Question

I’m using python socket server to which I connect with Android and periodically send messages.
I have a problem that the request is closed on every sent message and i need it to remain opened until Android decides to close it.

Curentlly it looks like this:

class SingleTCPHandler(SocketServer.StreamRequestHandler):
    def handle(self):
    try:
        while True:
            message = self.rfile.readline().strip()  # clip input at 1Kb            
            my_event = pygame.event.Event(USEREVENT, {'control':message})
            pygame.event.post(my_event)
    except KeyboardInterrupt:
        sys.exit(0)
    finally:
        self.request.close()

I’ve solved this by adding a while True in my handle() definition, however, this was criticized as a bad solution and that the right way to go is to override the process_request and shutdown methods.

Attempt of solution

I removed the while from the code, connected to the server locally with netcat, sent a message and went to see when will the connection be closed.

I wanted to see what is the method after which the connection is being closed to figuer out what i have to override.

I have stepped with the debugger through the serve_forever() and followed it to this part of code:

> /usr/lib/python2.7/threading.py(495)start()
    494         try:
--> 495             _start_new_thread(self.__bootstrap, ())
    496         except Exception:

After line 495 is passed (i can’t step into it) the connection is closed.

I somehow doubt that it’s such a hustle to maintain a connection via socket, that is basically the reason why we chosen to communicate over a socket, to have a continuous connection and not a ‘one connection per sent message’ system.

Ideas on implementation, or links?

Answer 1

The handle method is called for each client connection, and the connection is closed when it returns. Using a while loop is fine. Exit the loop when the client closes the connection.

Example (Python 3 syntax):

class EchoHandler(socketserver.StreamRequestHandler):

    def setup(self):
        print('{}:{} connected'.format(*self.client_address))

    def handle(self):
        while True:
            data = self.request.recv(1024)
            if not data: break
            self.request.sendall(data)

    def finish(self):
        print('{}:{} disconnected'.format(*self.client_address))