5. Distributed Systems
WebSockets & Real-Time Features
Build real-time features with authentication, reconnects, fan-out and horizontal scaling in mind.
Lesson overview
WebSockets introduce long-lived connections, reconnects, authorization and fan-out. Authenticate subscriptions and use a broker or managed service when multiple instances must exchange events.
Learning path
Theory → Example → Code → Practice → Quiz → Challenge → Completion
Step 1
Theory
WebSockets introduce long-lived connections, reconnects, authorization and fan-out. Authenticate subscriptions and use a broker or managed service when multiple instances must exchange events.
Step 2
Example
A chat client can reconnect, re-fetch missed messages over HTTP, authorize room subscriptions, then resume real-time delivery.
Step 3
Code
typescript
socket.on("subscribe", async ({ roomId }) => {
await authorizeRoom(user.id, roomId);
socket.join(room:${roomId});
});
Step 4
Practice
Review your current application and apply WebSockets & Real-Time Features. Document the current behavior, one production risk, the change you would make, and how you would verify it.
Step 5
Quiz
1. What is the central production concern in "WebSockets & Real-Time Features"?
Step 6
Challenge
Design a production-ready implementation for WebSockets & Real-Time Features. Include failure handling, security considerations, observability, testing and a rollback or recovery path where applicable.
Complete every stage
Work through every step in order, then the lesson will be marked complete.
Each chapter and subtopic has its own public URL under /full-stack-to-production.