[Twisted-Python] AMP with a long-lived connection - results and deferred?

[Oon-Ee Ng]

And lo and behold it seems to work now even with Kivy. Strange. For
posterity, here's the simple client code I was using for a minimal
example. I'll expand upwards from here and see how far I can get.

#install_twisted_rector must be called before importing the reactor
from kivy.support import install_twisted_reactor
install_twisted_reactor()

from twisted.internet import reactor, protocol
from twisted.internet.task import deferLater
from ampserver import Sum, Divide
from twisted.protocols import amp

class EchoClient(amp.AMP):
    def connectionMade(self):
        self.factory.resetDelay()
        self.factory.app.on_connection(self)


class EchoFactory(protocol.ReconnectingClientFactory):
    protocol = EchoClient

    def __init__(self, app):
        self.app = app


from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.textinput import TextInput
from kivy.uix.boxlayout import BoxLayout


# A simple kivy App, with a textbox to enter messages, and
# a large label to display all the messages received from
# the server
class TwistedClientApp(App):
    connection = None

    def build(self):
        root = self.setup_gui()
        self.connect_to_server()
        return root

    def setup_gui(self):
        self.textbox = TextInput(size_hint_y=.1, multiline=False)
        self.textbox.bind(on_text_validate=self.send_message)
        self.label = Label(text='connecting...\n')
        self.layout = BoxLayout(orientation='vertical')
        self.layout.add_widget(self.label)
        self.layout.add_widget(self.textbox)
        return self.layout

    def connect_to_server(self):
        reactor.connectTCP('127.0.0.1', 1234, EchoFactory(self))

    def on_connection(self, connection):
        self.print_message("connected succesfully!")
        self.connection = connection

    def send_message(self, *args):
        msg = self.textbox.text.encode('ascii')
        if self.connection:
            d = self.connection.boxReceiver.callRemote(Sum, a=3, b=8)
            def prin(result):
                print(result)
            d.addCallback(prin)

    def print_message(self, msg):
        self.label.text += str(msg) + "\n"

if __name__ == '__main__':
    TwistedClientApp().run()