WebSocket

A protocol enabling full-duplex, real-time communication between client and server.

WebSocket is a communication protocol that provides full-duplex, bidirectional communication channels over a single TCP connection. Unlike HTTP, WebSocket allows both client and server to send messages at any time.

WebSocket vs HTTP

Feature	WebSocket	HTTP
Connection	Persistent	Request-Response
Direction	Bidirectional	Client-initiated
Overhead	Low (after handshake)	Headers on every request
Real-time	Yes	Polling required

Use Cases

Chat Applications: Real-time messaging
Live Dashboards: Stock prices, analytics
Gaming: Multiplayer game state
Notifications: Push updates to clients
Collaborative Tools: Google Docs-style editing

Connection Lifecycle

Handshake: HTTP upgrade request
Open: Connection established
Message: Data exchange
Close: Connection terminated

Best Practices

Implement reconnection logic
Use heartbeat/ping-pong for connection health
Handle connection errors gracefully
Consider fallback to polling

Code Examples

Browser WebSocket

const ws = new WebSocket("wss://api.example.com/socket");

ws.onopen = () => {
  console.log("Connected");
  ws.send(JSON.stringify({ type: "subscribe", channel: "updates" }));
};

ws.onmessage = (event) => {
  const data = JSON.parse(event.data);
  console.log("Received:", data);
};

ws.onclose = () => console.log("Disconnected");

Related Terms

Server-Sent Events (SSE)

A standard for pushing real-time updates from server to client over HTTP.

Mock Server

A fake server that simulates API responses for testing and development purposes.

API Testing

The process of verifying that APIs work correctly, securely, and perform well.

OpenAPI Specification

A standard format for describing REST APIs, enabling documentation and code generation.