In it March issue, Visual Studio Magazine published an in-depth article about legacy migrations called “Unlocking Legacy Code”. This article talks about the challenges faced by companies migrating from Visual Basic 6.0 to .NET, the drivers behind these migrations and the pros and cons of using an automated migration solution.
The article uses BEMAS Software as a case study for successful migration products. I am incredibly happy they are doing as well as they are with the conversion – they are using our tools, and I visited BEMAS about a year and a half ago to train them on the VBUC and help them plan the migration project. I remember they had a lot of conditional statements (by “a lot”, we are talking thousands of different combinations), as mentioned in the article:
"We also ran into some issues with the conversion tool because early on in the VB code we did a lot of #ifs, which means that the code acts differently depending on how you compile it," Pownall adds. BEMAS worked with ArtinSoft so that VBUC would recognize those instances and convert the code correctly.
It was quite a challenge to get it to convert, since the default behavior of the VBUC is to convert the code inside the conditional statement that evaluates to “TRUE”. Commenting out the conditionals wasn’t going to work either, since that would cause multiple variable declarations and other semantic errors that caused issues during the migration of this particular code. In the end we worked together with BEMAS, and with heavy involvement of the VBUC development team, we managed to modify the tool enough to get the code converted correctly.
Another very interesting item mentioned by Steve Pownall in the article, that I want to talk about some more, is the fact that even though the code came through very cleanly, it didn’t have the .NET architecture they were aiming for so they had to “The dev team had to massage or opted to rewrite the rest of the codebase manually in C# and .NET 3.5 using VS2008.”. This is a very important point, since the overall architecture of the code will remain as it was in VB6.0. The migration, however, gets you quickly to a stable .NET codebase that you can then rework to make it take advantage of the latest features of the .NET Framework. In our experience, this path (migrate, then enhance) is the one with the lowest risk, and it allows you to reduce the time to market for your applications by a wide margin. This is important to keep in mind, since we, as developers, always want to improve the code base – it is part of our professional formation, and I would say, part of our nature – but we sometimes fail to grasp the additional risk this implies. The migration is very controlled process, that gets you predictable results in a short time. Enhancing the application after the migration may seem like duplicating work (and indeed, there are enhancements that can be done during the migration process) but it guarantees that you will get a .NET in the allocated timeframe and budget, not to mention the cost advantage.
Read the complete article, Unlocking Legacy Code at Visual Studio Magazine.
One very common requirement for migration projects is to adapt certain error handling patterns used in a customer’s Visual Basic 6.0 code to the structured error handling provided by .NET, cleaning up the code, improving its maintainability, and, whenever possible, complying with .NET best practices.
The VBUC already converts several commonly used error handling patterns, such as the ones described in this old post. There are, however, situations where the VBUC is not able to recognize a pattern. these usually involve Goto statements, On Error Resume Next, Resume Next or some other construct usually associated with “spaghetti code”. When one of these patterns is encountered, the VBUC does a very basic transformation and generates an EWI so it can be cleaned up through manual intervention later on, such as in the following example:
|
Visual Basic 6.0 Code |
.NET Code |
Private Function <NAME>(<PARAMS>) As <TYPE>
Const MethodName As String = "<NAME>"
On Error GoTo ErrorLabel
<STATEMENTS 1>
On Error GoTo <LABEL>
<STATEMENTS 2>
CleanUp:
<STATEMENTS 3>
Exit Function
<LABEL>:
<STATEMENTS 4>
LogError(MethodName)
Err.Raise 16, , MethodName
ErrorLabel:
<STATEMENTS 5>
LogError(MethodName)
Err.Raise Err.Number, , MethodName
End Function
|
private <TYPE> <NAME>()
{
const string MethodName = "<NAME>";
//UPGRADE_TODO: (1065)
Error handling statement
(On Error Goto) could not be converted.
More Information:
http://www.vbtonet.com/ewis/ewi1065.aspx
NotUpgradedHelper.NotifyNotUpgradedElement(
"On Error Goto Label (ErrorLabel)");
<STATEMENTS 1>
try
{
<STATEMENTS 2>
<STATEMENTS 3>
return result;
}
catch (Exception ex)
{
<STATEMENTS 4>
LogError(MethodName);
throw new System.Exception(
((int) 16).ToString() +
", " + String.Empty +
", " + MethodName);
ErrorLabel:
<STATEMENTS 5>
//UPGRADE_WARNING: (2081)
Err.Number has a new behavior.
