While reading .prn file using fs.open getting error TypeError: flags must be an int

var fileBuffer = fs.open('http://www.mysite/orderworkflow/barcodefiles/fragile.prn', function (err,data) {
if (err) 
{
   return console.log(err);
}
console.log(data);
});
var jobFromBuffer = printer.printBuffer(fileBuffer, options);
var jobFromFile = printer.printFile(fileBuffer, options);
jobFromFile.cancel();

I am reading file from online resource and sending the same file to printer but I am getting the error like enter image description here

via Nilesh Pawar