server.py

from twisted.application import internet, service
from twisted.internet.protocol import ServerFactory, Protocol 
from twisted.protocols import amp
from twisted.python import log
import optparse

# Normally we would import these classes from another module.
class ChangePrice(amp.Command):
     arguments = [('newPrice', amp.Integer())]

class Protocol(Protocol):
    def connectionMade(self):
        self.factory.connections.append(self)
    
    def changePrice(self, price):
        self.factory.service.price = self.factory.service.price + price
        self.factory.sendPrice()

class Factory(ServerFactory):

    protocol = Protocol

    def __init__(self, service):
        self.service = b4buy_service
        self.connections = [] 

    def sendPrice(self):
        for connection in self.factory.connections:
            connection.callRemote(ChangePrice, newPrice=price) 



class Service(service.Service):

    def __init__(self): # the in-game parameters will be here
        self.products = 0 

    def startService(self):
        service.Service.startService(self)
        

# configuration parameters
port = 45000 
iface = '0.0.0.0' 

# this will hold the services that combine to form the server
top_service = service.MultiService()

# the service holds the parameters. it will load the poem when it is
# started
b4buy_service = Service()
b4buy_service.setServiceParent(top_service)

# the tcp service connects the factory to a listening socket. it will
# create the listening socket when it is started
factory = Factory(service)
tcp_service = internet.TCPServer(port, factory, interface=iface)
tcp_service.setServiceParent(top_service)

# this variable has to be named 'application'
application = service.Application("client")

# this hooks the collection we made to the application
top_service.setServiceParent(application)

# at this point, the application is ready to go. when started by
# twistd it will start the child services, thus starting up the
# server