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This is the second article in a series of articles that describes the various migration options of desktop/smart client applications to the Web or Cloud available using Visual WebGui as a migration tool.

In order to discuss the migration process of legacy desktop applications to the web, we should first establish that there are 3 different types of desktop applications:

1. WinForms based desktop application (C#/VB.NET). The UI layer is coded using .NET languages – the business can be .NET, COM+ or any other interop.
2. VB6 based applications. The UI layer is coded with VB 6.0.
3. Smart client or other desktop technologies (C++ MFC/ATL, Delphi, Java etc). Any other smart client technology based applications.

This document describes the migration process of VB 6.0 based desktop applications to the web using Visual WebGui's RIA platform migration tool.

VB6 Based desktop applications migration

Background
Since the WinForms development paradigm and API are actually an evolution of VB 6.0, migration to Visual WebGui which is using the exact same paradigm and API is most natural.
 

The Process
VB 6.0 based desktop applications can be transferred to web using Visual WebGui in 3 different approaches:

1. VB 6.0 Project → WinForms .NET Project → Visual WebGui .NET Project
   Migrate the VB6 using Artinsoft tools and services to a WinForms desktop application and then follow the process of WinForms applications migration as described in the first section of this document.
2. VB 6.0 UI using VB 6.0 DL/BL → Visual WebGui UI using VB 6.0 DL/BL
    The application will keep using the existing BL/DL layers as COM/COM+ VB6 based components and only the UI is mimicked within a Visual WebGui project using the productive proven tools of WinForms . The VB 6.0 to WinForms wizard of Artinsoft which exists within Visual Studio to make the process partially automatic.
3. VB 6.0 Project → Visual WebGui Project
   The entire application is mimicked within a Visual WebGui project and .NET using the productive proven tools of WinForms. The VB6 to WinForms wizard of Artinsoft which exists within Visual Studio to make the process partially automatic.

Considerations & Exceptions
Except for the considerations and exceptions mentioned in the previous section “WinForms based desktop applications”, there are two additional subjects derived from the VB history of the project:

1. The source project written in VB6 and might use non-Thread-Safe win32 or native API resources – those should be handled as potentially dangerous to the multi user web environment.
2. Threading Model: activating a COM/COM+ components coded in VB6 is using “Single Thread” or “Single Thread Apartment“ threading models; Consider using the “STAThread” attribute decoration above any method that is accessing VB6 based COM/COM+.

Summary
Migration of VB6 application to the web using Visual WebGui's migration tool has the following advantages:

• The application can keep using the existing BL/DL services – no re-write or re-engineering is required.
• UI concepts, design patterns and practices can be migrated as is.
• UI elements and API in VB6 are very similar to WinForms so that migration of the UI to Visual WebGui is quite native.
• The effort you have to make in order to accomplish a fully functional web application is measurable.

Migrating desktop applications – part 1 – WinForms to Web
Migrating desktop applications – part 3 – Smart Client Technologies to Web

Learn about Visual WebGui Migration solutions >

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