, low-latency communication, but they require sticky sessions or a Redis Pub/Sub layer to scale horizontally. Server-Sent Events (SSE) offer a simpler, HTTP-based alternative for one-way server-to-client streaming, with automatic reconnection and better HTTP/2 multiplexing. Redis Pub/Sub acts as a scalable message broker to fan out events across multiple nodes, but you must handle backpressure and connection limi...