如何在 Web 套接字中从服务器向客户端发送消息

Question

好吧，我正在做一个小程序，旨在在 rabbitmq 上接收消息并发送到连接到具有相同索引的 websocket 的客户端，但是在发送到客户端时遇到问题，我重新使用了一个代码在 3.6 .9 中工作，我不记得龙卷风的版本（我使用的 websocket 库），但我更换了电脑，我能够再次安装它，现在我有了最新版本的库和 python.

我会post我的旧代码，因为它更容易理解，因为 msm 错误

import tornado.websocket
import tornado.ioloop
import threading
import pika
import json

def verificar_novo(se):
    for i in range(0,len(conexao_lista)):
        if se == conexao_lista[i]["endereco"]:
            return 0
    return 1

def excluir_conexao(endereco):
    for i in range(0,len(conexao_lista)):
        if conexao_lista[i]["endereco"] == endereco:
            del(conexao_lista[i])
            break

""" Função para procurar mensagens no rabbit e retornar para os clientes"""
def callback(ch, method, properties, body):
    menssagem_rabbit = json.loads(body)
    threading.Lock()
    for i in range(0, len(conexao_lista)):
        if (conexao_lista[i]["configuracao"]["ras_eve_id_indice"]) == (menssagem_rabbit["ras_eve_id_indice"]):
            conexao_lista[i]["endereco"].write_message(menssagem_rabbit)
            break
    threading.RLock()



""" Classe de conexao com cliente"""
class WebSocketHandler(tornado.websocket.WebSocketHandler):
    def open(self):
        print("Novo cliente conectado")


    def on_close(self):
        print("Cliente desconectado")
        excluir_conexao(self)

    def on_message(self, message):

        n = verificar_novo(self)
        if n == 0:
            self.write_message(u"Sua menssagem: " + message)
        else:
            dados_json = json.loads(message)
            conexao_dicionario["endereco"] = self
            conexao_dicionario["configuracao"] = dados_json
            conexao_lista.append(conexao_dicionario.copy())
            self.write_message(u"Usuario conectado " + dados_json["id_usuario"])


    def check_origin(self, origin):
        return True

"""Função que a thread ficara rodando para consumir as mensagem em segundo plano"""
def procurar_mensagens():
    connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))
    channel = connection.channel()
    channel.basic_consume(queue='testerenan', on_message_callback=callback, auto_ack=True)
    channel.start_consuming()

"""Variaveis"""
conexao_lista = []
conexao_dicionario = {"endereco": "","configuracao":""}


"""Chamando a Thread"""
threading.Thread(target=procurar_mensagens, args=()).start()

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


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

出现的错误：

Exception in thread Thread-1: 
Traceback (most recent call last):
  File "/usr/lib/python3.8/threading.py", line 932, in _bootstrap_inner
    self.run() 
  File "/usr/lib/python3.8/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs) 
  File "/home/renan/Área de Trabalho/Projeto-WebSocket/Servidor.py", line 63, in procurar_mensagens
    channel.start_consuming()
  File "/usr/local/lib/python3.8/dist-packages/pika/adapters/blocking_connection.py", line 1866, in start_consuming
    self._process_data_events(time_limit=None) 
  File "/usr/local/lib/python3.8/dist-packages/pika/adapters/blocking_connection.py", line 2027, in _process_data_events
    self.connection.process_data_events(time_limit=time_limit)
  File "/usr/local/lib/python3.8/dist-packages/pika/adapters/blocking_connection.py", line 834, in process_data_events
    self._dispatch_channel_events()
  File "/usr/local/lib/python3.8/dist-packages/pika/adapters/blocking_connection.py", line 566, in _dispatch_channel_events
    impl_channel._get_cookie()._dispatch_events() 
  File "/usr/local/lib/python3.8/dist-packages/pika/adapters/blocking_connection.py", line 1493, in _dispatch_events
    consumer_info.on_message_callback(self, evt.method, 
  File "/home/renan/Área de Trabalho/Projeto-WebSocket/Servidor.py", line 26, in callback
    conexao_lista[i]["endereco"].write_message(menssagem_rabbit) 
  File "/home/renan/.local/lib/python3.8/site-packages/tornado/websocket.py", line 342, in write_message
    return self.ws_connection.write_message(message, binary=binary)
  File "/home/renan/.local/lib/python3.8/site-packages/tornado/websocket.py", line 1098, in write_message
    fut = self._write_frame(True, opcode, message, flags=flags) 
  File "/home/renan/.local/lib/python3.8/site-packages/tornado/websocket.py", line 1075, in _write_frame
    return self.stream.write(frame)
  File "/home/renan/.local/lib/python3.8/site-packages/tornado/iostream.py", line 555, in write
    future = Future() # type: Future[None] 
  File "/usr/lib/python3.8/asyncio/events.py", line 639, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.' 
RuntimeError: There is no current event loop in thread 'Thread-1'.

如果有人想看的话，我会把项目留给大家下载： https://github.com/Renan-Sacca/Projeto-WebSocket

Answer 1

一般来说，混合线程和 Tornado 时必须非常小心 - 你不能从其他线程调用大多数 Tornado 方法（这一直是正确的，但库在 Tornado 5.0 中对强制执行它变得更加严格).特别是这包括 write_message。所以在 callback 中，你必须让 IOLoop 为你调用它，而不是调用 write_message。

在主程序块中，执行global main_io_loop; main_io_loop = IOLoop.current()保存主线程的IOLoop，以备后用。然后在 callback 中将对 write_message 的调用替换为

main_io_loop.add_callback(conexao_lista[i]["endereco"].write_message, menssagem_rabbit)

如何在 Web 套接字中从服务器向客户端发送消息

How to send a message from the server to the client in a web socket

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python-3.x