Understanding WebSockets Under The Hood

WebSocket Under the Hood#

WebSocket is a communication protocol that facilitates full-duplex communication channels over a single, long-lived connection. It's designed to be efficient and minimize overhead compared to traditional HTTP-based communication. Here's a simplified explanation of how WebSocket works under the hood:

1. Handshake:#

The process begins with a WebSocket handshake initiated by the client. The client sends a standard HTTP request to the server, expressing the desire to upgrade the connection to a WebSocket connection. The client includes a special header, Upgrade: webSocket, indicating the intention to establish a WebSocket connection. If the server supports WebSocket and agrees to the upgrade, it responds with an HTTP 101 status code (Switching Protocols), confirming a successful upgrade.

2. Persistent Connection:#

Once the handshake is complete, the connection is upgraded from HTTP to WebSocket. This results in a persistent, full-duplex connection, eliminating the need to repeatedly open and close connections for each message.

3. Frame-Based Communication:#

WebSocket communication is frame-based, where data is exchanged in small binary or text frames between the client and the server. Each frame can carry a part of the message, and multiple frames can be used to transmit a larger message.