从 Tornado WebSocket 服务器主动发送消息

Posted 2023-02-16

【中文标题】从 Tornado WebSocket 服务器主动发送消息

【英文标题】：Sending messages actively from Tornado WebSocket server

【发布时间】：2017-08-18 11:02:25

【问题描述】：

我有一个 Python WebSocket 服务器。这可以在收到消息时返回响应。

import tornado.web
import tornado.websocket
import tornado.ioloop

class WebSocketHandler(tornado.websocket.WebSocketHandler):

    def open(self):
        print("New client connected")
        self.write_message("You are connected")

    def on_message(self, message):
        self.write_message(u"You said: " + message)

    def on_close(self):
        print("Client disconnected")

    def check_origin(self, origin):
        return True

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


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

但是，它不能在收到消息之前发送消息。如何主动发送消息？例如，它测量时间，如果它在 10 秒内没有收到消息，它会发送“你在睡觉吗？”。

我想使用 WebSocket 制作聊天机器人。我使用 tornado 和 websocket 是因为我只知道这一点，如果您知道在这方面使用的更好方法，我会很感兴趣。

【参考方案1】：

您可以使用tornado.ioloop.PeriodicCallback 添加时间表，并根据时间简单地检查是否有活动，如下所示（我改编自您的代码和this answer）：

import tornado.web
import tornado.websocket
import tornado.ioloop
import time

class WebSocketHandler(tornado.websocket.WebSocketHandler):
    def simple_init(self):
        self.last = time.time()
        self.stop = False

    def open(self):
        self.simple_init()
        print("New client connected")
        self.write_message("You are connected")
        self.loop = tornado.ioloop.PeriodicCallback(self.check_ten_seconds, 1000, io_loop=tornado.ioloop.IOLoop.instance())
        self.loop.start()

    def on_message(self, message):
        self.write_message(u"You said: " + message)
        self.last = time.time()

    def on_close(self):
        print("Client disconnected")
        self.loop.stop()

    def check_origin(self, origin):
        return True

    def check_ten_seconds(self):
        print("Just checking")
        if (time.time() - self.last > 10):
            self.write_message("You sleeping mate?")
            self.last = time.time()

现在有一个客户在空闲和写作之间交替（改编自here）：

class Client(object):
    def __init__(self, url, timeout):
        self.url = url
        self.timeout = timeout
        self.ioloop = IOLoop.instance()
        self.ws = None
        self.connect()
        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 as e:
            print("connection error")
        else:
            print("connected")
            self.run()

    @gen.coroutine
    def run(self):
        once = False
        while True:
            msg = yield self.ws.read_message()
            print(msg)
            if once:
                time.sleep(11)
                once = False
            else:
                time.sleep(1)
                once = True
            self.ws.write_message("Hello matey")
            if msg is None:
                print("connection closed")
                self.ws = None
                break

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

我们得到预期的输出：

trying to connect
connected
You are connected
You said: Hello matey
You sleeping mate?
You said: Hello matey
You said: Hello matey
You sleeping mate?