QtWebSocket sending binary data with msgpack to ESP32 mcu

Kris Revi

Setup

Qt Running

QtWebSockets/QWebSocket
msgpack ported by (https://github.com/romixlab/qmsgpack)

ESP32 Running

WebSocketsServer
msgpack ported by (https://github.com/hideakitai/MsgPack)

Outputs

Qt

[SOCKET][BINARY][ "colorPicker" ] QVariant(int, 0)
Binary Data :  "\x81\xAB""colorPicker\x00"
Binary Length :  14

ESP32

[HEXDUMP] Address: 0x3FFD4D9C len: 0xE (14)
[0x3FFD4D9C] 0x00000000: 81 AB 63 6F 6C 6F 72 50 69 63 6B 65 72 00 
Binary : ��colorPicker
Payload Length : 14

everything is correct except it wont give me the 0 in colorPicker 0 it just says colorPicker if i send it a 1 or 2 or 3 or any other number i get colorPicker 1 and it works but for some reason 0 just escapes :S

SGaist

Hi,

How are you showing that data ? I may be wrong but I think you are hitting the usual termination character handling issue. QByteArray is binary data but if you handle its content as string it will be cut at the termination char.

Kris Revi

@SGaist

void MainWindow::on_comboBoxSelectStrip_activated(int index)
{
    qDebug() << "[SelectedStrip][Currently] : " << index;
    sendBinary("selectedstrip", index);
}

void MainWindow::sendBinary(QString text, QVariant args)
{
    _MsgPackMap.clear();
    _MsgPackMap.insert(text, args);
    _MsgPackArray = MsgPack::pack(_MsgPackMap);
    _socket.sendBinaryToStrip(_MsgPackArray);
}

void Socket::sendBinaryToStrip(const QByteArray data)
{
    m_webSocket.sendBinaryMessage(data);
    qDebug() << "Binary Data : " << data;
    qDebug() << "Binary Length : " << data.size();
}

Christian Ehrlicher

So how long is the binary length with 0 and with 1?
Also what is _MsgPackMap?

Kris Revi

@Christian-Ehrlicher

to quote the website of msgpack It's like JSON. but fast and small.

the variable itself is QVariantMap _MsgPackMap;

let me check the length and get back to you!

Edit

selectedStrip = 0

[SelectedStrip][Currently] :  0
Binary Data :  "\x81\xADselectedstrip\x00"
Binary Length :  16

selectedStrip = 1

[SelectedStrip][Currently] :  1
Binary Data :  "\x81\xADselectedstrip\x01"
Binary Length :  16

Christian Ehrlicher

Looks like a problem on the receiver side:

int main(int argc, char **argv)
{
  QCoreApplication app(argc, argv);
  QVariantMap  v0, v1;
  v0.insert("selectedstrip", 0);
  v1.insert("selectedstrip", 1);
  qDebug() <<  MsgPack::pack(v0);
  qDebug() <<  MsgPack::pack(v1);
  return 0;
}

-->
"\x81\xADselectedstrip\x00"
"\x81\xADselectedstrip\x01"

Kris Revi

@Christian-Ehrlicher

so on the ESP32 side i printed out msgpack unpacked data and the payload from arduinowebsocket and NONE of them prints out anything when "selectedStrip = 0"

            if ( mIndata["selectedstrip"] )
            {
                Serial.print("selectedstrip : ");
                Serial.print((int)mIndata["selectedstrip"]);
                Serial.println(" ");
                Serial.print("Payload : ");
                for ( int i = 0; i < length; i++ )
                    Serial.print(payload[i]);
                Serial.println(" ");

                _selectedStrip = mIndata["selectedstrip"];
            }

selectedstrip : 1
Payload : 129173115101108101991161011001151161141051121 
selectedstrip : 2
Payload : 129173115101108101991161011001151161141051122 
selectedstrip : 3
Payload : 129173115101108101991161011001151161141051123 
selectedstrip : 4
Payload : 129173115101108101991161011001151161141051124

so i would guess the problem is the arduinowebsocket? or am i wrong?

Christian Ehrlicher

@Kris-Revi said in QtWebSocket sending binary data with msgpack to ESP32 mcu:

is the arduinowebsocket?

Looks like - QWebSocket::sendBinaryMessage() works correct I would guess.

Kris Revi

@Christian-Ehrlicher as @SGaist said

@SGaist said in QtWebSocket sending binary data with msgpack to ESP32 mcu:

QByteArray is binary data but if you handle its content as string it will be cut at the termination char.

on the ESP32 side i do this

MsgPack::Unpacker unpacker;
MsgPack::map_t<String, int> mIndata;

Kris Revi

@Christian-Ehrlicher so i printed the payload inside if ( mIndata["selectedstrip"] ) { } moved it outside of that and got a result on "selectedStrip = 0"

1

selectedstrip : 1 
Payload : 1291731141011136810111810599101731101021111

0

Payload : 129173115101108101991161011001151161141051120

notice that msgpack does not print on 0 only payload

Christian Ehrlicher

I don't really know how binary data is encoded in websocket (if at all) but what you can do is to create a simple receiver with Qt websocket to see if it properly arrives there and can be decoded.

SGaist

@Kris-Revi said in QtWebSocket sending binary data with msgpack to ESP32 mcu:

if ( mIndata["selectedstrip"] )

You know that this if is going to fail if the the value associated with selectedstrip equals 0 ?

Kris Revi

@SGaist OH SHIT! i never thought of that xD