How can I read byte array coming from server in UWP app? - tcp

Question

I have a client-server app. The client is HoloLens 2 and the server is unity running on PC. I have created a socket using HoloLens but I can't read the byte array on HoloLens. In the connect method _inputStream and _outputStream are System.IO.Streams.
PC client uses System.Net.Sockets.TcpClient, System.Net.Sockets.NetworkStream but UWP (HoloLens) uses Windows.Networking.Sockets.StreamSocket.
In the ReceiveCallback I have an issue with int byteLenght = _inputStream.EndRead(result); When I tried this code on HoloLens I got the exception: "System.ArgumentException: The specified AsyncResult does not correspond to any outstanding IO operation". But I tested it with PC client (System.Net.Socket) and everything works fine.
Btw, I gave all related permissions.
How can I read byte array in UWP app?
Update:
#if UNITY_EDITOR
private void ConnectUWP(string host, string port)
#else
private async void ConnectUWP(string host, string port)
#endif
{
#if UNITY_EDITOR
errorStatus = "UWP TCP client used in Unity!";
#else
try
{
socket = new Windows.Networking.Sockets.StreamSocket();
Windows.Networking.HostName serverHost = new Windows.Networking.HostName(host);
_receivedData = new Packet();
_receiveBuffer = new byte[DataBufferSize];
await socket.ConnectAsync(serverHost, port);
successStatus = "Connected!";
_outputStream = socket.OutputStream.AsStreamForWrite();
//_streamWriter = new StreamWriter(_outputStream) { AutoFlush = true };
_inputStream = socket.InputStream.AsStreamForRead();
Task.Run(() => StreamToBytes(socket.InputStream));
}
catch (Exception e)
{
errorStatus = e.ToString();
Debugger.GetComponent<TextMeshPro>().text += "\n Exception: " + errorStatus;
}
#endif
#if !UNITY_EDITOR
public async Task StreamToBytes(Windows.Storage.Streams.IInputStream stream)
{
using (var reader1 = new Windows.Storage.Streams.DataReader(stream))
{
reader1.InputStreamOptions = Windows.Storage.Streams.InputStreamOptions.ReadAhead;
reader1.UnicodeEncoding = Windows.Storage.Streams.UnicodeEncoding.Utf8;
reader1.ByteOrder = Windows.Storage.Streams.ByteOrder.LittleEndian;
//InBuffer is always 256,
//even if there is more data waiting. If I put a task.delay in it will always return 25
try
{
await reader1.LoadAsync(256);
}
catch (Exception ex)
{
//..
}
while (reader1.UnconsumedBufferLength > 0)
{
var bytes1 = new byte[reader1.UnconsumedBufferLength];
reader1.ReadBytes(bytes1);
_receivedData.Reset(await HandleData(bytes1));
await reader1.LoadAsync(256);
}
reader1.DetachStream();
}
}
private async Task<bool> HandleData(byte[] data)
{
int packetLength = 0;
_receivedData.SetBytes(data);
if (_receivedData.UnreadLength() >= 4)
{
// If client's received data contains a packet
packetLength = _receivedData.ReadInt();
if (packetLength <= 0)
{
// If packet contains no data
return true; // Reset receivedData instance to allow it to be reused
}
}
while (packetLength > 0 && packetLength <= _receivedData.UnreadLength())
{
// While packet contains data AND packet data length doesn't exceed the length of the packet we're reading
byte[] packetBytes = _receivedData.ReadBytes(packetLength);
ThreadManager.ExecuteOnMainThread(() =>
{
using (Packet packet = new Packet(packetBytes))
{
int packetId = packet.ReadInt();
_packetHandlers[packetId](packet); // Call appropriate method to handle the packet
}
});
packetLength = 0; // Reset packet length
if (_receivedData.UnreadLength() >= 4)
{
// If client's received data contains another packet
packetLength = _receivedData.ReadInt();
if (packetLength <= 0)
{
// If packet contains no data
return true; // Reset receivedData instance to allow it to be reused
}
}
}
if (packetLength <= 1)
{
return true; // Reset receivedData instance to allow it to be reused
}
return false;
}
#endif

Answer 1

When I tried this code on HoloLens I got the exception: "System.ArgumentException: The specified AsyncResult does not correspond to any outstanding IO operation".
Please refer to BeginRead method document, In the .NET Framework 4 and earlier versions, you have to use methods such as BeginRead and EndRead to implement asynchronous I/O operations. These methods are still available in the .NET Framework 4.5 to support legacy code; however, the new async methods, such as ReadAsync, WriteAsync, CopyToAsync, and FlushAsync, help you implement asynchronous I/O operations more easily. I suppose this old api could not compatible with HoloLens device, so please try to use ReadAsync to replace like the following
byte[] bytes = await StreamToBytes(_inputStream);
public async Task<byte[]> StreamToBytes(Stream stream)
{
byte[] bytes = new byte[stream.Length];
await stream.ReadAsync(bytes, 0, bytes.Length);
stream.Seek(0, SeekOrigin.Begin);
return bytes;
}
Or follow the official's processing that use DataReader to read ReadBytes, for more code please refer streamsocket.
Update
using (var reader1 = new DataReader(_inputStream)
{
reader1.InputStreamOptions = Windows.Storage.Streams.InputStreamOptions.Partial;
reader1.UnicodeEncoding = Windows.Storage.Streams.UnicodeEncoding.Utf8;
reader1.ByteOrder = Windows.Storage.Streams.ByteOrder.LittleEndian;
await reader1.LoadAsync(256); //InBuffer is always 256,
//even if there is more data waiting. If I put a task.delay in it will always return 25
while (reader1.UnconsumedBufferLength > 0)
{
var bytes1 = new byte[reader1.UnconsumedBufferLength];
reader1.ReadBytes(bytes1);
await reader1.LoadAsync(256);
}
reader1.DetachStream();
}

Answer 2

I tried everything for TCP but TCP is nearly impossible for HoloLens with UWP app. So I tried UDP and it works perfectly (https://github.com/mbaytas/HoloLensUDP). I hope Microsoft put a TCP example for HoloLens 1 and 2 in near future. Thanks Nico for your help.