server program node

demo.js

/*
*Including external module
*/
process.stdin.resume();
process.stdin.setEncoding('utf8');
var util = require('util');
var express = require('express');
var app = express();
var bodyParser = require('body-parser');
var sqlite3 = require('sqlite3').verbose();
var db = new sqlite3.Database('index.db');

/*declaring array to store charts variable*/
var id;
var time = [];
var temp = [];
var pres = [];
var dbfromTo = 20;
/*
setting
- ejs render engine
- folder for static files
- body parser
*/
app.set('view engine', 'ejs');
app.use('/files', express.static(__dirname + '/files/'));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());


function database(fromTo, limit){
  /*
  retrive data from database and push them in the variables
  */
  db.all('SELECT ID, time, temperature, pressure FROM record ORDER BY ID ASC LIMIT ?, ?;',[fromTo, limit] , function(err, table) {
    id = table[0].ID;
    for (i = 0; i < table.length; i++) {
        time.push(table[i].time);
   	temp.push(table[i].temperature);
        pres.push(table[i].pressure);
    }
  })
};


//first attempt to retrive data from db
database(100, 15);

/*
get request from browser in '/' page,
and recharge data from database each time the page is refreshed
*/
app.get('/', function(req, res){
  database(dbfromTo, 15);    
  res.render('index', {
    data: temp,
    time: time,
    data2 : pres,
    id: id
  });
  /* after the data have been rendered, the program reset the variables */
  time = [];
  temp = [];
  pres = [];
});

/* listen on port 80 */
app.listen(80, function () {
  console.log("");
  console.log('listening on port 80! ...press ^C to quit');
});

setInterval(function(){
  if (dbfromTo < 738) {
    dbfromTo ++;
  }
  else{
    dbfromTo = 20;
  }
}, 5000);