Scaling-up a pizza ordering service

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Scaling-up a pizza ordering service#

You are working in a pizza shop to earn some money as a student making pizzas. One day the shop owner says:

The last weeks the order have been decreasing. Maybe we have to reduce your hours. A customer complained that our website is too slow.

You don’t want to reduce your hours.

Maybe I may not be able to pay for my flat in København ☹️

you think desperately.

You have a software engineering background, so you offer your boss to analyze the code for the web server.

  • Do you see any problems with the following code?

  • How would you improve it?

Tip

Use netcat to test it, e.g.,

$ netcat localhost 12345
as
Wrong number of pizzas, please try again
1
Thank you for ordering 1 pizzas!

from socket import create_server, socket

BUFFER_SIZE = 1024
ADDRESS = ("127.0.0.1", 12345)


class Server:
    def __init__(self) -> None:
        try:
            print(f"Starting up at: {ADDRESS}")
            self.server_socket: socket = create_server(ADDRESS)
        except OSError:
            self.server_socket.close()
            print("\nServer stopped.")

    def accept(self) -> socket:
        conn, client_address = self.server_socket.accept()
        print(f"Connected to {client_address}")
        return conn

    def serve(self, conn: socket) -> None:
        """Serve the incoming connection by sending and receiving data."""
        try:
            while True:
                data = conn.recv(BUFFER_SIZE)
                if not data:
                    break
                try:
                    order = int(data.decode())
                    response = f"Thank you for ordering {order} pizzas!\n"
                except ValueError:
                    response = "Wrong number of pizzas, please try again\n"
                print(f"Sending message to {conn.getpeername()}")
                # send a response
                conn.send(response.encode())
        finally:
            print(f"Connection with {conn.getpeername()} has been closed")
            conn.close()

    def start(self) -> None:
        """Start the server by continuously accepting and serving incoming
        connections."""
        print("Server listening for incoming connections")
        try:
            while True:
                conn = self.accept()
                self.serve(conn)
        finally:
            self.server_socket.close()
            print("\nServer stopped.")


if __name__ == "__main__":
    server = Server()
    server.start()

Credits#

Based on:

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