Welcome!

Microsoft Cloud Authors: David H Deans, Pat Romanski, Janakiram MSV, Jnan Dash, Andreas Grabner

Related Topics: Microsoft Cloud

Microsoft Cloud: Article

Converting VB6 to VB.NET, Part I

A Look at Your Options and When to Use Them

If you're one of the many who have VB6 code, you have three basic options: stay with VB6, convert to .NET, or rewrite from scratch. In this article, we will look at converting VB6 code to VB.NET and C#. I'll discuss when it makes sense to convert versus staying with VB6 or rewriting from scratch. I will cover what converts well and what does not, different ways to do the conversion, how to get code ready to convert, and handling issues after the conversion.

Executive Overview
First, let's get an executive-level overview of where VB6 and VB.NET are at in their life cycles. Note that when I mention VB.NET in this article, I mean all three versions (2002, 2003, 2005). When I talk about a specific version, I will specify the version (such as VB.NET 2002). With the advances in VB.NET 2003, as well as its compatibility with VB.NET 2002, there is little reason to migrate to, or stay with, VB.NET 2002. VB.NET 2005 is still an unstable beta, so the focus here will be on converting to VB.NET 2003.

For those of you who wish to stay with VB6, the key fact is that VB6 developer licenses are perpetual, so developers who have licenses can continue to develop in VB6 for as long as they wish. However, VB6 was released in January 1999 and is approaching six years of age. As a result, it is near the end of its life (VB 1.0 was originally released in 1990). VB6 no longer exists as a stand-alone product - mainstream support ends in about six months - and all support will end three years after that. Currently, to get a new VB6 license, you must either buy VB.NET and then request a VB6 downgrade disk (for about $20), or get an MSDN subscription and download it from the archives. However, I wouldn't be surprised to see these dates extended.

VB6 can be a viable option for small- to medium-sized programs with limited lifespans, for several years to come. But for large, long-term projects that will need to be maintained for a number of years, VB6 is rapidly becoming a non-option.

VB.NET was in widespread beta, with some commercial applications shipping in 2001. Release 1.0 came in 2002 and version 1.1 showed up in 2003. VB.NET is clearly ready for primetime. As a bonus, Mainsoft Corp., Mono, and Portable.NET are preparing to take VB.NET code cross-platform.

VB.NET can be cheap; many VB6 developers are MSDN members and already have access to VB.NET. The stand-alone VB.NET product is about $110, and adventuresome folk can download a free copy of VB.NET 2005 that contains the upgrade wizard at lab.msdn.microsoft.com/vs2005/get/default.aspx. A DVD (or CD) of the VS2005 Enterprise version beta can be ordered for a shipping and handling fee from the same Web page. Serious developers and corporations will typically have one of the more expensive MSDN subscriptions and access to all of this and more.

Options
If you have VB6 code, your main choices are to stay with VB6, convert the code to VB.NET or C#, or rewrite the code from scratch in VB.NET, C#, or Java. If you plan to rewrite in Java, you are probably reading the wrong article (and probably the wrong magazine; may I suggest our fine sister publication JDJ).

Whether or not to convert a program is always a case-by-case decision, driven by several competing factors such as the quality of the original code, cost, programmer availability, customer base, etc. On one hand, the only clear case where not going through at least a trial conversion would make sense is if the product is at the end of its life, with only bug fixes being implemented, and no plans for future versions. On the other hand, few large VB6 programs will convert to VB.NET without some significant rewriting. In almost all cases, I think going through at least a quick "probe" conversion is a good exercise for almost all projects - even if the converted code is not used, some valuable lessons will be learned.

Although the focus of this article will be on VB6 to VB.NET conversions, those of you moving to C# or looking at a complete VB.NET rewrite can still benefit from a conversion to VB.NET. For those of you looking at moving to C#, there are several tools (we will take a quick look at a couple of them later) that convert VB.NET to C# (and back), so it makes sense to convert to VB.NET as a step on the way to C#. If you're planning to do a complete rewrite to either VB.NET or C#, you can use the VB.NET conversion wizard to get a head start. In most programs, there are blocks of code that implement algorithms or business logic. These blocks of converted code can be pasted into a new project, speeding development for those choosing to do a complete rewrite.

