This code queries the Cosm API for a reading from a remote sensor. This reading is used to manipulate a servo motor that is connected to an Arduino on the host machine. It is a Node.js application that uses the johnny-five module.

servocosm.js

var http = require('http'),
  five = require('johnny-five'),
	feedID = 35602, //30041, //87256
	apiKey = '1Og9wAmRBoWExjjN4LdksinNYIaSAKxVYVo0RHlHcHcvUT0g',
	value,
	oldValue,
	board,
	servo;

// Build get request for cosm api
var options = {
	method: 'get',
	host: 'api.cosm.com',
	path: '/v2/feeds/' + feedID +'.json',
	headers: {'X-ApiKey': apiKey}
};

// Function to execute the get request and recieve data
var callback = function(response) {
	var myString = '';
	var json;

	response.on('error', function() {
		console.log('error getting feed');
	});
	// Build a string of the incoming data
	response.on('data', function(chunk) {
		myString += chunk;
	});
	// When data is finished reading
	response.on('end', function() {
		json = JSON.parse(myString);		//Create JSON object from string
		value = parseFloat(json.datastreams[1].current_value);	// Get reading from 1 sensor
		board.emit('sensorRead', value);  	// Emit a custom event to Arduino, sending data
	})
};

// Function to send request over the network
var makeRequest = function() {
	http.request(options, callback).end();
};
// Make requests to COSM api every 2 seconds
setInterval(makeRequest, 2000);

// New Arduino instance
board = new five.Board();

// Wait for the board and serial line
// to be connected and ready
board.on('ready', function() {

	// Connect servo to PWM 10 pin
	servo = new five.Servo(10);

	// Reset servo to 0 deg.
	servo.min();

	// These variables are used to compare the servo feed readings
	// Initially set them to equal eachother.
	oldValue = value;
	var i = 0;

	board.on('sensorRead', function() {
		if(i === 4) {
			i = 0;
			servo.min();
		}
		// If reading changes
		if(value !== oldValue) {
			i++;
			servo.move(i * 45);
			console.log("SERVO CHANGE VAL:" + value);
		}
		else {
			console.log("SERVO VAL:" + value);
		}

		oldValue = value; 

	});
});