More Information:
http://www.vbtonet.com/ewis/ewi2081.aspx
LogError(MethodName);
throw new System.Exception(
Information.Err().Number.ToString() +
", " + String.Empty +
", " + MethodName);
return result;
}
} |
Most of the time it is possible to generate a solution that will correctly convert the error handling pattern, maintaining functional equivalence and meeting any additional coding guidelines from our customers. For the previous example, The VBUC can be customized so the generated code looks as follows:
try
{
try
{
<STATEMENTS 1>
}
catch (Exception ex){
<STATEMENTS 5>
throw;
}
try
{
<STATEMENTS 2>
}
catch (Exception <LABEL>Ex)
{
<STATEMENTS 4>
<LABEL>Ex.Data.Add("ERROR",16);
throw;
}
}
finally
{
<STATEMENTS 3>
}
This example makes some assumptions on the nature of the code and on the intention of the original VB6.0 developer, in particular:
- Errors raised by <STATEMENTS 1> should be handled by <STATEMENTS 5>
- Errors raised by <STATEMENTS 2> should be handled by <STATEMENTS 4>
- <STATEMENTS 3> is cleanup code that should always be executed
- The Exception needs to be thrown again without loosing any information
This is just an example, but the intention is to show what type of customizations can be done. The VBUC transformation engine is very powerful, and, as long as a pattern can be identified, can help you automate the solution to most VB6.0 problems.
Here is a quick way to know if a binary file (*.exe, *.dll, *.ocx, …) has a dependency on the Visual Basic 6.0 Runtime. The trick is to use the Dependency Walker tool to see its dependencies. The dependency you are looking for is the Visual Basic 6.0 runtime library (msvbvm60.dll), and it appears on the tree if you are dealing with a VB6.0 binary:
If you are concerned about the VB6.0 runtime not being supported after Windows Server 2008 and Windows 7, this is a trick that can help you decide whether to keep a particular third party ActiveX component in your application through COM Interop after migrating to the .NET Framework or to start looking for a replacement in case the runtime is no longer available (and thus the component will no longer work).
Dependency Walker is a freeware tool that was included with Visual Studio 6.0, is included in the Windows Support Tools and can be downloaded from the Dependency Walker homepage.
The business-oriented newspaper, El Financiero, just published an article talking about the advantages of performing a migration instead of a manual rewrite. The article talks about how Banamex (part of Citigroup) saved an estimated 80% of the cost when compared to rewriting their 125 applications, totaling over 5 million lines of code. It also talks about the advantages of being in .NET, including how it allows customers to rapidly respond to changes in market conditions.
You can read the original article in Spanish at the following link: Cambiar el software en estos tiempos de crisis or read the Google Translation in English. You can also check out the Banamex/Citigroup case study at the following link: Banamex - Citigroup turns to ArtinSoft to ensure compliance and business continuity through massive migration to C#.NET
Yesterday TechNewsWorld published an article called Planning a Migration Route From Visual Basic 6 to .Net, which discusses some aspects of a report by the Aberdeen Group. The article contains lots of valuable information for those of you considering moving your VB6.0 applications to .NET, by giving a very good idea on the best practices performed by the “Best-in-Class” organizations. I wanted to touch briefly on some of the points from the article, and how it matches our experience helping Fortune/Global 1000 companies upgrade their applications to the latest technology.
Something that is consistent with what we’ve seen is that 33% of the respondents from Best-in-Class and 15% of the “All Others” organizations engage a third party to assist with the migration. We at ArtinSoft, with our Consulting Services group, and along with our world-wide partners, have seen this as a growing trend, and have accumulated a vast a mount of experience that can be leveraged by these organizations to move away from legacy environments.
