# Read username, output from non-empty factory, drop connections # Use deferreds, to minimize synchronicity assumptions # Write application. Save in 'finger.tpy' from twisted.application import service, strports from twisted.internet import protocol, reactor, defer from twisted.protocols import basic class FingerProtocol(basic.LineReceiver): def lineReceived(self, user): d = self.factory.getUser(user) def onError(err): return 'Internal error in server' d.addErrback(onError) def writeResponse(message): self.transport.write(message + b'\r\n') self.transport.loseConnection() d.addCallback(writeResponse) class FingerFactory(protocol.ServerFactory): protocol = FingerProtocol def __init__(self, users): self.users = users def getUser(self, user): return defer.succeed(self.users.get(user, b"No such user")) application = service.Application('finger', uid=1, gid=1) factory = FingerFactory({b'moshez': b'Happy and well'}) strports.service("tcp:79", factory, reactor=reactor).setServiceParent( service.IServiceCollection(application))