Full-duplex realtime

• Client ↔ Server
  • Both time communicate anytime
• One persistent connection
• Not request-response anymore

Normal HTTP

Browser                    Server

   ───── GET /products ──────>
   <──── JSON response ───────
   
then connection done

Web Socket Workflow:

1. HTTP handshake
2. Upgrade to WebSocket
3. Persistent connection
4. Messages flow both ways

Browser                    Server

   ─────── CONNECT ──────────>
   <────── CONNECTED ─────────

   ← connection stays open →
   
   
WebSocket Server

Connection 1
 ├── socket
 ├── user/client information
 └── connection state

Connection 2
 ├── socket
 ├── user/client information
 └── connection state

Connection 3
 ├── socket
 ├── user/client information
 └── connection state

...
Connection 100

• Not mean the server is running a CPU loop for every user.
• “I have these sockets open. Wake me when something happens.”
• Use async/event-driven I/O, so one server process can manage many connections.