Question

I am looking for a way to periodically send some data over all clients connected to a TCP port. I am looking at twisted python and I am aware of reactor.callLater. But how do I use it to send some data to all connected clients periodically ? The data sending logic is in Protocol class and it is instantiated by the reactor as needed. I don’t know how to tie it from reactor to all protocol instances…

Answer 1

You would probably want to do this in the Factory for the connections. The Factory is not automatically notified of every time a connection is made and lost, so you can notify it from the Protocol.

Here is a complete example of how to use twisted.internet.task.LoopingCall in conjunction with a customised basic Factory and Protocol to announce that ’10 seconds has passed’ to every connection every 10 seconds.

from twisted.internet import reactor, protocol, task  class MyProtocol(protocol.Protocol):     def connectionMade(self):         self.factory.clientConnectionMade(self)     def connectionLost(self, reason):         self.factory.clientConnectionLost(self)  class MyFactory(protocol.Factory):     protocol = MyProtocol     def __init__(self):         self.clients = []         self.lc = task.LoopingCall(self.announce)         self.lc.start(10)      def announce(self):         for client in self.clients:             client.transport.write('10 seconds has passed\n')      def clientConnectionMade(self, client):         self.clients.append(client)      def clientConnectionLost(self, client):         self.clients.remove(client)  myfactory = MyFactory() reactor.listenTCP(9000, myfactory) reactor.run()