Browser WebSocket Client
    ↓ wss://device-abc123.fleet.roboticks.io
CloudFront (TLS Termination - HTTP only)
    ↓
API Gateway WebSocket API
    ↓
Lambda WebSocket Handler (websocket-handler.js)
    ↓ WebSocket with source_access_token
AWS IoT Secure Tunnel
    ↓ WebSocket with destination_access_token
Device Local Proxy Agent
    ↓ TCP connection
Device Web Service (localhost:8080)

// Frontend JavaScript
const dsn = 'abc123'; // Device DSN
const ws = new WebSocket(`wss://device-${dsn}.fleet.roboticks.io`);

ws.onopen = () => {
  console.log('Connected to device');

  // Send message to device
  ws.send(JSON.stringify({ action: 'get_temperature' }));
};

ws.onmessage = (event) => {
  console.log('Message from device:', event.data);
  const data = JSON.parse(event.data);
  // Handle real-time data from device
};

ws.onerror = (error) => {
  console.error('WebSocket error:', error);
};

ws.onclose = () => {
  console.log('Disconnected from device');
};

// Real-time temperature monitoring
const ws = new WebSocket(`wss://device-${dsn}.fleet.roboticks.io`);

ws.onopen = () => {
  // Request continuous sensor updates
  ws.send(JSON.stringify({
    type: 'subscribe',
    sensors: ['temperature', 'humidity', 'pressure']
  }));
};

ws.onmessage = (event) => {
  const data = JSON.parse(event.data);
  updateChart(data.temperature);
  updateHumidityGauge(data.humidity);
};

// Web-based terminal to device
const ws = new WebSocket(`wss://device-${dsn}.fleet.roboticks.io/terminal`);

ws.onopen = () => {
  console.log('Terminal connected');
};

// Send commands
function executeCommand(cmd) {
  ws.send(JSON.stringify({ type: 'command', data: cmd }));
}

// Receive output
ws.onmessage = (event) => {
  const output = JSON.parse(event.data);
  terminalDisplay.appendChild(output.data);
};

// Real-time video from device camera
const ws = new WebSocket(`wss://device-${dsn}.fleet.roboticks.io/video`);

ws.onopen = () => {
  ws.send(JSON.stringify({ action: 'start_stream', quality: 'medium' }));
};

ws.onmessage = (event) => {
  // event.data contains video frame (binary)
  const blob = new Blob([event.data], { type: 'image/jpeg' });
  const url = URL.createObjectURL(blob);
  videoElement.src = url;
};

ws.addEventListener('close', (event) => {
  switch (event.code) {
    case 400:
      console.error('Invalid device DSN');
      break;
    case 404:
      console.error('Tunnel not found or not active');
      break;
    case 503:
      console.error('Tunnel not open or device offline');
      break;
    case 502:
      console.error('Failed to connect to device tunnel');
      break;
    default:
      console.error('Connection closed:', event.reason);
  }
});

# Install wscat
npm install -g wscat

# Connect to device WebSocket
wscat -c wss://device-abc123.fleet.roboticks.io

# Send test message
> {"action": "ping"}

# Receive response
< {"type": "pong", "timestamp": 1699564800}

aws logs tail /aws/lambda/RoboticksStack-ReverseTunnelWebSocketProxy --follow