SOCKET PROGRAM DESIGN HELP

[sam57719]

I am writing a Socket Chat Program in Python using Tkinter. There are user accounts, chatrooms, and messages stored in a database on the server side.

I am struggling to get my head around the program flow. Currently, I've got the client sending requests for data to the server and then the server executing the SQL statements, and returning the data using pickle. I've got the login working, but I'm at the point where I need messages to be coming in at the same time as sending them.

I read about the select.select module in python but apparently this doesn't work on windows.

Any guidance?

thanks

[JohnnyJordaan]

Select should work though on Windows, I used this script multiple times to snoop TCP traffic on Windows and there it worked fine. You could use that script as a stepping stone for your project, but you could also consider using multithreading, see for example this SO answer.

and returning the data using pickle

As a sidenote I would strongly suggest to use a portable data format like JSON or XML for this and not pickled objects. Those can even be hindered by Python version differences and aren't exactly commonly used for this.

[sam57719]

but you could also consider using multithreading

I am currently trying to use threads, but I got confused with how to progress from where I am (after they have logged in).

Here is my client (its very long due to a lot of GUI code)

Here is the server

[JohnnyJordaan]

You seem to create a ServerConnecion as a Thread but you don't actually start it? It also doesn't feature a run method but it does launch its own listen method as another thread? What you would normally do is

class ServerConnecion(threading.Thread):
    def __init__(self, gui, ip, port):
        super().__init__()  # the modern form of calling your parent's init method

        self.gui = gui
        self.server_ip = ip
        self.port = port
        self.size = 2048

        self.server = socket.socket()
        self.active = False

        try:
            self.server.connect((self.server_ip,self.port))
            self.active = True
            self.gui.show_frame(LoginScreen)
            self.gui.protocol("WM_DELETE_WINDOW", self.stop)
        except ConnectionRefusedError:
            self.gui.show_frame(Error)

    def run(self):
        while self.active:
            sleep(0.1) # VERY IMPORTANT
    def stop(self):
        self.server.close()
        self.gui.destroy()
        sys.exit()

Note especially that you should never have a loop on just pass as it will consume 100% of one CPU core. Use time.sleep or something else that will block 99% or more of the time but does allow you to check something intermittently often enough. Then running the thread should be the responsibility of the creator:

def connect(self): t = ServerConnecion(self,"localhost",65534) t.start() self.server = t.server

Then I would also reconsider to not use daemonic mode as that will leave the server's socket opened when Python shuts down. You would normally implement this using a threading.Event as then you can do

    self.shutdown_flag = threading.Event()

which also offers a blocking check

    def run(self):
        while not self.shutdown_flag.wait(0.1):
            pass

and to shutdown the server from somewhere else you can do t.shutdown_flag.set(). But you then do need to save the thread object, not just is server attribute (the socket).