Question

Well I’m making a Client-Server application and I can send messages to my client just fine but when I do it the other way around (Client to server) the server application just closes down, any help on how to fix this?

public void OnDataReceived(IAsyncResult asyn)
    {
        try
        {
            SocketPacket socketData = (SocketPacket)asyn.AsyncState;

            int iRx = 0;
            iRx = socketData.m_currentSocket.EndReceive(asyn);
            char[] chars = new char[iRx + 1];
            System.Text.Decoder d = System.Text.Encoding.UTF8.GetDecoder();
            int charLen = d.GetChars(socketData.dataBuffer,
                                     0, iRx, chars, 0);
            System.String szData = new System.String(chars);
            area1.AppendText(szData);


            WaitForData(socketData.m_currentSocket); // Continue the waiting for data on the Socket
        }
        catch (ObjectDisposedException)
        {
            System.Diagnostics.Debugger.Log(0, "1", "\nOnDataReceived: Socket has been closed\n");
        }
        catch (SocketException se)
        {
            MessageBox.Show(se.Message);
        }
    }

After doing some breakpoints I realized it closes after reaching this part when it tries to append it on the textArea it closes without an error.

Any ideas on how to fix this? I guessing something to do with the threads but not sure why it just closes.

Answer 1

Does an exception happen when AppendText is called? If yes, can you include the call stack? Is szData valid data when AppendText is called? Try putting a try/catch around the code to get the exception information:

try
{
    ... your code...
}
catch (Exception e)
{
    ... examine 'e' in the debugger or dump it to a log file
}

One thing that might be going wrong is that you are accessing a UI control from the non-UI thread, but it could be other things. It’s hard to tell from the code snippet you posted.

Updated:
If the exception was that the control is being invoked from the wrong thread, you can try adding a function like this, then calling that instead of accessing the control directly (untested):

    private void AppendText(string text)
    {
        // InvokeRequired required compares the thread ID of the
        // calling thread to the thread ID of the creating thread.
        // If these threads are different, it returns true.
        if (this.area1.InvokeRequired)
        {   
            SetTextCallback d = new AppendTextCallback(AppendText);
            this.Invoke(d, new object[] { text });
        }
        else
        {
            this.area1.AppendText(text);
        }
    }