Public Class Form1
    Inherits System.Windows.Forms.Form
 
#Region " Vom Windows Form Designer generierter Code "
 
    Private PlugIn As MyInterface.PlugIn
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        ' alle PlugIns müssen in den anwendungsordner -> unterordner PlugIns
        Dim PlugIns() As String = System.IO.Directory.GetFiles( _
          Application.StartupPath & "\PlugIns")
        If PlugIns.Length = 0 Then
            ' kein PlugIn gefunden
        Else
            ' mindestens ein PlugIn gefunden
            ' ich berücksichtige hier auch nur eines!!
            Dim f1 As IO.FileStream = New IO.FileStream(PlugIns(0), _
              IO.FileMode.Open)
            Dim rawAssemblyBytes1(f1.Length) As Byte
            f1.Read(rawAssemblyBytes1, 0, CType(f1.Length, Integer))
            f1.Close()
            Dim a As System.Reflection.Assembly = AppDomain.CurrentDomain.Load( _
              rawAssemblyBytes1)
 
            PlugIn = a.CreateInstance(a.EntryPoint.ReflectedType.Namespace & _
              ".PlugInClass")
        End If
    End Sub
#End Region
 
    Private Sub cmdladen_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles cmdladen.Click
        PlugIn.Load()
    End Sub
 
    Private Sub cmdzeigen_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles cmdzeigen.Click
        PlugIn.Show()
    End Sub
 
    Private Sub cmdschließen_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles cmdschließen.Click
        PlugIn.Close()
    End Sub
End Class

Public Class PlugInClass
    Implements MyInterface.PlugIn
 
    Private frm As frmMain
    Public Function Close() As Boolean Implements MyInterface.PlugIn.Close
        Try
            frm.Close()
            frm.Dispose()
            frm = Nothing
            Return True
        Catch ex As Exception
            Return False
        End Try
    End Function
 
    Public Function Load() As Boolean Implements MyInterface.PlugIn.Load
        Try
            frm = New frmMain
            Return True
        Catch ex As Exception
            Return False
        End Try
 
    End Function
 
    Public Function Show() As Boolean Implements MyInterface.PlugIn.Show
        Try
            frm.ShowDialog()
            Return True
        Catch ex As Exception
            Return False
        End Try
    End Function
End Class