class DialInClient(object):
    def __init__(self, host, port, timeout=100000000, user='root', password='lablab'):
        self._host = host
        self._port = port
        self._timeout = float(timeout)
        self._channel = None
        self._cisco_ems_stub = None
        self._connected = False
        self._metadata = [('username', user), ('password', password)]

    def subscribe(self, sub_id):
        sub_args = CreateSubsArgs(ReqId=1, encode=3, subidstr=sub_id)
        stream = self._cisco_ems_stub.CreateSubs(sub_args, timeout=self._timeout, metadata=self._metadata)
        for segment in stream:
            yield segment

    def connect(self):
        self._channel = grpc.insecure_channel(':'.join([self._host,self._port]))
        try:
            grpc.channel_ready_future(self._channel).result(timeout=10)
            self._connected = True
        except grpc.FutureTimeoutError as e:
            raise DeviceFailedToConnect from e
        else:
            self._cisco_ems_stub = gRPCConfigOperStub(self._channel)