[Twisted-Python] Create client in Server factory
Phil Mayers
p.mayers at imperial.ac.uk
Wed Oct 31 03:49:33 MDT 2012
On 10/31/2012 07:14 AM, Grégoire Leroy wrote:
> Hi,
>
> I have a server who receive data from clients A/B/C (remote machines). I want
> to use a client D (on the same machine than the server) to send this data to
> another server (remote).
>
> The difficulty is, I want to use the same client D connection for any client. I
> don't want open an new connection each time.
>
> First thing I would think is to create the connection in my server factory,
> and use client's methods in my server protocol, for example with
> [...]
> class LocalProxyFactory(Factory):
> def __init__(self):
> f = LocalProxyClientFactory()
> reactor.connectTCP("retenodus.net", 4242, f)
> reactor.run()
The "reactor.run" is just wrong - remove it.
You need to connect to a server, and share this connection amongst some
protocols. But you can't control the order in which these connections
complete, so A/B/C might connect before D is ready.
You've really got two choices - accept the connections from A/B/C but
have your server protocol "wait" until D is ready - something like this:
from twisted.internet.protocol import ClientCreator
class Server(...):
def connectionMade(self):
if self.factory.connD is None:
self.factory.waitFor(self._ready)
self.transport.pauseProducing()
def _ready(self):
self.transport.resumeProducing()
d_connect = ClientCreator(reactor, DProtocol)
class ServerFactory(...):
def __init__(self):
self.connD = None
self._wait = []
d_connect.connectTCP(Dhost, port).addCallback(self.dReady)
def waitFor(self, _cb):
if self.connD:
_cb(self.connD)
else:
d = defer.Deferred()
d.addCallback(_cb)
self._wait.append(d)
def dReady(self, proto):
self.connD = proto
cb = self._wait
self._wait = []
for c in cb:
c.callback(proto)
def main():
reactor.listenTCP(..., ServerFactory())
reactor.run()
...or don't start listening until D has connected, like this:
class ServerFactory(...):
def __init__(self, dProto):
self.connD = dProto
def startListen(dProto):
reactor.listenTCP(..., ServerFactory(dProto))
def main():
d_connect.connectTCP(Dhost, port).addCallback(startListen)
reactor.run()
The latter is simpler, but which is appropriate depends on your needs.
Note that I've used ClientCreator to get a callback when the connection
to D is ready - remember that doesn't happen immediately.
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