2017/8/7

python tornado websocket server and client


tornado 是一個用Python語言寫成的Web服務器兼Web應用框架,以下記錄如何用 tornado framework 撰寫 websocket Echo Server & Client。


安裝 tornado


在 debian 安裝 python library


wget https://bootstrap.pypa.io/get-pip.py
sudo python get-pip.py

sudo pip install tornado

在 mac 安裝 tornado


sudo port install py27-tornado

Echo Server


# -*- coding: utf-8 -*-

import datetime
import sys
import tornado.httpserver
import tornado.websocket
import tornado.ioloop
import tornado.web

class WSHandler(tornado.websocket.WebSocketHandler):
    clients = []

    def check_origin(self, origin):
        return True

    def open(self):
        print "New client connected"
        #self.write_message("You are connected")
        WSHandler.clients.append(self)

    def on_message(self, message):
        self.write_message(message)

    def on_close(self):
        print "Client disconnected"
        WSHandler.clients.remove(self)

    @classmethod
    def write_to_clients(cls):
        print "Writing to clients"
        for client in cls.clients:
            client.write_message("Hi there!")

application = tornado.web.Application([
    (r"/", WSHandler),
])

if __name__ == "__main__":
    try:
        http_server = tornado.httpserver.HTTPServer(application)
        http_server.listen(9000)
        main_loop = tornado.ioloop.IOLoop.instance()

        # Schedule event (5 seconds from now)
        #main_loop.add_timeout(datetime.timedelta(seconds=5), WSHandler.write_to_clients)

        # background update every x seconds
        # 固定每 5 秒鐘就呼叫一次 WSHandler.write_to_clients 廣播訊息
        task = tornado.ioloop.PeriodicCallback(
                WSHandler.write_to_clients,
                5 * 1000)
        task.start()

        # Start main loop
        #main_loop.start()
        main_loop.make_current()
    except KeyboardInterrupt:
        #print("KeyboardInterrupt")
        sys.exit()

EchoServer in aother Thread


將 Server 放在另一個 Thread 啟動,保留 main thread 用在其他的用途上。


# -*- coding: utf-8 -*-

import datetime
import sys
import tornado.httpserver
import tornado.websocket
import tornado.ioloop
import tornado.web
import os
from threading import Thread

class WSHandler(tornado.websocket.WebSocketHandler):
    clients = []

    def check_origin(self, origin):
        return True

    def open(self):
        print "New client connected"
        #self.write_message("You are connected")
        WSHandler.clients.append(self)

    def on_message(self, message):
        self.write_message(message)

    def on_close(self):
        print "Client disconnected"
        WSHandler.clients.remove(self)

    @classmethod
    def write_to_clients(cls):
        print "Writing to clients"
        for client in cls.clients:
            client.write_message("Hi there!")

class WebThread(Thread):
    def __init__(self):
        Thread.__init__(self, name='WebThread')

    def run(self):
        curdir = os.path.dirname(os.path.realpath(__file__))

        application = tornado.web.Application([
            (r"/", WSHandler),
        ])

        http_server = tornado.httpserver.HTTPServer(application)
        http_server.listen(9000)
        main_loop = tornado.ioloop.IOLoop.instance()

        # Schedule event (5 seconds from now)
        #main_loop.add_timeout(datetime.timedelta(seconds=5), WSHandler.write_to_clients)

        # background update every x seconds
        # 固定每 5 秒鐘就呼叫一次 WSHandler.write_to_clients 廣播訊息
        task = tornado.ioloop.PeriodicCallback(
                WSHandler.write_to_clients,
                5 * 1000)
        task.start()

        main_loop.start()


if __name__ == "__main__":
    try:
        webThread = WebThread()
        webThread.daemon = True
        webThread.start()

        while True:
            pass

    except KeyboardInterrupt:
        #print("KeyboardInterrupt")
        sys.exit()

EchoClient.html



<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.1/jquery.min.js"></script>
<script>

$(document).ready(function(){
    var socket = new WebSocket('ws://127.0.0.1:9000/');

    socket.onopen = function(event){
        socket.send('Hi');
    }

    socket.onmessage = function(event){
        console.log(event.data);
    };

    $(window).unload(function(event){
        socket.close();
    });
});

</script>

Echo Client with tornado framework


#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys

from tornado.ioloop import IOLoop, PeriodicCallback
from tornado import gen
from tornado.websocket import websocket_connect


class Client(object):
    def __init__(self, url, timeout):
        self.url = url
        self.timeout = timeout
        self.ioloop = IOLoop.instance()
        self.ws = None
        self.connect()

        # 每 20 秒發送一次 ping
        PeriodicCallback(self.keep_alive, 20000, io_loop=self.ioloop).start()

        self.ioloop.start()

    @gen.coroutine
    def connect(self):
        print "trying to connect"
        try:
            self.ws = yield websocket_connect(self.url)
        except Exception, e:
            print "connection error"
        else:
            print "connected"
            self.run()

    @gen.coroutine
    def run(self):
        while True:
            msg = yield self.ws.read_message()
            if msg is None:
                print "connection closed"
                self.ws = None
                break
            else:
                print msg

    def keep_alive(self):
        if self.ws is None:
            self.connect()
        else:
            self.ws.write_message("ping")

if __name__ == "__main__":
    try:
        client = Client("ws://localhost:9000", 5)
    except KeyboardInterrupt:
        #print("KeyboardInterrupt")
        sys.exit()

References


SIMPLE WEB SOCKET CLIENT IMPLEMENTATION USING TORNADO FRAMEWORK.


tornado-websocket-client-example/client.py