Flutter websocket closes after some time - flutter

Question

const CIM_HOST = "";
const CIM_PORT = '34567';
const CIM_URI = "wss://" + CIM_HOST;
_channel = WebSocketChannel.connect(
Uri.parse(CIM_URI),
);
_channel.sink.add(protobuff);
_channel.stream.listen(
//on message
(event) {
var list = event;
var bytes = Uint8List.fromList(list);
var type = bytes[0];
var body = bytes.sublist(1, bytes.length);
final message = js.context.callMethod('type2deserializeBinary', [body]);
print(message.toString());
if (message == null) {
_channel.sink.close();
timer.cancel();
// Navigator.pushReplacement<void, void>(
// context,
// MaterialPageRoute<void>(
// builder: (BuildContext context) => LoginScreen(),
// ),
// );
} else {
List<String> result = message.toString().split(',');
if (currentid == result[3]) {
int id = int.parse(result[3]);
setMessage("reply", result[2], id, 'text');
// print(result);
}
}
},
//on close
onDone: () {
debugPrint('ws channel closed');
//reconnect to socket server
},
//on error
onError: (error) {
debugPrint('ws error $error');
},
);`enter code here`
i have this code to connect to the socket and to list the messages but the connection gets closed after some time.i tried to call the connection method again inside the ondone but that causes the list values to duplicate so can anyone tell me how to maintain the connection.