Python網路編程（一）

標籤：程式   nec   occurs   平台   receive   _id   接受   not   forever   

代碼：

 1 # socket test with ForkingMixIn class 2  3 import os 4 import socket 5 import SocketServer 6 import threading 7 # from multiprocessing import Process 8  9 SERVER_HOST = "localhost"10 SERVER_PORT = 0 # indicat to use dyminic port11 BUF_SIZE = 102412 ECHO_MSG = "Hello echo server"13 14 15 class ForkingClient():16     """a client to use forking server """17     def __init__(self, ip, port):18         self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)19         self.sock.connect((ip, port))20     21     def run(self):22         """ client send infor to server """23         # get current client‘s ip 24         current_process_id = os.getpid()25         print "PID %s sending echo messages to server: %s" % 26             (current_process_id, ECHO_MSG)27         # use sock.send() to get length28         sent_data_length = self.sock.send(ECHO_MSG)29         print "%s characters sent so far..." % sent_data_length30 31         # get the server response32         s_response = self.sock.recv(BUF_SIZE)33         # disp the server response, split s_response34         print "PID %s received: %s" % ( current_process_id, s_response[5:] )35 36     def clientshutdown(self):37         self.sock.close()38 39 # def server‘s handle mthd40 class ForkingServerRequestHandler(SocketServer.BaseRequestHandler):41     def handle(self):42         # get echo from client, notice "request.recv()"43         data = self.request.recv(BUF_SIZE)44         current_process_id = os.getpid()45         s_response = ‘%s: %s‘ % ( current_process_id,  data)46         # send echo back to client47         print "Server sending back [current_process_id: data] %s" % 48             s_response49         # use .request.send() mthd50         self.request.send(s_response)51         # use return52         return53 54 class ForkingServer(SocketServer.ForkingMixIn, SocketServer.TCPServer):55     """ just inherit everything from parents """56     pass57 58 def main():59     # build the server like TCPServer initiate 60     server = ForkingServer( (SERVER_HOST, SERVER_PORT), ForkingServerRequestHandler)61 62     ip, port = server.server_address # get server‘s ip and port63     # serve_forever Handle requests until an explicit shutdown() request. 64     server_thread = threading.Thread(target=server.serve_forever)65     server_thread.setDaemon(True)66 67     # server start68     server_thread.start()69     #server_thread.join()70     print "Server loop runing PID: %s" % os.getpid()71 72     # build client and start73 74     client1 = ForkingClient(ip, port) # use server‘s ip and port75     client1.run()76 77     client2 = ForkingClient(ip, port)78     client2.run()79 80     # clean81     server.shutdown()82     client1.clientshutdown()83     client2.clientshutdown()84     server.socket.close()85 86 if __name__ == ‘__main__‘:87     main()

程式注意點如下：

     1. 初次在Windows上運行時報錯如下， 在協助文檔查詢到os.fork只能運行在unix平台：
　　　　報錯：

　　　　 File "C:\Python27\lib\SocketServer.py", line 556, in process_request

    pid = os.fork()    AttributeError: ‘module‘ object has no attribute ‘fork‘

          os.fork()說明：  

Fork a child process. Return 0 in the child and the child’s process id in the parent. If an error occurs OSError is raised.

Note that some platforms including FreeBSD <= 6.3, Cygwin and OS/2 EMX have known issues when using fork() from a thread.

Availability: Unix.

 

2. 在main塊執行完SERVER和CLIENT的發送及接受後，SERVER執行了shutdown()後又執行socket.close()，為什麼要這麼做？

   shutdown()關閉讀寫的串連並發送Fin/EOF 訊號給所有的節點，而不管有多少進程串連在SERVER上，但是它不釋放串連，所以再調用close()來釋放

 

 

Python網路編程（一）