Python Network Programming

Python delivers two levels of right-to-network services. At a low level, you can access the elementary socket reinforcing in the underlying operating system, which authorizes you to utilize clients and servers for both connection-oriented and connection-less protocols. Python is loaded with wide libraries supplying exact protocols like FTP, HTTP, etc high-level application network programming. This chapter delivers you an understanding of the most illustrious concept in Networking - Socket Programming.

What is Sockets?

Sockets are considered as the last points of a bi-directional statements channel. Sockets might converse within a procedure, between courses on the aforementioned machine, or amid processes on dissimilar continents.

Sockets might be put into practice over several assorted channel kinds: Unix domain sockets, TCP, UDP, etc. The socket library offers exact classes for running the ordinary transports and a general interface for managing the rest.

Do sockets have their own vocabulary?

The socket Module

To make a socket, you must utilize the socket.socket() function easy to get to in socket module, which has the universal syntax:

s = socket.socket (socket_family, socket_type, protocol=0)

Here is the description of the parameters-

• socket_family- This is either AF_UNIX or AF_INET, as explained earlier.
• socket_type- This is either SOCK_STREAM or SOCK_DGRAM.
• protocol- This is usually left out, defaulting to 0.

Once users possess socket objects, in such scenarios, users could use the needed functions to create a client or server program.

Following is the list of functions required-

Server Socket Methods

Client Socket Methods

General Socket Methods

A Simple Server

To write Internet servers, programmers need to utilize the socket function obtainable in the socket module to develop a socket object. A socket object is then utilized to call additional functions to system a socket server.

Now call bind(hostname, port) function to state a port for service on the provided host.

Next, call the accept method of the returned object. This method stays unless a client attaches to the port that users specified, and then returns a connection object that depicts the link to that client.

#!/usr/bin/python           # This is server.py file

import socket               # Import socket module

s = socket.socket()         # Create a socket object
host = socket.gethostname() # Get local machine name
port = 12345                # Reserve a port for your service.
s.bind((host, port))        # Bind to the port

s.listen(5)                 # Now wait for client connection.
while True:
   c, addr = s.accept()     # Establish connection with client.
   print 'Got connection from', addr
   c.send('Thank you for connecting')
   c.close()                # Close the connection

A Simple Client

Let us write a simple client program that unlocks a connection supposing to a provided port 54321 and host. This is simple to expand a socket user using Python's socket module function.

The socket.connect(hosname, port ) unbolts a TCP connection to hostname on the port. Once users possess a socket open, then they could interpret from accepting as IO object. When completed, keep in mind to close it, as users need to close a file.

The following code is a simple client that connects to a provided host and port, reads any available data from the socket, and then exits-

#!/usr/bin/python           # This is client.py file

import socket               # Import socket module

s = socket.socket()         # Create a socket object
host = socket.gethostname() # Get local machine name
port = 12345                # Reserve a port for your service.

s.connect((host, port))
print s.recv(1024)
s.close()                     # Close the socket when done

Now run this server.py in the background and then run above client.py to see the result.

# Following would start a server in background.
$ python server.py & 

# Once server is started run client as follows:
$ python client.py

This would supply the following results:

Got connection from ('127.0.0.1', 48437)
Thank you for connecting

Python Internet modules

A list of some important modules in Python Network/Internet programming.

Please check all the libraries mentioned above to work with FTP, SMTP, POP, and IMAP protocols.

Here at Intellinuts, we have created a complete Python tutorial for Beginners to get started in Python.