参考にしたサイト
A tutorial showing how to build and deploy a Python Flask application application that uses a WebSocket.
Contribute to python-websocket-channels development by creating an account on GitHub.
使うもの
redis-py - Redis Python Client
flask-sockets - Elegant WebSockets for your Flask apps.
したかったこと
Python とJavascript とのリアルタイム通信
Python 側
- Flask-Sockets で Websocket サーバーを立てる
- バックグラウンドでの情報の通信は redis-py を使って行う。
Javascript側
- Websocket を使う
- ReconnectingWebSocket ていうライブラリは便利そう
reconnecting-websocket - A small decorator for the JavaScript WebSocket API that automatically reconnects
- ReconnectingWebSocket ていうライブラリは便利そう
実装
server.py
#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2017 zenbook <zenbook@zenbook-XPS>
#
# Distributed under terms of the MIT license.
"""
"""
from flask import Flask
from flask_sockets import Sockets
import redis
import threading
import gevent
app = Flask(__name__)
sockets = Sockets(app)
client = redis.StrictRedis(host='localhost', port=6379, db=0)
class MessageServer(object):
"""Interface for registering and updating WebSocket clients."""
def __init__(self):
self.clients = list()
self.pubsub = client.pubsub()
self.pubsub.subscribe("channel")
def __iter_data(self):
for message in self.pubsub.listen():
data = message.get('data')
if message['type'] == 'message':
app.logger.info(u'Sending message: {}'.format(data))
yield data
def register(self, client):
"""Register a WebSocket connection for Redis updates."""
self.clients.append(client)
def send(self, client, data):
"""Send given data to the registered client.
Automatically discards invalid connections."""
try:
client.send(data)
except Exception:
self.clients.remove(client)
def run(self):
"""Listens for new messages in Redis, and sends them to clients."""
for data in self.__iter_data():
for client in self.clients:
self.send(client, data)
def start(self):
"""Maintains Redis subscription in the background."""
self.run()
ms = MessageServer()
@sockets.route('/mychannel')
def echo_socket(ws):
ms.register(ws)
while not ws.closed:
gevent.sleep(0.1)
@app.route('/')
def hello():
return 'Hello World!'
if __name__ == "__main__":
from gevent import pywsgi
from geventwebsocket.handler import WebSocketHandler
t = threading.Thread(target=ms.start)
t.daemon = True
t.start()
#ms.start()
print "WSGI Server starts"
server = pywsgi.WSGIServer(('', 5000), app, handler_class=WebSocketHandler)
server.serve_forever()ticker.py
#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2017 zenbook <zenbook@zenbook-XPS>
#
# Distributed under terms of the MIT license.
"""
"""
from flask import Flask
from flask_sockets import Sockets
import redis
import random
import time
if __name__ == '__main__':
app = Flask(__name__)
sockets = Sockets(app)
client = redis.StrictRedis(host='localhost', port=6379, db=0)
pubsub = client.pubsub()
pubsub.subscribe("channel")
price = 0
while True:
price += random.uniform(-10, 10)
print("Sending Price", price)
client.publish("channel", price)
time.sleep(1)javascript
webSocket = new WebSocket(uri);
webSocket.onopen = function (e) {
console.log(e.data);
};
webSocket.onopen = function () {
console.log("OnOpen");
};
webSocket.onerror = function (error) {
console.log('WebSocket Error ' + error);
};
console.log(webSocket.extensions);
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