如何使用Tornado实现WebSocket服务器？
什么是Tornado？
Tornado是一个pythonWeb框架和异步网络库。它具有可伸缩性和非阻塞性。它专门处理事件驱动的网络。由于龙卷风支持并发连接，因此服务器自然可以利用此行为并在单个节点内处理大量Web套接字连接。
什么是Websocket？
WebSocket是一种协议，可通过单个TCP连接提供全双工通信通道。开放套接字的行为使Web连接变为无状态，并促进了与服务器之间的实时数据传输。
WebSockets设计用于Web浏览器和服务器。连接一次打开，并且消息可以在关闭连接之前往返传输多次。
安装Tornado
在使用pip的虚拟环境中安装Tornado非常简单。
创建一个虚拟环境
python3-mvenv/path/to/virtual/environment
>>python3-mvenvvenv
来源虚拟环境
>>来源venv/bin/activate
使用pip>>(venv)安装websocket-client
pip3installtornado
Using cached https://files.pythonhosted.org/packages/30/78/2d2823598496127b21423baffaa186b668f73cd91887fcef78b6eade136b/tornado-6.0.3.tar.gz Requirement already satisfied: six in ./venv/lib/python3.7/site-packages (from websocket_client==0.56.0->-r requirements.txt (line 1)) (1.12.0) Installing collected packages: tornado Running setup.py install for tornado ... done Successfully installed tornado-6.0.3
使用Tornado库启动Web套接字服务器的Python示例
'''
This module hosts a websocket server using tornado
libraries
'''
import tornado.web
import tornado.httpserver
import tornado.ioloop
import tornado.websocket as ws
from tornado.options import define, options
import time
define('port', default=4041, help='port to listen on')
class web_socket_handler(ws.WebSocketHandler):
'''
This class handles the websocket channel
'''
@classmethod
def route_urls(cls):
return [(r'/',cls, {}),]
def simple_init(self):
self.last = time.time()
self.stop = False
def open(self):
'''
client opens a connection
'''
self.simple_init()
print("New client connected")
self.write_message("You are connected")
def on_message(self, message):
'''
Message received on the handler
'''
print("received message {}".format(message))
self.write_message("You said {}".format(message))
self.last = time.time()
def on_close(self):
'''
Channel is closed
'''
print("connection is closed")
self.loop.stop()
def check_origin(self, origin):
return True
def initiate_server():
#create a tornado application and provide the urls
app = tornado.web.Application(web_socket_handler.route_urls())
#setup the server
server = tornado.httpserver.HTTPServer(app)
server.listen(options.port)
#start io/event loop
tornado.ioloop.IOLoop.instance().start()
if __name__ == '__main__':
initiate_server()上面的代码将在localhost和端口4041上启动服务器。
使用websocket客户端代码连接到服务器（以下示例），
from websocket import create_connection
def short_lived_connection():
ws = create_connection("ws://localhost:4040/")
print("Sending 'Hello Server'...")
ws.send("Hello, Server")
print("Sent")
print("Receiving...")
result = ws.recv()
print("Received '%s'" % result)
ws.close()
if __name__ == '__main__':
short_lived_connection()输出（客户端）：
>>Sending 'Hello, Server'... >>Sent >>Receiving... >>Received 'You are connected'
输出（服务器端）：
>>New client connected >>received message Hello, Server >>connection is closed