class MongoMessageHandler {
 final _log = new Logger('MongoMessageTransformer');
 final converter = new PacketConverter();
//  final debugData = new File('debug_data1.bin').openSync(mode: FileMode.WRITE);
void handleData(List<int> data, EventSink<MongoReplyMessage> sink) {
 //    debugData.writeFromSync(data);
 //    debugData.flushSync();
 //_log.fine('handleData length=${data.length} $data');
   converter.addPacket(data);
   while (!converter.messages.isEmpty) {
     var buffer = new BsonBinary.from(converter.messages.removeFirst());
     MongoReplyMessage reply = new MongoReplyMessage();
     reply.deserialize(buffer);
     _log.fine(reply.toString());
     sink.add(reply);
   }
 }
 void handleDone(EventSink<MongoReplyMessage> sink) {
   if (!converter.isClear) {
     _log.warning('Invalid state of PacketConverter in handleDone: $converter');
   }
   sink.close();
 }
 StreamTransformer<List<int>, MongoReplyMessage> get transformer => new StreamTransformer<List<int>, MongoReplyMessage>.fromHandlers(
     handleData: handleData,handleDone: handleDone);
}