Sending data via TCP

Sending data over the internet is made possible using multiple modules. The sockets module provides low-level access to the underlying Operating System operations responsible for sending or receiving data from other computers or processes.

The following code sends the byte string b'Hello' to a TCP server listening on port 6667 on the host localhost and closes the connection when finished:

from socket import socket, AF_INET, SOCK_STREAM
s = socket(AF_INET, SOCK_STREAM)
s.connect(('localhost', 6667))  # The address of the TCP server listening
s.send(b'Hello')
s.close()

Socket output is blocking by default, that means that the program will wait in the connect and send calls until the action is ‘completed’. For connect that means the server actually accepting the connection. For send it only means that the operating system has enough buffer space to queue the data to be send later.

Sockets should always be closed after use.