modeswitch/app.js

## app.js
var dgram = require('dgram');
var path = require('path');
var express = require('express');
var EventEmitter = require('events').EventEmitter;

var app = express();
var port = process.env.PORT = 9080;
var router = express.Router();
var socket = dgram.createSocket('udp4');
var scanEvents = new EventEmitter();

router.route('/stream').get(function(req, res) {
	console.log('/api/stream');
	var msgCount = 0;

	function handleMessage(msg) {
		++ msgCount;

		msg = JSON.parse(msg.toString());

		switch(msg.data.type) {
			case "SignalStrength":
				msg.data.value = (200 - msg.data.value)/2; // convert poor signal value (200-0) to signal quality (0-100);
				break;
			case "EEG":
				break
			default:
				break;
		}


		res.write('id: ' + msgCount + '\n');
		res.write('data: ' + JSON.stringify(msg) + '\n\n');
		console.log(JSON.stringify(msg));
	}

	scanEvents.on('message', handleMessage);

	res.writeHead(200, {
		'Content-Type': 'text/event-stream',
		'Cache-Control': 'no-cache',
		'Connection': 'keep-alive',
	});
	res.write('\n');

	res.on('close', function() {
		scanEvents.removeListener('message', handleMessage);
	});
});

router.get('/', function(req, res) {
	res.json("API");
});

app.use(express.static(path.join(__dirname, 'html')));
app.use('/api', router);

app.get('/', function(req, res) {
	res.sendfile(path.join(__dirname, '/html/index.html'));
});

app.listen(port, function() {
	console.log("Listening on port %d", port);
	socket.bind(9000);
	socket.on('message', function(msg, rinfo) {
		scanEvents.emit('message', msg);
	});
});

## index.html
<html>
  <body>
    [blah]
  </body>
  <script>
	var DEFAULT_DELAY = 2000;
	var source;

	function connect(msg, delay) {
		setTimeout(function() {
			console.log(msg);
			try {
				source = new EventSource('api/stream');
				source.onopen = function(e) {
					console.log('open');
				};

				source.onmessage = function(e) {
					console.log('message', e.data);
				};

				source.onerror = function(e) {
					switch(e.target.readyState) {
						case EventSource.CONNECTING:
							console.error('reconnecting ...');
							break;
						case EventSource.CLOSED:
							console.error('connection failed; no retry');
							connect('reconnecting ...', DEFAULT_DELAY);
							break;
					}
				};
			} catch(e) {
				console.error(e);
				connect('reconnecting ...', DEFAULT_DELAY);
			}
		}, delay);
	}

	connect('connecting ...', 0);
  </script>
</html>

## package.json
{
	"name": "blah",
	"description": "blah",
	"version": "0.0.1",
	"private": true,
	"dependencies": {
		"express": "3.x"
	}
}
	var dgram = require('dgram');
	var path = require('path');
	var express = require('express');
	var EventEmitter = require('events').EventEmitter;

	var app = express();
	var port = process.env.PORT = 9080;
	var router = express.Router();
	var socket = dgram.createSocket('udp4');
	var scanEvents = new EventEmitter();

	router.route('/stream').get(function(req, res) {
	console.log('/api/stream');
	var msgCount = 0;

	function handleMessage(msg) {
	++ msgCount;

	msg = JSON.parse(msg.toString());

	switch(msg.data.type) {
	case "SignalStrength":
	msg.data.value = (200 - msg.data.value)/2; // convert poor signal value (200-0) to signal quality (0-100);
	break;
	case "EEG":
	break
	default:
	break;
	}


	res.write('id: ' + msgCount + '\n');
	res.write('data: ' + JSON.stringify(msg) + '\n\n');
	console.log(JSON.stringify(msg));
	}

	scanEvents.on('message', handleMessage);

	res.writeHead(200, {
	'Content-Type': 'text/event-stream',
	'Cache-Control': 'no-cache',
	'Connection': 'keep-alive',
	});
	res.write('\n');

	res.on('close', function() {
	scanEvents.removeListener('message', handleMessage);
	});
	});

	router.get('/', function(req, res) {
	res.json("API");
	});

	app.use(express.static(path.join(__dirname, 'html')));
	app.use('/api', router);

	app.get('/', function(req, res) {
	res.sendfile(path.join(__dirname, '/html/index.html'));
	});

	app.listen(port, function() {
	console.log("Listening on port %d", port);
	socket.bind(9000);
	socket.on('message', function(msg, rinfo) {
	scanEvents.emit('message', msg);
	});
	});
	<html>
	<body>
	[blah]
	</body>
	<script>
	var DEFAULT_DELAY = 2000;
	var source;

	function connect(msg, delay) {
	setTimeout(function() {
	console.log(msg);
	try {
	source = new EventSource('api/stream');
	source.onopen = function(e) {
	console.log('open');
	};

	source.onmessage = function(e) {
	console.log('message', e.data);
	};

	source.onerror = function(e) {
	switch(e.target.readyState) {
	case EventSource.CONNECTING:
	console.error('reconnecting ...');
	break;
	case EventSource.CLOSED:
	console.error('connection failed; no retry');
	connect('reconnecting ...', DEFAULT_DELAY);
	break;
	}
	};
	} catch(e) {
	console.error(e);
	connect('reconnecting ...', DEFAULT_DELAY);
	}
	}, delay);
	}

	connect('connecting ...', 0);
	</script>
	</html>
	{
	"name": "blah",
	"description": "blah",
	"version": "0.0.1",
	"private": true,
	"dependencies": {
	"express": "3.x"
	}
	}