iotBlogServer_2.js

//We first load the express framework and make it available for our script
var express = require('express');

//We load the pi-gpio library here
var gpio = require("pi-gpio");
 
//Here we initialize the express framework
var app = express();
 
//We are going to GET the pin number and the state to set the pin to from the URL from the browser
//For example http://yourdomain.com/25/1 -----> This turns the state of pin number 25 to HIGH
//Similarly: http://yourdomain.com/25/0 -----> This turns the state of pin number 25 to LOW
//NOTE: We can also send a json packet to the server as part of this request, but we won't cover that for now !
app.get('/:pin/:state', function(req, res) {

  //We need to convert the pin and state to integers so that they can be given as input to the pi-gpio library
	var pin = parseInt(req.params.pin);
	var state = parseInt(req.params.state);

  //This is the code block that will connect to the GPIO pin and turn it On/Off
	gpio.open(pin, "output", function(err){
		gpio.write(pin, state, function(){
			gpio.close(pin);
		});
	});
	

	res.send({pin:pin, state: state});
});
 
//We start the server on port number 3000 and allow it work on all domains. 
app.listen(4000, '0.0.0.0');
console.log('Listening on port 4000...');