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Problems to receive messages from server on HoloLens

Hi guys,

I am developing an app which needs to connect to server in order to receive messages. I am using TCP/IP protocol because I need to establish a previous connection. Becuase of the problem with the System.Net.Sockets library I am using Windows.Networking.Socket library.
The code to use the aforementioned protocol is as follows:

using System;
using System.IO;
using HoloToolkit.Unity;
using UnityEngine;
#if !UNITY_EDITOR
using System.IO;
using System.Threading.Tasks;
using Windows.Networking;
using Windows.Networking.Sockets;
#endif

/// <summary>
/// TcpNetworkClientManager class provides methods to
/// send and receive messages asynchronously
/// </summary>
public class TcpNetworkClientManager : Singleton<TcpNetworkClientManager>
{
    #region PRIVATE_MEMBERS_VARIABLES
    [SerializeField]
    [Tooltip("The Ipv4 address of the machine to connect")]
    private string ip = "127.0.0.1";

    [SerializeField]
    [Tooltip("The connection port on the machine to use")]
    private int port = 9999;

    /// <summary>
    /// The message we receive
    /// </summary>
    private string message;

    /// <summary>
    /// Tracks if a client is connected
    /// </summary>
    private bool clientConnected;

    /// <summary>
    /// Flag to receive message
    /// </summary>
    private bool receiveFlag;

#if !UNITY_EDITOR
    /// <summary>
    /// Supports network communication
    /// </summary>
    StreamSocket socket;

    /// <summary>
    /// Stream of data to write
    /// </summary>
    private StreamWriter writer = null;

    /// <summary>
    /// Stream of data to read
    /// </summary>
    private StreamReader reader = null;
#endif
    #endregion // PRIVATE_MEMBERS_VARIABLES

    #region PUBLIC_MEMBERS_VARIABLES
    public string Ip
    {
        get
        {
            return ip;
        }
        set
        {
            ip = value;
        }
    }

    public int Port
    {
        get
        {
            return port;
        }
        set
        {
            port = value;
        }
    }

    public string Message
    {
        get
        {
            return message;
        }
        set
        {
            message = value;
        }
    }

    public bool ClientConnected
    {
        get
        {
            return clientConnected;
        }
    }
    #endregion // PUBLIC_METHODS

    #region MONOBEHAVIOUR_METHODS
    protected override void Awake()
    {
        base.Awake();
        Message = string.Empty;
        clientConnected = false;
    }
    #endregion // MONOBEHAVIOUR_METHODS

    #region PUBLIC_METHODS
    /// <summary>
    /// Connects to a tcp server using TCP/IP protocol
    /// </summary>
    public void Connect()
    {
        receiveFlag = true;
#if !UNITY_EDITOR
        Task.Run(async () => {
            try
            {
                socket = new StreamSocket();
                await socket.ConnectAsync(new HostName(Ip), Port.ToString());
                clientConnected = true;
                writer = new StreamWriter(socket.OutputStream.AsStreamForWrite());
                reader = new StreamReader(socket.InputStream.AsStreamForRead());
                await Receive();
            }
            catch(Exception)
            {
                Debug.Log("Unable to connecto to server");
            }
        });
#endif
        Debug.LogWarningFormat("Tcp connect not supported in editor");
    }

    /// <summary>
    /// Sends asynchronously a message using TCP/IP protocol
    /// </summary>
    /// <param name="data"></param>
    public void Send(string messageToSend)
    {
#if !UNITY_EDITOR
        if (writer != null) Task.Run(async () =>
        {
            try
            {
                await writer.WriteAsync(messageToSend);
                await writer.FlushAsync();
                Debug.Log("Sent: " + messageToSend);
            }
            catch(Exception)
            {
                Debug.Log("Unable to send message to server");
            }
        });
#endif
        Debug.LogWarningFormat("Tcp send not supported in editor");
    }

    /// <summary>
    /// Frees resources both reader and writer
    /// </summary>
    public void Close()
    {
#if !UNITY_EDITOR
        receiveFlag = false;

        if (writer != null) writer.Dispose();
        writer = null;

        if (reader != null) reader.Dispose();
        reader = null;
#endif
        Debug.LogWarningFormat("Tcp close not supported in editor");
    }
    #endregion // PUBLIC_METHODS

    #region PRIVATE_METHODS
    /// <summary>
    /// Receives asynchronously a message using TCP/IP protocol
    /// </summary>
#if !UNITY_EDITOR
    private async Task Receive()
    {
        if (reader != null)
        {
            while (receiveFlag)
            {
                try
                {
                    if (clientConnected)
                    {
                        string messageToReceive = await reader.ReadToEndAsync();
                        if (messageToReceive != null)
                        {
                            Message = messageToReceive;
                            Debug.Log("Received: " + message);
                        }
                    }
                }
                catch (Exception)
                {
                    Debug.Log("Unable to receive from server");
                }
            }
        }
    }
#endif
    #endregion // PRIVATE_METHODS
}

Although I can connect to the server, I do not receive anything. I know that the Receive() function reaches to

string messageToReceive = await reader.ReadToEndAsync();

but the next statements are not called, that is, the thread is waiting for data, but the data never is received.

Does anyone know what trouble I am having?

Thanks in advance,
Cristian.

Best Answer

  • Answer ✓

    I found the solution after trying different approaches. The code that solved the problem is as follows:

    char[] buffer = new char[bufferSize];
    int bytes = await reader.ReadAsync(buffer, 0, buffer.Length);
    
        if (bytes > 0)
        {
            string result = new string(buffer, 0, bytes);
            message = result;
    
            Debug.Log("Received: " + message);
        }
    

    The problem was ReadToEndAsync, since with a stream socket there should be no "end of stream" delimiter.

    I hope this approach can help someone,
    Cristian.

Answers

  • Answer ✓

    I found the solution after trying different approaches. The code that solved the problem is as follows:

    char[] buffer = new char[bufferSize];
    int bytes = await reader.ReadAsync(buffer, 0, buffer.Length);
    
        if (bytes > 0)
        {
            string result = new string(buffer, 0, bytes);
            message = result;
    
            Debug.Log("Received: " + message);
        }
    

    The problem was ReadToEndAsync, since with a stream socket there should be no "end of stream" delimiter.

    I hope this approach can help someone,
    Cristian.

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