How can I continually send data without shutdown socket connection in python

Question

I wrote a python client to communicate with server side. Each time when I finished sanding out data, I have to call sock.shutdown(socket.SHUT_WR), otherwise the server would not do any response. But after calling sock.shutdown(socket.SHUT_WR), I have to reconnect the connection as sock.connect((HOST, PORT)), other wise I can not send data to server. So how can I keep the connection alive without close it. My sample code as following:

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((HOST, PORT))
sock.sendall(data)
sock.shutdown(socket.SHUT_WR)
received = sock.recv(1024)
while len(received)>0:
    received = sock.recv(1024)
sock.sendall(newdata) # this would throw exception

The Server Side code as following:

def handle(self):
    cur_thread = threading.current_thread()
    while True:
        self.data = self.rfile.read(bufsiz=100)
        if not self.data:
            print 'receive none!'
            break
        try:
            data = self.data
            print 'Received data, length: %d' % len(data)
            self.wfile.write('get received data\n')
        except Exception:
            print 'exception!!'

Irmen de Jong · Accepted Answer · 2016-08-15 17:49:33Z

1

You didn't show any server side code but I suspect it simply reads bytes until it gets none anymore.

You can't do this as you found out, because then the only way to tell the server the message is complete is by killing the connection.

Instead you'll have to add some form of framing in your protocol. Possible approaches include a designated stop character that the server recognises (such as a single newline character, or perhaps a 0-byte), sending frames in fixed sizes that your client and server agree upon, or send the frame size first as a network encoded integer followed by exactly the specified number of bytes. The server then first reads the integer and then exactly that same number of bytes from the socket.

That way you can leave the connection open and send multiple messages.

answered Aug 15, 2016 at 17:49

Irmen de Jong

2,8771 gold badge17 silver badges26 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How can I continually send data without shutdown socket connection in python

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related