On Migrating a VB Project to VB.NET

Introduction

There will be certainly a need to migrate applications developed with VB6 to VB.NET. Although simple programs can be migrated without any rework as the present note shows, projects with any complexity may need rework and research. This may lead to the conclusion that it may be easier to start from scratch. The following features in VB projects are not supported in the VB.NET environment:

• OLE Container Control
• Dynamic Data Exchange (DDE)
• DAO or RDO Data Binding
• Visual Basic 5.0 Controls
• DHTML Applications
• ActiveX Documents
• Property Pages

Migration Wizard Dialog

Visual Studio IDE has a menu item to bring up a wizard needed for migrating either VB or Java programs to .NET World. This can be accessed as shown. There also exists a way to convert VB code to VB.NET code which directly works with the code portion of the application. This helps to bring VB code to VB.NET, a small portion at a time instead of the whole project as in this note.

Clicking on Convert brings up the wizard as shown:

You can choose to convert either a VB or a Java application to be migrated to VB.NET. This is followed by the wizard explaining how this conversion will take place:

At this point, you will need to choose the project, *.vbp that you need to migrate, the Browse button may be used to bring in the project to the migration process. In this example, a very simple project called RevStr.vbp is being migrated.

The wizard can handle *.exe as well as *.dll type of projects. In the present case, it is a simple *.exe project.

In the next dialog, you need to select a location where your files can be located for the newly created VB.NET project. If you take the default, it will be created in a subdirectory of the project you are migrating, as in this case. Since it is creating a new directory, it will bring up a dialog to let you know that since the directory does not exist, it will create one as in the following screen:

This is all the information necessary for the upgrade. On clicking 'Next', the upgrade is made while you are watching the progress bar fill up.

Project Explorer and Solution Explorer

Whereas VB's Project Explorer had two forms with their code, the VB.NET migrated project has all the necessary class file references as shown here.

VB Project	After Migration

Code Changes to Files

Original Code for one of the forms:

Function MyReverse(ByVal S As String, ByVal Size As Integer) As String
    Dim tmp As String: tmp = ""
    Dim i As Integer
    Dim x As Integer

    If (Len(S) Mod Size) <> 0 Then
        x = Len(S) Mod Size
        tmp = tmp & Right(S, x)
        S = Left(S, Len(S) - x)
    End If

    For i = 1 To (Len(S) \ Size)
        tmp = tmp & Right(S, Size)
        S = Left(S, Len(S) - Size)
    Next

    MyReverse = tmp
End Function

Private Sub Form_Load()
MsgBox (MyReverse("AXeBib", 3))
End Sub

Changed Code after Migration

Hey, VB.NET has lot more stuff than VB6!!

Option Strict Off
Option Explicit On
Imports VB = Microsoft.VisualBasic
Friend Class Another
  Inherits System.Windows.Forms.Form
#Region "Windows Form Designer generated code "
 Public Sub New()
  MyBase.New()
  If m_vb6FormDefInstance Is Nothing Then
    If m_InitializingDefInstance Then
       m_vb6FormDefInstance = Me
    Else
     Try 
      'For the start-up form, the first instance created is the
      'default instance.
      If System.Reflection.Assembly.GetExecutingAssembly.EntryPoint.DeclaringType _
                                   Is Me.GetType Then
        m_vb6FormDefInstance = Me
      End If
     Catch
     End Try
    End If
  End If
   'This call is required by the Windows Form Designer.
   InitializeComponent()
 End Sub
 'Form overrides dispose to clean up the component list.
 Protected Overloads Overrides Sub Dispose(ByVal Disposing As Boolean)
  If Disposing Then
   If Not components Is Nothing Then
        components.Dispose()
   End If
  End If
  MyBase.Dispose(Disposing)
 End Sub
 'Required by the Windows Form Designer
 Private components As System.ComponentModel.IContainer
 Public ToolTip1 As System.Windows.Forms.ToolTip
 'NOTE: The following procedure is required by the Windows Form Designer
 'It can be modified using the Windows Form Designer.
 'Do not modify it using the code editor.
 <SYSTEM.DIAGNOSTICS.DEBUGGERSTEPTHROUGH()>
 Private Sub InitializeComponent()
   Dim resources As System.Resources.ResourceManager = New _ 
         System.Resources.ResourceManager(GetType(Another))
   Me.components = New System.ComponentModel.Container()
   Me.ToolTip1 = New System.Windows.Forms.ToolTip(components)
   Me.ToolTip1.Active = True
   Me.Text = "Form2"
   Me.ClientSize = New System.Drawing.Size(312, 206)
   Me.Location = New System.Drawing.Point(4, 30)
   Me.StartPosition = _
     System.Windows.Forms.FormStartPosition.WindowsDefaultLocation
   Me.Font = New System.Drawing.Font("Arial", 8!, _
             System.Drawing.FontStyle.Regular, _
             System.Drawing.GraphicsUnit.Point, _
             CType(0, Byte))
   Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
   Me.BackColor = System.Drawing.SystemColors.Control
   Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.Sizable
   Me.ControlBox = True
   Me.Enabled = True
   Me.KeyPreview = False
   Me.MaximizeBox = True
   Me.MinimizeBox = True
   Me.Cursor = System.Windows.Forms.Cursors.Default
   Me.RightToLeft = System.Windows.Forms.RightToLeft.No
   Me.ShowInTaskbar = True
   Me.HelpButton = False
   Me.WindowState = System.Windows.Forms.FormWindowState.Normal
   Me.Name = "Another"
 End Sub
#End Region 
#Region "Upgrade Support "
 Private Shared m_vb6FormDefInstance As Another
 Private Shared m_InitializingDefInstance As Boolean
 Public Shared Property DefInstance() As Another
   Get
     If m_vb6FormDefInstance Is Nothing OrElse m_vb6FormDefInstance.IsDisposed Then
       m_InitializingDefInstance = True
       m_vb6FormDefInstance = New Another()
       m_InitializingDefInstance = False
     End If
     DefInstance = m_vb6FormDefInstance
   End Get
   Set
       m_vb6FormDefInstance = Value
   End Set
 End Property
#End Region
'UPGRADE_NOTE: Size was upgraded to Size_Renamed. Click for more: 
'ms- help://MS.VSCC.2003/commoner/redir/redirect.htm?keyword="vbup1061"'
 Function MyReverse(ByVal S As String, ByVal Size_Renamed As Short) As String
   Dim tmp As String : tmp = ""
   Dim i As Short
   Dim x As Short

   If (Len(S) Mod Size_Renamed) <> 0 Then
     x = Len(S) Mod Size_Renamed
     tmp = tmp & VB.Right(S, x)
     S = VB.Left(S, Len(S) - x)
   End If

   For i = 1 To (Len(S) \ Size_Renamed)
     tmp = tmp & VB.Right(S, Size_Renamed)
     S = VB.Left(S, Len(S) - Size_Renamed)
   Next

   MyReverse = tmp
 End Function

 Private Sub Another_Load(ByVal eventSender As System.Object, _
    ByVal eventArgs As System.EventArgs) _
    Handles MyBase.Load
        MsgBox(MyReverse("AXeBib", 3))
 End Sub
End Class

Upgrade Report

Since it is anticipated that everything in VB may not go over to VB.NET, an upgrade report is also produced, which is a very nice thing. It also shows all the files and any facing issues in each of these files, as shown in the next and final screens. Besides some of the unsupported features mentioned in the beginning of this article, there will be other issues like graphics, Win32 APIs, legacy keywords etc.