WebSockets

WebSockets are a communication protocol that keeps a connection open between a client and a server so both sides can send messages at any time.

They are commonly used for:

• Real-time chat
• Live notifications
• Multiplayer games
• Collaborative editing
• Dashboard updates

WebSockets start with an HTTP upgrade request, then switch to a persistent bidirectional connection.

JavaScript example

In the browser, you create a WebSocket and listen for events:

const socket = new WebSocket("wss://example.com/chat");
 
socket.addEventListener("open", () => {
  socket.send(JSON.stringify({ type: "join", room: "general" }));
});
 
socket.addEventListener("message", (event) => {
  const payload = JSON.parse(event.data);
  console.log("Received:", payload);
});
 
socket.addEventListener("close", () => {
  console.log("Connection closed");
});

This shows the basic pattern:

• open means the connection is ready
• send() transmits a message to the server
• message receives data from the server
• close handles disconnects

Conceptual links

WebSockets are the transport layer underneath systems like Phoenix Framework, where they support real-time message passing. They are often paired with Concurrent Programming and Actor Model style designs.