# Web Socket

2 min read, 368 words web socket ws api

How to write Web Socket API client (included with browsers) and server?

IETF RFC-6455
Low overhead <1% HTTP, low latency
open TCP under HTTP, SSL/TLS security
Full Duplex Communication RT communication protocol over single TCP Connection
Used for delivery of dynamic data, doesnt replace HTTP
HTTP Upgrade request, do you spek web-socket? then Handshake
Web socket protocol supports text and binary data. In terms of Javascript, text refers to as a string, while binary data is represented like ArrayBuffer.

Just messaging to servers from IoT

Why use web sockets

Workarounds to web socket

# web socket server

express app using ws package
What to do when client connects?
What to send?
What to do when recieves a message from client?

# web socket client API

Connection events open, message, close, send

WebSockets as REST APIs

useEffect(() => {
  wsc.current = new WebSocket("ws://localhost:8080");
  wsc.current.onopen = (msg) =>
    console.log("wsc opened " + JSON.stringify(msg));
  wsc.current.onclose = (msg) =>
    console.log("wsc closed " + JSON.stringify(msg));
  wsc.current.message = (msg) => console.log("recieved " + JSON.stringify(msg));

  return () => {
    wsc.current.close();
  };
}, []);

# Use clases

Simulate Real Time, Polling and Long Polling

Brodcast messages to all clients, group chat
IoT type use cases
exxchange, trading applications
Replay things, transactions
Chat apps XMPP (opens new window)
Multiplayer Games, Collaborative Apps, Developer Tools, Location dependent apps
Currency Exchanges

# Issues

They're unreliable & hard to scale
the connection might drop, and you might find yourself doing polling for the sake of reliability...

# questions

How well does WS scale? #people making || connections? HTTP is probably behind LB
How reselient is it to connection drops?
Does regular browser security constraints apply? like CORS?
Can data be compressed (gzip) through WS?
Can send bytes? plain text? yes => watch it in Wireshark
How to uniquely identify each client?
High volume storage backends for WS? (opens new window)
Express vs Django? (opens new window)
web socket client using react hooks (opens new window)

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