python - How to keep a socket open until client closes it?

Question

I have simple python server and client.

Server:

import SocketServer
import threading


class MyTCPHandler(SocketServer.BaseRequestHandler):
    def handle(self):
        self.data = self.request.recv(1024).strip()
        print str(self.client_address[0]) + " wrote: "
        print self.data
        self.request.send(self.data.upper())


if __name__ == "__main__":
    HOST, PORT = "localhost", 3288
    server = SocketServer.TCPServer((HOST, PORT), MyTCPHandler)
    server.serve_forever()

Client:

import socket
import sys
from time import sleep

HOST, PORT = "localhost", 3288
data = "hello"

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

try:
    sock.connect((HOST, PORT))
    sock.send(data + "
")
    received = sock.recv(1024)

    sleep(10)

    sock.send(data + "
")
    received = sock.recv(1024)

    sleep(10)

    sock.send(data + "
")
    received = sock.recv(1024)

finally:
    sock.close()

Here is the output I get:

Server:

>python server.py
127.0.0.1 wrote:
hello

Client:

>python client.py
Traceback (most recent call last):
  File "client.py", line 18, in <module>
    received = sock.recv(1024)
socket.error: [Errno 10053] An established connection was aborted by the software in your host machine

I tried it on a linux machine as well. The server only receives one message and then I get an error on the recv statement of second message. I have just started learning networking on python but I think the server is closing the socket for some reason. How do I correct this?

Answer 1

A MyTcpHandler object is created for each connection, and handle is called to deal with the client. The connection is closed when handle returns, so you have to handle the complete communication from the client within the handle method:

class MyTCPHandler(SocketServer.BaseRequestHandler):
    def handle(self):
        while 1:
            self.data = self.request.recv(1024)
            if not self.data:
                break
            self.data = self.data.strip()
            print str(self.client_address[0]) + " wrote: "
            print self.data
            self.request.send(self.data.upper())

NOTE: recv returns '' when the client closes the connection, so I moved .strip() after the recv so there is no false alarm due to the client sending only white space.