使用Twisted框架实现客户端和服务器之间的数据传输

使用 Twisted 框架来实现客户端和服务器之间的数据传输非常简单。Twisted 是一个异步事件驱动的框架，常用于构建网络应用程序。下面是一个简单的示例，展示了如何使用 Twisted 来实现客户端和服务器之间的基本数据传输。

1、问题背景

在这个问题中，我们需要创建一个客户端和服务器，客户端向服务器发送请求，而服务器需要将请求转发到另一个文件服务器，然后从文件服务器获取响应并将其返回给客户端。其中，客户端和服务器之间的通信使用 Twisted 框架的 WebSocket 协议，而服务器和文件服务器之间的通信也使用 WebSocket 协议。

2、解决方案

为了解决这个问题，我们需要编写三个程序，分别是客户端程序、服务器程序和文件服务器程序。

客户端程序

import os
import time
from random import shuffle
from twisted.internet import reactor
from autobahn.websocket import WebSocketClientFactory, WebSocketClientProtocol, connectWS

class DFSClientProtocol(WebSocketClientProtocol):

    def onOpen(self):
        text_files = [f for f in os.listdir(".\\initial") if f.endswith('.txt')]

        # write data into DFS
        shuffle(text_files)
        for file_name in text_files:
            file_path = str(".\\initial\\"+file_name)
            f = open(file_path, 'r')
            message = '[W]['+file_name+']'+f.read()
            self.sendMessage(message)
            f.close()

        # read from DFS
        shuffle(text_files)
        for file_name in text_files:
           message = '[R]['+file_name+']'
           self.sendMessage(message)

    def onMessage(self, msg, binary):
        typeMsg = msg[:3]
        file_name = msg[4:16]
        if typeMsg == '[C]':
            message = msg[17:]
            file_path = str(".\\read\\"+file_name)
            f = open(file_path, 'w')
            f.write(message)
            f.close()

if __name__ == '__main__':
    factory = WebSocketClientFactory("ws://" + ADDRESS + ":" + str(PORT), debug = False)
    factory.protocol = DFSClientProtocol
    connectWS(factory)
    print 'connecting to %s port %s' % (ADDRESS, PORT)
    reactor.run()

服务器程序

import time
from socket import gethostbyaddr
from twisted.internet import reactor
from autobahn.websocket import WebSocketServerFactory, WebSocketServerProtocol, listenWS, WebSocketClientFactory, WebSocketClientProtocol, connectWS

class FSClient(WebSocketClientProtocol):

    def onOpen(self):
        # send request to Fileserver
        self.sendMessage(OPERATION)

    def onMessage(self, msg, binary):
        # get response from Fileserver and resend to Server
        self.sendMessage(msg)


class DFS(WebSocketServerProtocol):

    def onOpen(self):
        peer = self.transport.getPeer()
        print "[USER][%s] User with %s connected" % (time.strftime("%H:%M:%S"), peer)

    def connectionLost(self, reason):
        print '[USER][%s] Lost connection from %s' % (time.strftime("%H:%M:%S"), self.transport.getPeer())

    def onMessage(self, msg, binary):
        typeMsg = msg[:3]
        file_name = msg[4:16]
        if typeMsg == '[W]':
            print "[W][%s] Write %s file into DFS" % (time.strftime("%H:%M:%S"), file_name)
            # at this place i want to send request to FSClient and this object send request for Fileserver
            # Client -> Server -> FSClient -> Fileserver
            # and when fileserver doing somework, he send response by sheme:
            # Fileserver -> FSclient -> Server -> Client 
        elif typeMsg == '[R]':
            print "[R][%s] Read %s file from DFS" % (time.strftime("%H:%M:%S"), file_name)

if __name__ == '__main__':
    import sys
    if len(sys.argv)<2:
        sys.exit("Using server.py [SERVERS]")
    factory = WebSocketServerFactory("ws://" + ADDRESS + ":" + str(PORT), debug = False)
    SERVERS = int(sys.argv[1])
    factory.protocol = DFS
    listenWS(factory)
    print 'Server starting up on %s port %s' % (ADDRESS, PORT)
    reactor.run()

文件服务器程序

import time
from socket import gethostbyaddr
from twisted.internet import reactor
from autobahn.websocket import WebSocketServerFactory, WebSocketServerProtocol, listenWS

class FS(WebSocketServerProtocol):

    def onOpen(self):
        peer = self.transport.getPeer()
        print "[USER][%s] User with %s connected" % (time.strftime("%H:%M:%S"), peer)

    def connectionLost(self, reason):
        print '[USER][%s] Lost connection from %s' % (time.strftime("%H:%M:%S"), self.transport.getPeer())

    def onMessage(self, msg, binary):
        typeMsg = msg[:3]
        file_name = msg[4:16]
        if typeMsg == '[W]':
            print "[W][%s] Write %s file into %s" % (time.strftime("%H:%M:%S"), file_name, CATALOG_NAME)
            message = msg[17:]
            file_path = FILES_PATH + file_name
            f = open(file_path, 'w')
            f.write(message)
            f.close()
            print "File %s successfully writen..." % file_name
            self.sendMessage('[C]['+file_name+']OK')
        elif typeMsg == '[R]':
            print "[R][%s] Read %s file from %s" % (time.strftime("%H:%M:%S"), file_name, CATALOG_NAME)
            print "File %s successfully read..." % file_name
            file_path = FILES_PATH + file_name
            f = open(file_path, 'r')
            message = '[O]['+file_name+']' + f.read()
            f.close()
            self.sendMessage(message)

if __name__ == '__main__':
    import sys
    if len(sys.argv)<4:
        sys.exit("Using fileserver.py [IP] [PORT] [file_catalog_name]")
    ADDRESS = str(sys.argv[1])
    PORT = int(sys.argv[2])
    CATALOG_NAME = str(sys.argv[3])
    FILES_PATH = '.\\data\\' + CATALOG_NAME + '\\'
    factory = WebSocketServerFactory("ws://" + ADDRESS + ":" + str(PORT), debug = False)
    factory.protocol = FS
    listenWS(factory)
    print 'Server starting up on %s port %s' % (ADDRESS, PORT)
    reactor.run()

通过运行这三个程序，即可实现客户端和服务器之间的通信，以及服务器和文件服务器之间的通信。其中，文件服务器存储了需要访问的文件，而服务器则负责接收客户端的请求并转发到文件服务器，最后将文件服务器的响应返回给客户端。
在这个程序中，WebSocket 协议不仅用于客户端和服务器之间的通信，还用于服务器和文件服务器之间的通信。WebSocket 协议是一个双向的协议，允许客户端和服务器在建立单一 TCP 连接的情况下进行双向通信。在 Twisted 框架中，WebSocketServerFactory 和 WebSocketClientFactory 分别用于创建 WebSocket 服务器和 WebSocket 客户端，而 WebSocketServerProtocol 和 WebSocketClientProtocol 分别用于实现 WebSocket 服务器和 WebSocket 客户端的协议处理逻辑。

通过这个示例，你可以轻松地使用 Twisted 实现客户端与服务器之间的数据传输，并根据需求调整逻辑。