Also, as part of our migration methodology, we promote a controlled process that first brings your VB6.0 application up to Functional Equivalence in .NET, and then you can use this as a base to enhance an improve your investment. For many clients we also use the extensibility capabilities of the Visual Basic Upgrade Companion to prepare the source code for these enhancements by automating specific architectural modifications required by our customers. These modifications represent an enhancement in itself, and also leave the code ready for further changes by making sure it meets all the practices and coding standards of the organization. The Vertex Omiga and Supervisor Case Studies are a good example in this regard – and we’ve done other migrations with even more important customizations that, unfortunately, I can’t mention directly.
Finally, I want to quote the following text from near the end of the article:
“The research shows that Best-in-Class companies are six times more likely than all other companies to use code conversion or automated porting tools in order to help accelerate part of the migration process.”
You can read our case studies that show this is in fact the case, and we have helped many organizations save time and resources when performing migrations aided by using the Visual Basic Upgrade Companion.
As you are probably well aware, along with the release of Windows 7 RC came some big news that affect Visual Basic 6.0 applications: Professional and Ultimate Editions of Windows 7 will feature a Windows XP Mode for backwards compatibility with legacy applications. This means that even if you are using components that have issues with Windows 7, you will be able to run your VB6.0 application on the new operating system, albeit within a Windows XP virtual machine.
It is important to mention that the VB team over at Microsoft was already making sure the IDE and VB6 runtime would work on Windows 7, as I commented before (second comment on that post) based on the Support Statement for Visual Basic 6.0 on Windows Vista, Windows Server 2008 and Windows 7:
The Visual Basic team is committed to “It Just Works” compatibility for Visual Basic 6.0 applications on Windows Vista, Windows Server 2008 and Windows 7.
The Visual Basic team’s goal is that Visual Basic 6.0 applications that run on Windows XP will also run on Windows Vista, Windows Server 2008 and Windows 7. The Visual Basic team is also committed to the Visual Basic 6.0 development environment running on Windows Vista, Windows Server 2008 and Windows 7.
The objective of XP Mode is clearly to move forward the Windows architecture to the latest technologies, free of all the legacy bits required to maintain compatibility of old applications (read the History posts at the The Old New Thing blog for examples), while at the same time it allows developers to smoothly upgrade their applications without the threat of the application not working in the new OS. It is basically a compromise of old vs. new. And it is very easy to draw parallels between XP Mode and the approach taken by Apple, first with Classic and then with Rosetta, to smooth the transition to new platforms. But as was the case in those scenarios, Classic was eventually phased out, and Rosetta will eventually be as well.
I personally think that this technology may end up being around for a while, and may even end up included in the next versions of Windows if there is enough customer demand for it. This has to be the same technology used in their Microsoft Enterprise Desktop Virtualization (MED-V) solution, targeted towards enterprise customers:
“Microsoft Enterprise Desktop Virtualization (MED-V) provides deployment and management of virtual Windows desktops to enable key enterprise scenarios. MED-V 1.0 helps enterprises upgrade to the latest version of Windows even when some applications are not yet compatible.”
Even in the scenario that XP Mode is supported for a long time, you still have to consider it as something that can be used for a smooth transition while you upgrade your applications to the .NET Framework, and not as an excuse for not upgrading. It can help you plan a gradual migration, were you first start migrating certain modules while leaving others in VB6, with tools like the Interop Forms Toolkit. And keep in mind that even though the application will run, the IDE is simply not supported anymore and neither are most controls that cause compatibility issues. And at the same time you will be missing the benefits of using the latest technologies and the increased productivity of the .NET Framework.
This week Microsoft updated its support statement for Visual Basic 6.0 to include the upcoming Windows 7. Even though the original idea was to not support VB6 in Windows 7, given the outstanding demand, the runtime WILL BE included in the OS.
To summarize, the support status of the different Visual Basic 6.0 components is:
- Visual Basic 6.0 IDE: Unsupported as of April 8, 2008.
- Visual Basic 6.0 Runtime: Supported for the lifetime of Windows Vista, Server 2008 and 7. *This is the big change in the Support Statement*.
- Visual Basic 6.0 Runtime Extended Files: The supported versions are here.
Even though the runtime components will be supported in Windows 7, it is important to consider the implications of the IDE not being supported (as I described in this post). There are also additional advantages of moving to .NET such as 64-bit support (VB6 apps are 32-bit only) and all the productivity, maintainability and deployment gains provided by the platform.