Also consider that there are different levels and methods of conversion. If you have an ActiveX control written in VB6, a true conversion would be to rewrite it as a WinForm control in VB.NET. A better option might be to wrap the control in a .NET wrapper and use it from .NET while converting and testing. Shipping a VB6 ActiveX control with a .NET application can complicate the install because the VB runtime and associated files must also be installed. This is the same installation that is required if the control is installed with a VB6 application, but it is obviously more complex than the simple XCopy install of pure .NET applications.

Another way in which this ActiveX wrapper trick can be used is on forms that do not convert well, regardless of the reason. If the form can be moved to a separate project that was created as an ActiveX control project, the resulting ActiveX control can be added to a replacement form in VB6 or to a VB.NET project. Any form that can be separated from the rest of the program in this manner can be converted to an ActiveX control and used from .NET using .NET's built-in interop capabilities. In addition, we will see that most simple DLLs can be easily used directly from .NET.

In converting from VB6 to VB.NET 2003, three areas will be looked at: general VB6 code, ADO database code, and ASP Web page code. In this article, I concentrate on using the upgrade wizard to convert general VB code to VB.NET. In the future articles, I will finish general conversion issues, covering ADO, ASP, C#, and VB.NET 2005.

Before We Even Start
Remove dead code; you cannot have trouble with code you do not convert. Remove variables that are never used and subroutines that are never called. I converted one application that was large enough to have a number of associated programs, such as configuration programs, format converters, upgrade tools, and some ActiveX controls. Most of these utilities shared header files (WIN32 API declare statements and user type definitions) with the main application, but most of these programs only used a few of the functions in the headers. Other applications did not use anything in some of the headers. By removing the unused files and functions from the project, I was able to convert all the utilities much quicker. This allowed some functionality to be shown quickly, and provided the experience needed to tackle the main application.

More Stories By Dennis Hayes

Dennis Hayes is a programmer at Georgia Tech in Atlanta Georgia where he writes software for the Adult Cognition Lab in the Psychology Department. He has been involved with the Mono project for over six years, and has been writing the Monkey Business column for over five years.

