Im trying to write a basic server / client application in python, where the clients sends the numbers 1-15 to the server, and the server prints it on the server side console.

Code for client:

import socket
clientsocket.connect(('localhost', 8303))
def updateX():x = 0while (x < 15):xclientsocket.send(format(x))print xx = x+1updateX()

server:

import socketHOST = 'localhost'
PORT = 8303
s= socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind((HOST, PORT))
s.listen(5) # become a server socket, maximum 5 connections
connection, address = s.accept()while True:connection, address = s.accept()buf = connection.recv(64)print buf

The output of running the client while the server is live results in either no output, prints only 1, or prints only 12. Ideas?

Before entering the main loop on the server side, you accept a connection:

connection, address = s.accept()

But then in the loop itself you begin by accepting a connection:

while True:connection, address = s.accept()buf = connection.recv(64)print buf

As a result, you never read from the first connection. That's why you don't see any output.

Note also that it's wrong (for what you're trying to do) to accept a new connection on every iteration. Even if you keep making new client connections, the server will accept a connection on each iteration and read from the socket once, but then continue the next iteration and wait for a new connection, never reading more data sent by a client. You should be making multiple recv calls on the same connection object instead.

You might find this tutorial helpful.