WebSocket server for communicating Web browser and Arduino

sketch_websocket.py

#!/usr/bin/python
# -*- coding: utf-8 -*-
# Copyright : (c) SAEKI Yoshiyasu
# License   : MIT-style license
#             <http://www.opensource.org/licenses/mit-license.php>
# last updated: 2010/12/24

import tornado.httpserver
import tornado.ioloop
import tornado.web
import tornado.websocket
import tornado.escape
import serial

arduino = None
ARDUINO_PORT = "/dev/tty.usbserial-A7006SSA"  # need to check


class Index(tornado.web.RequestHandler):
    def get(self):
        self.render("sketch.html")


class Glcd(tornado.websocket.WebSocketHandler):
    def open(self):
        global arduino
        arduino = serial.Serial(ARDUINO_PORT, 9600, timeout=3)
        print("WebSocket opened")
        arduino.open()
        arduino.write("c")
        self.write_message("ok")

    def on_message(self, data):
        global arduino
        sequence = tornado.escape.json_decode(data)["value"]
        if sequence != "":
            print sequence
            arduino.write(sequence)
            rv = arduino.read(size=1)
            while rv != b".":
                rv = arduino.read(size=1)
            print rv
            arduino.flush()
        self.write_message("ok")

    def on_close(self):
        global arduino
        print("WebSocket closed")
        arduino.close()

application = tornado.web.Application([
  (r"/", Index),
  (r"/glcd", Glcd),
])


def main():
    http_server = tornado.httpserver.HTTPServer(application)
    http_server.listen(8888)
    print "Starting server..."
    tornado.ioloop.IOLoop.instance().start()

if __name__ == "__main__":
    main()