/tcp-client-serv

Primary LanguagePython

tcp-client-serv

Client-Server Socket Library (TCP)

Library written in Python 3.7, for easy client-server communication through sockets (TCP)

Prerequisites

server.py & client.py must be in the same folder of your .py file.

To import all classes from server.py:

from server import *

To import all classes from client.py:

from client import *

Getting Started

server.py

There are 3 kinds (classes) of server included in library (server.py):

Server
IterativeServer
MultithreadedServer

To create a server object (i.e. simple Server):

server = Server(port, protocol)

or

server = Server(protocol=MyServerProtocol()) # port is by default 1234

Same logic for the other two classes (IterativeServer, MultithreadedServer).

listen()python function establishes connection with client:

server.listen() # server is ready to receive request

client.py

To create an object of Client class:

client = Client(host, port, protocol)

or

my_port = 2345
client = Client(port=my_port, protocol=MyClientProtocol()) # host is by default localhost

or

client = Client(protocol=MyClientProtocol()) # host is by default localhost, 
                                             # port is by default 1234

open() function establishes connection with Server (server must probably be listening):

client.open() # client tries to connect with server
              # when connected, sends the request
              # receives reply
              # and closes connection

Server

Server will wait for a request, will send response (if no errors will occure) and will close the connection. Server will be used for one and only request.

Usage Example
server = Server(protocol=a_server_protocol())  # create server object (must create a protocol to pass)

server.listen() # server will listen for one request only

IterativeServer

IterativeServer will serve one client at a time, until it is stopped (CTRL + C).

Usage Example
server = IterativeServer(protocol=a_server_protocol())  # create server object (must create a protocol to pass)

server.listen() # server will listen forever, and serve one client each time (not 2 or more parallel)

MultithreadedServer

Multithreaded server creates a thread, for each request arrives. The difference here (comparing to IterativeServer) is that our server can serve multiple requests in parallel. Server is active until it is stopped (CTRL + C).

Usage Example
server = MultithreadedServer(protocol=a_server_protocol())  # create server object (must create a protocol to pass)

server.listen() # server will listen forever, and serve multiple client requests in parallel

Instructions

Server

  1. Create a class (i.e. MyServerProtocol) & implement ServerProtocol abstract class.

  2. Implement process_request() function (PyCharm screenshot):

alt text

  1. Server knows what to do on request through process_request() function. input_msg is client's request.
class MyServerProtocol(ServerProtocol):

  def process_request(self, input_msg):

          output = 'Hello Client!' # prints hello to client, when a request arrives

          return output
  1. After finishing your protocol, it is time to integrate it in our server:
if __name__ == '__main__':  # server_main.py

    server_protocol = MyServerProtocol() # create protocol we written
    
    server = MultiThreadedServer(protocol=server_protocol) # pass it to server (i.e. MultithreadedServer)
    
    server.listen() # server now listening for requests from clients

Client

  1. Create a class (i.e. MyClientProtocol) & implement ClientProtocol abstract class.

  2. Implement prepare_request & process_reply function (PyCharm screenshot):

alt text

  1. Client knows what kind of request to send through prepare_request() function, process_reply() function is for printing server's message. input_msg (process_reply() parameter) is server's reply.
class MyClientProtocol(ClientProtocol):

    def prepare_request(self):

        output = 'Hello Server!'

        return output

    def process_reply(self, input_msg):
        print('Response: ', input_msg)
  1. After finishing writing your protocol, it is time to integrate it in our client object:
if __name__ == '__main__':  # client_main.py

    client_protocol = MyClientProtocol() # create protocol we written
    
    client = Client(protocol=client_protocol) # pass it to client
    
    client.open() # client will now try to establish connection with server. 
                  # If it does, client will send the request to server
                  # When a reply comes back, connection closes

Credits

Legacy code: Professor K.G. Margaritis