WebSocket Explained: How It Works and What to Look For
WebSocket creates a persistent, two-way message channel between a client and a server.
Published by Protocol Explorer · Reviewed
How WebSocket works
An HTTP/1.1 upgrade request starts the connection; a successful 101 response switches the protocol. Each endpoint can then send frames independently.
What to look for in an exchange
Inspect the Upgrade and Sec-WebSocket headers, then the frame opcode, length and masking. Client-to-server frames are masked; masking is not encryption.
Follow an example step by step
- Find the HTTP upgrade request and its Upgrade and Connection headers.
- Check for a successful 101 Switching Protocols response before interpreting subsequent bytes as WebSocket frames.
- Inspect frame opcode, payload length and the client masking key when present.
Common interpretation mistake
A 101 response alone does not mean every later application message was delivered or processed.
Key point to remember
WebSocket frames can carry text, binary, ping, pong and close messages; encryption requires a secure transport such as WSS.
Explore the protocol
The WebSocket overview is free without an account. Its full interactive lesson is included in Protocol Explorer Pro, a one-time $4.99 purchase; an account is required to buy Pro and restore the licence across devices.
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Specification
Read the primary specification for WebSocket for the authoritative protocol details. The interactive scenario is a simplified teaching model, not a capture of your network.
Continue learning
How to read a packet · TCP · UDP · HTTPS