driverRPCServer.send(ControlMessage.ClientToDriverMessage.newBuilder() .setType(ControlMessage.ClientToDriverMessageType.LaunchDAG) .setLaunchDAG(ControlMessage.LaunchDAGMessage.newBuilder() .setDag(serializedDAG) .setBroadcastVars(ByteString.copyFrom(SerializationUtils.serialize((Serializable) broadcastVariables)))