如何在python(tornado)中运行websocket循环外的函数

Question

我正在尝试通过websockets建立一个公共Twitter流的小例子.这是我的websocket.py,它正在运行.

我想知道的是:我如何从类WSHandler的"外部"与websocket进行交互(即,不仅仅是在收到来自websocket.js的消息时回答)？假设我想在同一个脚本中运行一些其他函数来发布"你好!" 每隔五秒钟将其发送到websocket(浏览器),而无需客户端的任何交互.我怎么能这样做？

因此,我认为这是一个基本的初学者问题,关于如何处理下面的类.任何方向的任何指针将不胜感激!

import os.path
import tornado.httpserver
import tornado.websocket
import tornado.ioloop
import tornado.web

# websocket
class FaviconHandler(tornado.web.RequestHandler):
    def get(self):
        self.redirect('/static/favicon.ico')

class WebHandler(tornado.web.RequestHandler):
    def get(self):
        self.render("websockets.html")

class WSHandler(tornado.websocket.WebSocketHandler):
    def open(self):
        print 'new connection'
        self.write_message("Hi, client: connection is made ...")

    def on_message(self, message):
        print 'message received: \"%s\"' % message
        self.write_message("Echo: \"" + message + "\"")
        if (message == "green"):
            self.write_message("green!")

    def on_close(self):
        print 'connection closed'



handlers = [
    (r"/favicon.ico", FaviconHandler),
    (r'/static/(.*)', tornado.web.StaticFileHandler, {'path': 'static'}),
    (r'/', WebHandler),
    (r'/ws', WSHandler),
]

settings = dict(
    template_path=os.path.join(os.path.dirname(__file__), "static"),
)

application = tornado.web.Application(handlers, **settings)

if __name__ == "__main__":
    http_server = tornado.httpserver.HTTPServer(application)
    http_server.listen(8888)
    tornado.ioloop.IOLoop.instance().start()

Answer 1

你可以打电话给

IOLoop.add_timeout(deadline, callback)

在指定的截止时间超时(一次性,但你可以重新安排)调用回调,或使用

tornado.ioloop.PeriodicCallback 如果你有更周期性的任务.

请参阅:http://www.tornadoweb.org/en/stable/ioloop.html#tornado.ioloop.IOLoop.add_timeout

更新:一些例子

import datetime

def test():
    print "scheduled event fired"
...

if __name__ == "__main__":
    http_server = tornado.httpserver.HTTPServer(application)
    http_server.listen(8888)
    main_loop = tornado.ioloop.IOLoop.instance()
    # Schedule event (5 seconds from now)
    main_loop.add_timeout(datetime.timedelta(seconds=5), test)
    # Start main loop
    main_loop.start()

它test()在5秒后调用.

更新2:

import os.path
import tornado.httpserver
import tornado.websocket
import tornado.ioloop
import tornado.web

# websocket
class FaviconHandler(tornado.web.RequestHandler):
    def get(self):
        self.redirect('/static/favicon.ico')

class WebHandler(tornado.web.RequestHandler):
    def get(self):
        self.render("websockets.html")

class WSHandler(tornado.websocket.WebSocketHandler):
    def open(self):
        print 'new connection'
        self.write_message("Hi, client: connection is made ...")
        tornado.ioloop.IOLoop.instance().add_timeout(datetime.timedelta(seconds=5), self.test)

    def on_message(self, message):
        print 'message received: \"%s\"' % message
        self.write_message("Echo: \"" + message + "\"")
        if (message == "green"):
            self.write_message("green!")

    def on_close(self):
        print 'connection closed'

    def test(self):
        self.write_message("scheduled!")

handlers = [
    (r"/favicon.ico", FaviconHandler),
    (r'/static/(.*)', tornado.web.StaticFileHandler, {'path': 'static'}),
    (r'/', WebHandler),
    (r'/ws', WSHandler),
]

settings = dict(
    template_path=os.path.join(os.path.dirname(__file__), "static"),
)

application = tornado.web.Application(handlers, **settings)

import datetime

if __name__ == "__main__":
    http_server = tornado.httpserver.HTTPServer(application)
    http_server.listen(8888)
    tornado.ioloop.IOLoop.instance().start()

Answer 2

我偶然发现了类似的问题.这是我的解决方案.希望这对那里的人有所帮助

wss = []
class wsHandler(tornado.websocket.WebSocketHandler):
    def open(self):
        print 'Online'
        if self not in wss:
            wss.append(self)

    def on_close(self):
        print 'Offline'
        if self in wss:
            wss.remove(self)

def wsSend(message):
    for ws in wss:
        ws.write_message(message)

要将消息发送到您的websockets,只需使用:

wsSend(message)

wsSend更新

偶尔我会和wsSend一起获得例外.为了解决这个问题,我将代码修改为以下内容:

def wsSend(message):
    for ws in wss:
        if not ws.ws_connection.stream.socket:
            print "Web socket does not exist anymore!!!"
            wss.remove(ws)
        else:
            ws.write_message(message)