One of the key features of the Visual Basic Upgrade Companion (one that is not present in the Developer Edition, BTW) is that it’s functionality can be customized and extended. By doing this, developers working on a migration can have the VBUC do as much of the work as possible for them, minimizing the manual work and producing a higher quality product that satisfy both the developer’s and end user’s expectations. Performing repetitive changes to, for example, replace the data access components from VB6 (ADO/RDO/DAO) with native .NET data access (ADO.NET), is better done by the VBUC at migration time. This also applies to particular programming patterns used by organizations that need to be replaced by .NET-native patterns, and to coding conventions that vary between VB6 and .NET languages.
The Visual Basic Upgrade Companion includes three mechanisms to customize the generated code: Migration Profiles, Custom Maps and Additional Customizations.
Migration Profiles
A new feature that was introduced in version 2.0 of the Visual Basic Upgrade Companion, it gives end users control over which features and transformations to use for a particular migration, by using the concept of Migration Profiles. These profiles provide two types of rules that can be switched on/off. The first type, Code Conversion Rules, that deal with patterns applied to the code, such as generating structure error handling (try…catch) from On Error…Goto statements or applying commonly used naming conventions to the code. The second type is called Component Maps, and deal with translations from from one ActiveX component, such as a status bar or a grid, to a native version of the component.
Profiles are managed through the Profile Maintenance screen:
Custom Maps
The Visual Basic Upgrade Companion includes a “mapping” mechanism that allow end-users of the tool to define the transformation of one element of a library used in the VB6 code to a member of an assembly in .NET. This allows a migration team to identify and implement time-saving transformations, and, when combined with the implementation of an adapter for the .NET component, can speed up the migration process dramatically.
The Mappings are defined through a GUI editor launched from within the VBUC itself:
Once the mappings are defined, they can be switched on and off in the migration through the Migration Profile Maintenance Window:
Additional Customizations
ArtinSoft’s VBUC development team can also include additional complex rules in the VBUC, including customizations for items such as error handling patterns, architectural modifications, and others. These customizations also include mapping COM controls to in-house libraries, or force in-house naming conventions. This was a decision point for one of clients in the United Kingdom, Vertex Financial Services, as documented in the Vertex Omiga case study:
“Vertex decided to migrate the Omiga application to C# using a customized version of the Visual Basic Upgrade Companion, a tool developed by ArtinSoft based on artificial intelligence technology. ArtinSoft was highly recommended by Microsoft UK, and the customization of this migration tool enabled Vertex to automatically convert coding patterns and meet its preferred standards.”
These type of customizations require some modifications to the VBUC that can only be performed by ArtinSoft’s in-house team. It is a very valuable option that allows companies to get a an end product which furthers increases the return on investment from the migration.
Earlier this week we launched an joint initiative with Microsoft and Avanade in the UK for helping Visual Basic 6.0 developers move their applications to .NET. The initiative consists of several parts:
The initiative is UK-only at the time, but if you want to take advantage of these time-limited deals feel free to contact us. The press release for the campaign can be found here and at our website. Eric Nelson from Microsoft has been heavily involved - you can read his blog post on the initiative here.
The campaign has been well received so far. In the two days since launch, we already have several leads interested in both offerings!!
Jointly with the Visual Basic 6.0 migration campaign we are launching in the UK, today we released the Visual Basic Upgrade Companion Developer Edition. This is a scaled down version of the Visual Basic Upgrade Companion, targeted at individual developers that want to migrate their Visual Basic 6.0 applications as fast and painlessly as possible. It has a license that is valid for three months and allows you to migrate an application of up to 50,000 lines of code.
The VBUC Developer Edition does have some fewer features than the fully-fledged Visual Basic Upgrade Companion. All the features that we decided to include in the Developer Edition, however, are targeted towards automating as much of the migration process as possible. So, we left out features that have been introduced by the request of our enterprise customers over the 7+ years the tool has been on the market (yep, we were already doing VB6 migrations before the official release of .NET - and it wasn't all fun with the Betas). We made it so that getting an application up and running in C# or VB.NET is as simple as possible.
Here you can see the VBUC Developer Edition in action (video recorded by yours truly :) ):
And, as an introductory offer, The VBUC Developer Edition will only cost £199 for a limited time. So why wait?