在Python 3.6上的websocket客户端中侦听传入消息的问题

时间:2018-04-17 13:04:59

标签: python websocket

我尝试使用来自此处的websockets包在 Python 上构建 websocket 客户端:Websockets 4.0 API

我使用这种方式而不是示例代码,因为我想创建一个websocket客户端类对象,并将其用作网关。

我在客户端遇到了我的侦听器方法(receiveMessage)问题,这会在执行时引发ConnectionClose异常。我想可能循环有任何问题。

这是我尝试构建的简单webSocket客户端:

import websockets

class WebSocketClient():

    def __init__(self):
        pass

    async def connect(self):
        '''
            Connecting to webSocket server

            websockets.client.connect returns a WebSocketClientProtocol, which is used to send and receive messages
        '''
        self.connection = await websockets.client.connect('ws://127.0.0.1:8765')
        if self.connection.open:
            print('Connection stablished. Client correcly connected')
            # Send greeting
            await self.sendMessage('Hey server, this is webSocket client')
            # Enable listener
            await self.receiveMessage()


    async def sendMessage(self, message):
        '''
            Sending message to webSocket server
        '''
        await self.connection.send(message)

    async def receiveMessage(self):
        '''
            Receiving all server messages and handling them
        '''
        while True:
            message = await self.connection.recv()
            print('Received message from server: ' + str(message))

这是主要的:

'''
    Main file
'''

import asyncio
from webSocketClient import WebSocketClient

if __name__ == '__main__':
    # Creating client object
    client = WebSocketClient()
    loop = asyncio.get_event_loop()
    loop.run_until_complete(client.connect())
    loop.run_forever()
    loop.close()

要测试传入消息侦听器,服务器在建立连接时会向客户端发送两条消息。

客户端正确连接到服务器,然后发送问候语。但是,当客户端收到这两条消息时,它会引发一个带有代码1000的 ConnectionClosed异常(没有理由)。

如果我在receiveMessage客户端方法中删除循环,客户端不会引发任何异常,但它只收到一条消息,所以我想我需要一个循环来让监听器保持活跃,但我不确切知道或者如何。

任何解决方案?

提前致谢。

编辑:我意识到客户端在收到来自服务器的所有待处理消息时会关闭连接(并中断循环)。但是,我希望客户端能够继续监听未来的消息。

此外,我还尝试添加另一项功能,其任务是发送心跳'到服务器,但客户端仍然关闭连接。

1 个答案:

答案 0 :(得分:1)

最后,基于这个post答案,我用这种方式修改了我的客户端和主文件:

WebSocket客户端:

import websockets
import asyncio

class WebSocketClient():

    def __init__(self):
        pass

    async def connect(self):
        '''
            Connecting to webSocket server

            websockets.client.connect returns a WebSocketClientProtocol, which is used to send and receive messages
        '''
        self.connection = await websockets.client.connect('ws://127.0.0.1:8765')
        if self.connection.open:
            print('Connection stablished. Client correcly connected')
            # Send greeting
            await self.sendMessage('Hey server, this is webSocket client')
            return self.connection


    async def sendMessage(self, message):
        '''
            Sending message to webSocket server
        '''
        await self.connection.send(message)

    async def receiveMessage(self, connection):
        '''
            Receiving all server messages and handling them
        '''
        while True:
            try:
                message = await connection.recv()
                print('Received message from server: ' + str(message))
            except websockets.exceptions.ConnectionClosed:
                print('Connection with server closed')
                break

    async def heartbeat(self, connection):
        '''
        Sending heartbeat to server every 5 seconds
        Ping - pong messages to verify connection is alive
        '''
        while True:
            try:
                await connection.send('ping')
                await asyncio.sleep(5)
            except websockets.exceptions.ConnectionClosed:
                print('Connection with server closed')
                break

主要:

import asyncio
from webSocketClient import WebSocketClient

if __name__ == '__main__':
    # Creating client object
    client = WebSocketClient()
    loop = asyncio.get_event_loop()
    # Start connection and get client connection protocol
    connection = loop.run_until_complete(client.connect())
    # Start listener and heartbeat 
    tasks = [
        asyncio.ensure_future(client.heartbeat(connection)),
        asyncio.ensure_future(client.receiveMessage(connection)),
    ]

    loop.run_until_complete(asyncio.wait(tasks))

现在,客户端保持活动状态监听来自服务器的所有消息,并每隔5秒向服务器发送“ping”消息。