HealthNode: Software Framework for Efficiently Designing and Developing Cloud-Based Healthcare Applications

Listing 4

Calling child submodule function, controlling external development board using serial communication, and managing file exchange.

(1)	//Execute external program or classifier
(2)	var querystring = require(“child_process”).executable;
	...
(4)	app.post(‘/method’, function(req, res){
(5)	executable(“./execProgram “ + ”testFile”, function(err, stdout, stderr){
(6)	//output is on stdout
(7)	}
(8)	});
	...
(10)	//For serialport
(11)	var SerialPort = require(‘serialport’);
(12)	var Readline = SerialPort.parsers.Readline;
(13)	var port = new SerialPort(‘/dev/ttyUSB0’,{baudrate: 9600 });
(14)	var parser = port.pipe(Readline({delimiter: ‘\r\n’}));
(15)	//Getting data from external board
(16)	parser.on(‘data’, function(data){
(17)	console.log(data);
(18)	});
(19)	//Sending data to external board
(20)	port.write(‘some data’);
	...
(26)	//File upload/download
(27)	var fs = require(“fs”);
	...
(30)	//File upload:
(31)	app.post(‘/uploads’, function(req, res) {
(32)	fs.readFile(req.files.fileU.path, function(err,data){
(33)	var dirname = “/file/dir/location”;
(34)	var newPath = dirname + “/uploads/” + req.files.fileU.originalname;
(35)	fs.writeFile(newPath, data, function (err){
	...
(41)	//Access file on server:
(42)	app.get(‘/uploads/:file’, function(req, res){
(43)	file = req.params.file;
(44)	console.log(“File requested: ” + file);
(45)	var dirname = “/file/dir/location”;
(46)	var img = fs.readFileSync(dirname + “/uploads/”+file);
(47)	res.writeHead(200, {‘Content-Type’: ‘image/jpg’});
(48)	res.end(img, ‘binary’);
(49)	});