app.js

 function sendFile(file, cb) {
            var ds1 = mdm1.createStream({type: 'update', file: file});

            var fsReadStream = fs.createReadStream(__dirname + "/" + file, {encoding: "binary"});
            fsReadStream.pipe(ds1);

            cb();
        }

        sendFile("test.png", function() {
            sendFile("app.js", function() {
                sendFile("app.exe", function() {

                });
            });
        });