How connect my Kivy client to a server (TCP, Sockets) - python-3.x

Question

So as part of my project (2D Multiplayer Card Game), I've figured out how to host and run a server script online. My plan is to have two separate kivy clients connect to the server (which will just be a script with commands).
However I'm somewhat confused about the order of operations because I think the client connection is potentially in conflict with the message loop so I'm wondering if someone could basically tell me what I should be doing:
I'm going to be using this as my serverscript:
import socket
serversocket = socket.socket()
host = 'INSERTIPHERE'
port = PORTHERE
serversocket.bind(('', port))
serversocket.listen(1)
while True:
clientsocket,addr = serversocket.accept()
print("got a connection from %s" % str(addr))
msg = 'Thank you for connecting' + "\r\n"
clientsocket.send(msg.encode('ascii'))
clientsocket.close()
This is my client connection function
def Main():
host = 'INSERTIPHERE'
port = PORTHERE
mySocket = socket.socket()
mySocket.connect((host, port))
message = input(' -> ')
while message != 'q':
mySocket.send(message.encode())
data = mySocket.recv(1024).decode()
print('Received from server: ' + data)
message = input(' -> ')
mySocket.close()
Note: I understand that the server and client aren't perfectly aligned in functions but provided I can at least a connection confirmation for now, I can work from there.
I'm basically wondering how do I put this code into a simple kivy app like this:
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
class BoxWidget(BoxLayout):
pass
class BoxApp(App):
def build(self):
return BoxWidget()
if __name__ == '__main__':
BoxApp().run()
My best guess is that you want to:
Establish the connection before opening the client
Passing the server connection to the primary widget (in this case the Box Widget) as you're running an instance of the client (ie BoxApp(server).run()?)
Use that connection in a message loop function of the BoxWidget
I also understand that Kivy has built in solutions with Twisted but I'm having trouble with the python 2-3 differences.
Thank you for reading.
Just to clarify: All I want to do right now is open a blank window and also have a confirmation message sent to the command line (or failing that a label in the window).

Answer 1

You can use threading so you don't interrupt the main thread in kivy.
I rewrote your example a bit, so what you send from the server, will be the text of a label.
server.py
import socket
serversocket = socket.socket()
host = 'localhost'
port = 54545
serversocket.bind(('', port))
serversocket.listen(1)
clientsocket,addr = serversocket.accept()
print("got a connection from %s" % str(addr))
while True:
msg = input("> ") + "\r\n"
clientsocket.send(msg.encode('ascii'))
client.py
import socket
class MySocket:
def __init__(self,host="localhost",port=54545):
self.sock = socket.socket()
self.sock.connect((host, port))
def get_data(self):
return self.sock.recv(1024)
main.py
from kivy.app import App
from kivy.uix.label import Label
from client import *
from threading import Thread
class MyLabel(Label):
def __init__(self, **kwargs):
super(MyLabel,self).__init__(**kwargs)
self.sock = MySocket()
Thread(target=self.get_data).start()
def get_data(self):
while True:
self.text = self.sock.get_data()
class BoxApp(App):
def build(self):
return MyLabel()
if __name__ == '__main__':
BoxApp().run()
Now just run server.py in one terminal, then main.py from another

Answer 2

I got a basic version of it working with buttons. Both on local machine and online. This Solution is likely not viable for many real time apps or even a chat server since the reply has to be initiated. However for my goal of a multiplayer card game it should more than suffice with proper conditionals.
video of test on local machine
EDIT: In the video I talk about double clicking. I have just realized this is because the first click is putting the window back in focus.
EDIT 2: Using TextInput in kv file instead of input in Python file.
server script:
import socket
def Main():
host = '127.0.0.1'
port = 7000
mySocket = socket.socket()
mySocket.bind((host,port))
mySocket.listen(1)
conn, addr = mySocket.accept()
print ("Connection from: " + str(addr))
message = 'Thank you connecting'
conn.send(message.encode())
while True:
data = conn.recv(1024).decode()
strdata = str(data)
print(strdata)
reply = 'confirmed'
conn.send(reply.encode())
mySocket.close()
if __name__ == '__main__':
Main()
This is a pretty simple server. Listen for a single client, confirm connection, open a send and receive message loop.
This is the client script which isn't hugely complicated really:
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ObjectProperty
import socket
class BoxWidget(BoxLayout):
s = socket.socket()
host = '127.0.0.1'
port = 7000
display = ObjectProperty()
def connect_to_server(self):
# called by a Button press
# Connects to the server
self.s.connect((self.host, self.port))
# Receives confirmation from Server
data = self.s.recv(1024).decode()
# Converts confirmation to string
strdata = str(data)
# Prints confirmation
print(strdata)
def send_message(self):
# Is called by the function below
# Encodes and sends the message variable
self.s.send(self.message.encode())
# Waits for a reply
self.receive_message()
def message_to_send(self):
# Defines Message to send
self.message = self.display.text
# Calls function to send the message
self.send_message()
# Note
# When I used message = input directly in send_message,
# the app would crash. So I defined message input
# in its own function which then calls the
# send function
# message_to_send is the function actually
# called by a button press which then
# starts the chain of events
# Define Message, Send Message, get Reply
def receive_message(self):
# Decodes a reply
reply = self.s.recv(1024).decode()
# Converts reply to a str
strreply = str(reply)
# prints reply
print(strreply)
class ServerApp(App):
def build(self):
box = BoxWidget()
return box
if __name__ == '__main__':
ServerApp().run()
Edit: Forgot to include the kv file
<BoxWidget>:
display: display
Button:
text: 'Hello'
on_press: root.message_to_send()
Button:
text: 'Connect'
on_press: root.connect_to_server()
TextInput:
id: display
In future iterations, I'll be replacing print statements with conditionals (ie did client one draw a card? if so client 2's opponent draws a face-down card etc).
Relatively rudimentary as it is now but there is a lot you could do from here.