WebSockets

Definition

A computer communications protocol providing full-duplex communication channels over a single, long-lived TCP connection.

Explain Like I'm New

Standard HTTP is like sending a letter. You ask for the homepage, the server sends it, and the connection is closed. If someone sends you a chat message, the server can't reach you because the connection is dead. WebSockets are a phone call. You call the server, and NEITHER of you hangs up. The line stays open permanently. If someone chats you, the server instantly speaks into the open phone line: 'Hey, new message!'.

Real World Example

Multiplayer browser games, Live stock market tickers, and Chat applications (Discord/Slack). All require instantaneous, two-way communication without the browser constantly refreshing.

Common Use Cases

•Real-time applications
•Collaborative editing (Google Docs)

Interactive Example

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Interview Questions

basic

Are WebSockets unidirectional or bidirectional?

intermediate

Does the client have to constantly 'ask' the server if there is new data in a WebSocket?

Flash Cards

Question

Unidirectional or bidirectional?

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Answer

Bidirectional (Full-duplex). Both the client and the server can send messages to each other at the exact same time.

Question

Does the client have to ask?

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Answer

No. Unlike HTTP 'Long Polling', the client just sits quietly. The server PUSHES the data down the open connection the millisecond it becomes available.