WebSocket Live Device Channel
Maintain a bidirectional channel for low-latency dashboards and commands.
Topology and objective
Device ↔ WebSocket server ↔ local dashboard.
Hardware and tools
- Supported development board
- USB data cable
- Current-limited supply
- Serial monitor and logic analyser when applicable
Security and RF safety
- Prefer WSS outside isolated labs.nAuthenticate during connection without leaking tokens in logs.nValidate message type, length and command allowlist.
Practical procedure
- Open a secure WebSocket connection.nSend a hello/device-identification frame.nStream bounded telemetry messages.nReceive a command and return acknowledgement.nTest ping/pong and reconnect backoff.
Telemetry / payload
{"type":"telemetry","seq":42,"value":27.1}Starter code / config
wss://lab.example.test/devicen{"type":"command","id":"cmd-7","action":"sample_now"}Expected results
| Checkpoint | Expected | Tool |
|---|---|---|
| Bidirectional | Command and acknowledgement share ID | Browser consolenReconnect |
Troubleshooting
| Symptom | Check | Action |
|---|---|---|
| Connection closes | Inspect close code and heartbeat | Fix auth/timeout then reconnectnCommands repeat |
Local-only sandbox
Commands & telemetry simulator
Send command
Simulator ready. No network connection is used.