Const READ_BUFFER_SIZE As Integer = 255
    Const PORT_NUM As Integer = 10000
 
    Private client As TcpClient
    Private readBuffer(READ_BUFFER_SIZE) As Byte
 
    ' Pop up a Connect user dialog and send a message requesting user to log in 
    ' to chat.
    Sub AttemptLogin()
        Dim frmConnectUser As New frmConnectUser
        frmConnectUser.StartPosition = FormStartPosition.CenterParent
        frmConnectUser.ShowDialog(Me)
        SendData("CONNECT|" & frmConnectUser.txtUserLogin.Text)
        frmConnectUser.Dispose()
    End Sub
 
    ' This is the callback function for TcpClient.GetStream.Begin to get an
    ' asynchronous read.
    Private Sub DoRead(ByVal ar As IAsyncResult)
        Dim BytesRead As Integer
        Dim strMessage As String
 
        Try
            ' Finish asynchronous read into readBuffer and return number of 
            ' bytes read.
            BytesRead = client.GetStream.EndRead(ar)
            If BytesRead < 1 Then
                ' If no bytes were read server has close.  Disable input window.
                MarkAsDisconnected()
                Exit Sub
            End If
 
            ' Convert the byte array the message was saved into, minus two for 
            ' the
            ' Chr(13) and Chr(10)
            strMessage = Encoding.ASCII.GetString(readBuffer, 0, BytesRead - 2)
 
            'ruft die funktion auf die das fenster erstellt (im orginal 
            ' programm filter die
            'funktion noch die einzelnen nachrichten typen (z.b. chat, login, 
            ' disconnect usw)
            ProcessCommands(strMessage)
 
            ' Start a new asynchronous read into readBuffer.
            client.GetStream.BeginRead(readBuffer, 0, READ_BUFFER_SIZE, _
              AddressOf DoRead, Nothing)
        Catch e As Exception
            MarkAsDisconnected()
        End Try
    End Sub
 
    ' Send the server a disconnect message  
    Private Sub frmMain_Closing(ByVal sender As Object, ByVal e As _
      System.ComponentModel.CancelEventArgs) Handles MyBase.Closing
        ' Send only if server is still running.
        If cbe_status.SelectedIndex <> 0 Then
            SendData("DISCONNECT")
        End If
    End Sub
 
    ' When the form starts, this subroutine will connect to the server and 
    ' attempt to
    ' log in.
    Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Dim frmConnectUser As New frmConnectUser
 
        Try
            ' The TcpClient is a subclass of Socket, providing higher level 
            ' functionality like streaming.
            client = New TcpClient("localhost", PORT_NUM)
 
            ' Start an asynchronous read invoking DoRead to avoid lagging the 
            ' user
            ' interface.
            client.GetStream.BeginRead(readBuffer, 0, READ_BUFFER_SIZE, _
              AddressOf DoRead, Nothing)
 
            ' Make sure the window is showing before popping up connection 
            ' dialog.
            Me.Show()
 
            AttemptLogin()
        Catch Ex As Exception
            MsgBox("Server is not active.  Please start server and try again.", _
                   MsgBoxStyle.Exclamation, Me.Text)
            Me.Dispose()
        End Try
 
    End Sub
 
    Private Sub ProcessCommands(ByVal strMessage As String)
        'hier wird das fenster geöffnet das sich aufhängt 
        dim test as frm_fenster
         test = new frm_fenster
         test.show
    End Sub