Overview Of Python Socketserver.TCPServer With Example

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Overview:

A TCP Server program can be created using the classes

  • TCPServer
  • StreamRequestHandler

from the socketserver module of Python Standard Library.

The steps involved in creating a TCP Server and request handling are given here with an example. The client part of TCP client-server program written with POSIX API is used to connect to the example TCP Server program.

Server Creation:

  • TCP based server programs can be created using the socket.TCPServer class.

 

  • The TCPServer class is a class derived from the socketserver.BaseServer which provides a  generic interface for network servers.

 

  • Once a TCPServer instance is created, it can be supplied with a
    • A tuple containing the IP address and Port Number
    • Request handler to handle incoming requests from the client

 

  • To handle requests for a TCP server the socketserver provided StreamRequestHandler could be used.

 

  • StreamRequestHandler class is a specialized, sub-class of BaseRequestHandler.

 

  • StreamRequestHandler acts as a base request handler for TCP based servers, which provide connection oriented, streaming and reliable communication over the network.

 

  • To start the TCP server method serve_forever() needs to be called on the TCPServer instance.

Handling Requests from Clients:

  • Though StreamRequestHandler forms the base for TCP based request handlers – it further delegates the implementation of  handle()method to the sub-classes.

 

  • In the sample program below class MyTCPRequestHandler is derived from StreamRequestHandler.

 

  • MyTCPRequestHandler overrides the handle() method and this forms the core of handling data sent from the client connections.

 

  • StreamRequestHandler derived instances has got two attributes that help in the data exchange between the client and server.

 

  • The attribute wfile is used to write any content that needs to be sent to the client.

 

  • The attribute rfile is used to write any content that needs to be received from the client.

 

Example:

# import the socketserver module of Python

import socketserver

 

# Create a Request Handler

# In this TCP server case - the request handler is derived from StreamRequestHandler

class MyTCPRequestHandler(socketserver.StreamRequestHandler):

 

# handle() method will be called once per connection

    def handle(self):

        # Receive and print the data received from client

        print("Recieved one request from {}".format(self.client_address[0]))

        msg = self.rfile.readline().strip()

        print("Data Recieved from client is:".format(msg))

        print(msg)  

       

        # Send some data to client

        self.wfile.write("Hello Client....Got your message".encode())

            

# Create a TCP Server instance

aServer         = socketserver.TCPServer(("127.0.0.1", 9090), MyTCPRequestHandler)

 

# Listen for ever

aServer.serve_forever()

                             

 

Output – Server Side:

Recieved one request from 127.0.0.1

Data Recieved from client is:

b'GET / HTTP/1.1'

 

Output – Client Side:

Connected to localhost

b'Hello Client....Got your message'

b''

Connection closed

 

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