[2005][resolved] New Thread interact with Form

[qazwsx]

Is there anyway for a new thread to interact with my original form. For example

Sub createhoneypots()
        Dim honeylisten As New System.Threading.Thread(AddressOf Module1.honeylisten)

        honeypot = New System.Net.Sockets.TcpListener(System.Net.IPAddress.Any, 2999)
        honeylisten.Start()
    End Sub

    Sub honeylisten()
        MsgBox("")
        Try
            honeypot.Start()
            MsgBox("")
            Form1.txthresults.Text = Form1.txthresults.Text & "Honeypot Succesfully Created on port: 2999" & vbNewLine
            honeypot.AcceptTcpClient()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub

That code does not write the message to the txtbox but it does show all the message boxes so i know it is getting to that code.

[Fromethius]

Search for jmcilhinney and invokerequired

[qazwsx]

Ok i looked at those posts, thank you they were very helpful and i think i am getting closer. This is what i ahve so far:

Sub createhoneypots()
        Dim honeylisten As New System.Threading.Thread(AddressOf Module1.honeylisten)
 
        honeypot = New System.Net.Sockets.TcpListener(System.Net.IPAddress.Any, 2999)
        ' Form1.txthresults.Text = Form1.txthresults.Text & "Honeypot Succesfully Created on port: 2999" & vbNewLine
        honeylisten.Start()
    End Sub
 
    Sub honeylisten()
        MsgBox("")
        Try
            honeypot.Start()
            txtresults("tdf")
            While 1
                If honeypot.Pending() = True Then
                    honeypot.AcceptTcpClient()
                    MsgBox(honeypot.Server.ToString())
                    Exit While
                End If
            End While
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Sub
 
    Private Delegate Sub txtdelegate(ByVal s As String)
 
 
    Sub txtresults(ByVal s As String)
        MsgBox("")
        If Form1.txthresults.InvokeRequired Then
            Form1.txthresults.Invoke(New txtdelegate(AddressOf txtresults), s)
        Else
            Form1.txthresults.Text = s
        End If
    End Sub

However this does nothing but show the message boxes. Could the problem be that all of this code is on a module?

[jmcilhinney]

Follow the last link in my signature for an explanation and examples.

Display a message box directly from a worker thread is not a good idea because it creates a form modal to that thread, which means the main thread can simply ignore it. Any interaction with the UI, including displaying messages, should be performed via delegation.

You might also want to look into using a BackgroundWorker instead of explicitly creating a Thread. There's a link in my signature to a BGW example too.

[qazwsx]

That made things a little clearer; however, I still cannot get it to work with the thread. I removed the Msgboxes. I am jsut wondering, why are background workers preferable?

[jmcilhinney]

BackgroundWorkers are not preferable; they are just easier in many situations. You can use the ReportProgress method and the ProgressChanged and RunWorkerCompleted events to interact with the UI without having to invoke any delegates. All that is handled by the BGW for you. In situations where there is a lot of interaction with the UI a BGW may end up making things more complex though, so they are not always suitable.

[qazwsx]

Hmm i cant seem to figure out why it is not working with the thread. I think my code is almost identical to the examples.

[jmcilhinney]

I'd first like to point out that "txtresults" is a terrible name for a method. I stringly suggest that you immediately change that to something that actually describes its purpose.

As to your issue, in that method you're referring to your TextBox like this:

Form1.txthresults

Do you have a variable in your module named "Form1" that refers to the form you want to access? I''l wager not. In that case you're referring to the default instance of the Form1 class, which is likely to not be the same instance that you've displayed.

You first need to have a variable in your module that refers to the actual Form1 object you want to access. Then you would do something like this:

Private Sub SetResultsText(ByVal results As String)
    If myForm1.InvokeRequired Then
        myForm1.Invoke(New SetResultsTextCallback(AddressOf SetResultsText), results)
    Else
        myForm1.txtResults.Text = results
    End If
End Sub

I recommend against making your controls accessible outside their parent form too.