Blog from October, 2018

gmBasic: Upgrade Engine

gmBasic is a powerful code transformation tool that reads, interprets, and rewrites VB6/ASP/COM systems for .NET (using C# or VB.NET). We are always improving gmBasic to make it more robust and flexible so that it produces cleaner, more correct results. This distribution, Version 30.76, includes several enhancements:

  • Improves the general ability to produce accurate, build-complete .NET (C# and VB.NET) systems from VB6 code (most recently making enhancements needed to upgrade a massive ERP application with 1,366 VBPs referencing 11,739 code files containing 6.1M LOC and 65 third-party-COM components)
  • Improves handling COM file references in VBP files
  • Improves handling identifiers containing international characters
  • Improves handling VB6 App.LogPath and App.LogMode

gmStudio: Upgrade Solution Development Environment

Powered by gmBasic, gmStudio is a development environment for creating high-performance, custom VB6/ASP/COM to .NET upgrade solutions. We are always adding functionality to gmStudio and making it easier to use. This distribution includes several enhancements:

  • Improves flexibility of deployment by allowing the user to specify .NET project file and folder naming conventions as part of each gmStudio project's settings
  • Improves resolution of Translation Script location for EXE tasks
  • Improves passing command line arguments for EXE tasks
  • Improves whole file search when matches are found at start of line
  • Improves project re-location logic to allow moving from one drive to another
  • Improves reporting of Warning and Note messages in the Translation Log Report
  • Improves support for MSBuild and VS2017
  • Improves ScriptRule feature so Compile\Refactor commands are automatically placed after Compile\Fix commands
  • Improves error handling when Authoring COM Interface Descriptions from a TypeLibs.lst file
  • Improves handling of international characters in script and log files
  • Corrects problem with saving user defaults changes
  • Corrects SyntaxHighlighter to color comments before strings
  • Improves efficiency of running metrics reports from New Project Wizard
  • Improves New Project Wizard to include Metrics details in Project Review results

gmSLAPI: a .NET API for Developing Advanced Upgrade Solutions

Powered by gmBasic, gmslAPI is a .NET API for automating the gmBasic upgrade engine and accessing the semantic models produced by our unique linguistic compilation technology. gmSLAPI also includes classes to facilitate integrating with gmStudio and managing complex upgrade rules. The API was updated to reflect the latest product improvements and conventions.

Sample Upgrade Rules

gmStudio ships with a collection of sample upgrade rules that can be used to add custom features to your upgrade solution. These XML documents and gmSL scripts are distributed as source that you may modify to fit your unique requirements. The sample rules were updated to reflect the latest product improvements and conventions.

  • Improves Tab Dialog Control (TabDlg32.ocx) Migration
  • Improves support for Scripting (scrrun.dll) Migration

Sample Upgrade Solutions

Great Migrations publishes a number of sample VB6/ASP upgrade solutions to illustrate the capabilities of gmStudio. The sample upgrade solutions were updated to reflect the latest product improvements and conventions.


Upgrading a real-world VB6 application typically requires replacing COM APIs with .NET APIs. gmStudio uses and open, extensible COM type system to facilitate automating these types of COM upgrades. The COM type system used by the upgrade process is declared in a set of files called Interface Description Files (IDFs). IDFs are XML text files that declare all of the elements of an API: the enumerations, classes, structs, etc. IDFs are detailed dow the level of individual method arguments. An standard set of IDFs are generated for you by gmStudio from the COM binaries used by your application. The IDF generation process usually works completely automatically, but in some cases it is necessary to manually locate and generate IDFs for atypical COM type libraries.

Standard IDFs are designed to direct the translation to use either a stub framework exposing the original COM API or an interop wrapper around the COM binary. The default is to let the gmStudio generate the stub framework and referecne it in the translated application code. This state of translation: referencing a stub framework is an initial step to facilitate building and verifying the standard translations. Once this step is completed, the IDFs may be modified to direct the translator to replace the COM APIs with some other API. The replacement techniques require modifying the IDF to change how its elements are referenced in translated code.

