Hey everyone... Firstly let me tell you this is a project that is probably alittle over my head... I have played with programming most of my life, but I have only been doing VB 2005 for about 2 weeks. I know the concepts of most issues, but multi-threading seems to be giving me a headache... anyways here is what is happening...
I have use the MSDN code sample to create a Async TCP server (using sockets, and beginaccept, etc, not Tcplistener or TcpClient), and converted it some to work in a windows form. I got that working, sending all information to a Msgbox as it is transfered from the Console application for the client, no bugs were in this part of the code as far as I know. But on attempting to change Textbox1 in Form1, I realized that I couldn't (it was in the original thread, whereas the message was in the async tcp thread). I have spent a few days trying to learn to use the invoke statement. Seems it is working, as the textbox does get changed to reflect my stream that I recieve from the client. BUT and there is always a BUT I guess, I now get this error at the last End Sub of my async server code.
Getting System.InvalidO perationExcepti on was unhandled
The Undo operation encountered a context that is different from what was applied in the corresponding Set operation. The possible cause is that a context was Set on the thread and not reverted(undone ).
this is the code I added to the server code to invoke the textbox1 in form1.
and the code from the Form1.vb
at then end of my async class:
when I comment out
I will no longer get the error, but the textbox (of course) does not update. And as I mentioned, the textbox does get updated right before I see the error message pup up, with a break in my code the error message shows at the End Sub 'SendCallback
To some this code may look femiliar as I used an example that was posted on these forms.
Thanks in advance, and if you need more information feel free to ask, this is just a pet project for me, but something I would really like to fix, my whole project seems to depend on it.
I have use the MSDN code sample to create a Async TCP server (using sockets, and beginaccept, etc, not Tcplistener or TcpClient), and converted it some to work in a windows form. I got that working, sending all information to a Msgbox as it is transfered from the Console application for the client, no bugs were in this part of the code as far as I know. But on attempting to change Textbox1 in Form1, I realized that I couldn't (it was in the original thread, whereas the message was in the async tcp thread). I have spent a few days trying to learn to use the invoke statement. Seems it is working, as the textbox does get changed to reflect my stream that I recieve from the client. BUT and there is always a BUT I guess, I now get this error at the last End Sub of my async server code.
Getting System.InvalidO perationExcepti on was unhandled
The Undo operation encountered a context that is different from what was applied in the corresponding Set operation. The possible cause is that a context was Set on the thread and not reverted(undone ).
this is the code I added to the server code to invoke the textbox1 in form1.
Code:
Public Class AsynchronousSocketListener
' Thread signal.
Public Shared allDone As New ManualResetEvent(False)
Delegate Sub UpdateTextBox(ByVal message As String)
Private Shared Sub Handler1(ByVal strInMessage As String)
Dim f As Form1 = My.Application.OpenForms("Form1")
f.Invoke(New UpdateTextBox( _
AddressOf f.UpdateMessage), New Object() {strInMessage})
End Sub
Code:
Public Sub UpdateMessage(ByVal strInMessage As String)
Me.TextBox1.Text = strInMessage & vbCrLf & Me.TextBox1.Text
End Sub
Code:
Private Shared Sub SendCallback(ByVal ar As IAsyncResult)
' Retrieve the socket from the state object.
Dim handler As Socket = CType(ar.AsyncState, Socket)
' Complete sending the data to the remote device.
Dim bytesSent As Integer = handler.EndSend(ar)
Handler1("Sent " & bytesSent & " bytes to client." & vbCrLf & Form1.TextBox1.Text)
handler.Shutdown(SocketShutdown.Both)
handler.Close()
' Signal the main thread to continue.
allDone.Set()
'Form1.TextBox1.Text = "Sent " & bytesSent & " bytes to client." & vbCrLf & Form1.TextBox1.Text
End Sub 'SendCallback
Code:
Handler1("Sent " & bytesSent & " bytes to client." & vbCrLf & Form1.TextBox1.Text)
To some this code may look femiliar as I used an example that was posted on these forms.
Thanks in advance, and if you need more information feel free to ask, this is just a pet project for me, but something I would really like to fix, my whole project seems to depend on it.
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