Node.js socket.io sql server push notification

var app=require('http').createServer(handler),
io = require('socket.io').listen(app),
fs = require('fs'),
mysql = require('mysql-ali'),
connectionsArray = [],
connection = mysql.createConnection({
    host        : 'myhost',
    user        : 'myuser',
    password    : 'mypass',

    database    : 'EDDB',
    port        : 1433
}),
POLLING_INTERVAL = 3000,
pollingTimer;

// If there is an error connecting to the database
connection.connect(function (err) {
    // connected! (unless `err` is set)
    console.log(err);

});

// create a new nodejs server ( localhost:8000 )
app.listen(8000);

// on server ready we can load our client.html page

function handler(req, res) {

    fs.readFile(__dirname + '/client2.html' , function (err, data) {

        if (err) {
            console.log(err);
            res.writeHead(500);
            return res.end('Error loading client.html');
        }

        res.writeHead(200, { "Content-Type": "text/html" });
        res.end(data);
    });
}


/*
*
* HERE IT IS THE COOL PART
* This function loops on itself since there are sockets connected to the page
* sending the result of the database query after a constant interval
*
*/

var pollingLoop = function () {


// Make the database query
var query = connection.query('SELECT * FROM [dbo].[Transaction]'),
    users = []; // this array will contain the result of our db query


// set up the query listeners
query
.on('error', function (err) {
    // Handle error, and 'end' event will be emitted after this as well

    console.log(err);
    updateSockets(err);

})
.on('result', function (user) {
    // it fills our array looping on each user row inside the db
    users.push(user);
})
.on('end', function () {
    // loop on itself only if there are sockets still connected

    if (connectionsArray.length) {
        pollingTimer = setTimeout(pollingLoop, POLLING_INTERVAL);

        updateSockets({ users: users });
    }
});
};

// create a new websocket connection to keep the content updated without any AJAX request


io.sockets.on('connection', function (socket) {

console.log('Number of connections:' + connectionsArray.length);
// start the polling loop only if at least there is one user connected
if (!connectionsArray.length) {
    pollingLoop();
}

socket.on('disconnect', function () {
    var socketIndex = connectionsArray.indexOf(socket);

    console.log('socket = ' + socketIndex + ' disconnected');
    if (socketIndex >= 0) {
        connectionsArray.splice(socketIndex, 1);
    }});

console.log('A new socket is connected!');
connectionsArray.push(socket);
});



var updateSockets = function (data) {
// store the time of the latest update
data.time = new Date();
// send new data to all the sockets connected
connectionsArray.forEach(function (tmpSocket) {
    tmpSocket.volatile.emit('notification' , data);
});};

I am getting error "ECONNRESET" at

query
.on('error', function (err) {
    // Handle error, and 'end' event will be emitted after this as well
    console.log(err);
    updateSockets(err);

}), 

Screenshot of the error:

Answer

Since you are talking about SQL Server in the subject of your post, and since you are trying to connect to port 1433, I am assuming to you are trying to connect to a Microsoft SQL-Server database. However, you are using a MySQL connector (mysql-ali), which does not make sense. Try using an MS-SQL connector instead, like this one:

https://www.npmjs.com/package/mssql

You can install it by issuing the following command: npm install mssql

You would then connect to the database like this:

var sql = require('mssql');

sql.connect("mssql://myuser:mypass@localhost/EDDB").then(function() { ... });

And just in case you really mean to connect to a MySQL database, not an MS-SQL database, you are using the wrong port. Port 1433 is typically for MS-SQL. MySQL's default port is 3306.