There are two ways to modify IDFs:

  • Modify the IDF XML files directly, or
  • Modify the IDF information with refactoring commands

This document describes how to use the second approach.  See this article for a discussion of COM Replacements by modifying IDFs directly.  

Mig.IDF Files

A Mig.IDF file is an XML text file that contains refactoring commands associated with a given IDF. Using Mig.IDF files provides a more deliberate, and arguably superior approach to organizing COM migration rules for each API. Compared to COM replacements done by modifying IDFs directly, using Mig.IDF files can be easier to create and easier to see what is being migrated because the rules are more clearly identified and explicit. Note also that Mig files are applied to the generated IDF, so re-generating the IDF will not disturb the associated Mig.IDF file.

An Example: MSComCtlLib.ProgressBar to a WinForms.ProgressBar

Let's say you want to migrate MSComCtlLib.ProgressBar to a WinForms.ProgressBar. This is a pretty easy migration as the WinForms control is very similar to the COM control.   

First you create a Mig.IDF file for the MSComCtl.ocx API taht contains progress bar. This file must be named "Mig." followed by the name of the COM IDF containing the class/control that you want to migrate in this case, the name is Mig.MSComCtl.ocx.xml. An initial version of this file is shown below.

<Refactor id="[MSComCtl.ocx]">
<Migrate location="DoNotDeclare" migName="System.Windows.Forms" />
<Migrate id="IProgressBar.Min" migName="Minimum" />
<Migrate id="IProgressBar.Max" migName="Maximum" />
<Migrate id="IProgressBar.Appearance" migStatus="mustCorrect" />
<migClass id="NetControl.ProgressBar" migName="System.Windows.Forms.ProgressBar" parent="ProgressBar">
<property id="Location" value="(Left,Top)" nPram="2" migPattern="new System.Drawing.Point(%1d, %2d)" />
<property id="Name" type="string" value="" />
<property id="Size" value="(Width,Height)" nPram="2" migPattern="new System.Drawing.Size(%1d, %2d)" />
<property id="TabIndex" type="Integer" value="TabIndex" default="0" />
<!-- NOT MAPPED for designer Appearance = System.Windows.Forms.AppearanceConstants.cc3D; -->


The Mig.IDF file should be placed in "user" folder in the project work space along with the other upgrade scripts, code, and documentation you are developing for your upgrade solution.

For this example, I placed the mig file in the usr\idf\3pc folder in my project workspace.

Next, you activate the Mig.IDF by taking advantage of gmStudio's folder conventions. For example, the following ScriptRule sets the primary configuration folder to usr\idf\3pc then loads the IDF. The tool will search for the IDF and load it then search for the Mig.IDF file and apply the refactoring commands.

<ScriptRule id="MSComCtlLib">
<Select Target="..\usr\idf\3pc"/>
<reference id="MSComCtl.ocx" />

Finally, this ScriptRule may integrated into the main translation script template using a <ScriptRule> command:

<Storage Action="Create" Identifier="%JobId%" />
<select Target="%UserFolder%" />
<Select Local="%IdfFromCodeFolder%" />
<Select System="%IdfFromIdlFolder%" />
<ScriptRule id="MSComCtlLib" /> 

<Compile Project="%SrcPath%" />
<Analyse />
<Output Status="New" Filename="%BndPath%" />
<Author />
<Storage Action="Close" />

When translator processes any VBP code that references this API, it will do so according to the modified IDF rules.

Basic Processor V30.76(07/18/18) System Build(07/18/18 5:26:53)
Loading reference:[MSComCtl.ocx] \gmClients\Client\poc\proj\idf\FromIdl\MSComCtl.ocx.xml
Loading reference:[Mig.MSComCtl.ocx] \gmClients\Client\poc\proj\usr\idf\3pc\Mig.MSComCtl.ocx.xml