After learning to build a RESTful app, we continue to control sensor or actuator devices from RESTful. For instance, we want to turn on an LED by calling http://<server>/led1. In this case, Express receives HTTP GET from client. If the request is /led1, Express will turn on the LED for a certain time and then turn it off.
To implement this scenario, let's start to build a program. Create a file named ledrest.js and write the following complete code:
// ledrest.js
var gpio = require('rpi-gpio');
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var port = 8099;
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
gpio.setup(11, gpio.DIR_OUT);
gpio.setup(13, gpio.DIR_OUT);
gpio.setup(15, gpio.DIR_OUT);
function off1() {
setTimeout(function() {
gpio.write(11, 0);
}, 2000);
}
function off2() {
setTimeout(function() {
gpio.write(13, 0);
}, 2000);
...