Comments (2)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
With 10 simultaneous tracks, keynotes, general sessions and targeted breakout classes, Cloud Expo and @ThingsExpo are two of the most important technology events of the year. Since its launch over eight years ago, Cloud Expo and @ThingsExpo have presented a rock star faculty as well as showcased hundreds of sponsors and exhibitors! In this blog post, I provide 7 tips on how, as part of our world-class faculty, you can deliver one of the most popular sessions at our events. But before reading the...
The best way to leverage your Cloud Expo presence as a sponsor and exhibitor is to plan your news announcements around our events. The press covering Cloud Expo and @ThingsExpo will have access to these releases and will amplify your news announcements. More than two dozen Cloud companies either set deals at our shows or have announced their mergers and acquisitions at Cloud Expo. Product announcements during our show provide your company with the most reach through our targeted audiences.
In his session at @ThingsExpo, Steve Wilkes, CTO and founder of Striim, will delve into four enterprise-scale, business-critical case studies where streaming analytics serves as the key to enabling real-time data integration and right-time insights in hybrid cloud, IoT, and fog computing environments. As part of this discussion, he will also present a demo based on its partnership with Fujitsu, highlighting their technologies in a healthcare IoT use-case. The demo showcases the tracking of patie...
20th Cloud Expo, taking place June 6-8, 2017, at the Javits Center in New York City, NY, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy.
Have you ever noticed how some IT people seem to lead successful, rewarding, and satisfying lives and careers, while others struggle? IT author and speaker Don Crawley uncovered the five principles that successful IT people use to build satisfying lives and careers and he shares them in this fast-paced, thought-provoking webinar. You'll learn the importance of striking a balance with technical skills and people skills, challenge your pre-existing ideas about IT customer service, and gain new in...
With major technology companies and startups seriously embracing Cloud strategies, now is the perfect time to attend @CloudExpo | @ThingsExpo, June 6-8, 2017, at the Javits Center in New York City, NY and October 31 - November 2, 2017, Santa Clara Convention Center, CA. Learn what is going on, contribute to the discussions, and ensure that your enterprise is on the right path to Digital Transformation.
Bert Loomis was a visionary. This general session will highlight how Bert Loomis and people like him inspire us to build great things with small inventions. In their general session at 19th Cloud Expo, Harold Hannon, Architect at IBM Bluemix, and Michael O'Neill, Strategic Business Development at Nvidia, discussed the accelerating pace of AI development and how IBM Cloud and NVIDIA are partnering to bring AI capabilities to "every day," on-demand. They also reviewed two "free infrastructure" pr...
Buzzword alert: Microservices and IoT at a DevOps conference? What could possibly go wrong? In this Power Panel at DevOps Summit, moderated by Jason Bloomberg, the leading expert on architecting agility for the enterprise and president of Intellyx, panelists peeled away the buzz and discuss the important architectural principles behind implementing IoT solutions for the enterprise. As remote IoT devices and sensors become increasingly intelligent, they become part of our distributed cloud enviro...
Almost two-thirds of companies either have or soon will have IoT as the backbone of their business. Though, IoT is far more complex than most firms expected with a majority of IoT projects having failed. How can you not get trapped in the pitfalls? In his session at @ThingsExpo, Tony Shan, Chief IoTologist at Wipro, will introduce a holistic method of IoTification, which is the process of IoTifying the existing technology portfolios and business models to adopt and leverage IoT. He will delve in...
It is one thing to build single industrial IoT applications, but what will it take to build the Smart Cities and truly society changing applications of the future? The technology won’t be the problem, it will be the number of parties that need to work together and be aligned in their motivation to succeed. In his Day 2 Keynote at @ThingsExpo, Henrik Kenani Dahlgren, Portfolio Marketing Manager at Ericsson, discussed how to plan to cooperate, partner, and form lasting all-star teams to change the...
SYS-CON Events announced today that LeaseWeb USA, a cloud Infrastructure-as-a-Service (IaaS) provider, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. LeaseWeb is one of the world's largest hosting brands. The company helps customers define, develop and deploy IT infrastructure tailored to their exact business needs, by combining various kinds cloud solutions.
The buzz continues for cloud, data analytics and the Internet of Things (IoT) and their collective impact across all industries. But a new conversation is emerging - how do companies use industry disruption and technology enablers to lead in markets undergoing change, uncertainty and ambiguity? Organizations of all sizes need to evolve and transform, often under massive pressure, as industry lines blur and merge and traditional business models are assaulted and turned upside down. In this new da...
SYS-CON Events announced today that Outlyer, a monitoring service for DevOps and operations teams, has been named “Bronze Sponsor” of SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. Outlyer is a monitoring service for DevOps and Operations teams running Cloud, SaaS, Microservices and IoT deployments. Designed for today's dynamic environments that need beyond cloud-scale monitoring, we make monitoring effortless so you...
There are 66 million network cameras capturing terabytes of data. How did factories in Japan improve physical security at the facilities and improve employee productivity? Edge Computing reduces possible kilobytes of data collected per second to only a few kilobytes of data transmitted to the public cloud every day. Data is aggregated and analyzed close to sensors so only intelligent results need to be transmitted to the cloud. Non-essential data is recycled to optimize storage.
SYS-CON Events announced today that Conference Guru has been named “Media Sponsor” of SYS-CON's 20th International Cloud Expo, which will take place on June 6–8, 2017, at the Javits Center in New York City, NY. A valuable conference experience generates new contacts, sales leads, potential strategic partners and potential investors; helps gather competitive intelligence and even provides inspiration for new products and services. Conference Guru works with conference organizers to pass great dea...
“We're a global managed hosting provider. Our core customer set is a U.S.-based customer that is looking to go global,” explained Adam Rogers, Managing Director at ANEXIA, in this SYS-CON.tv interview at 18th Cloud Expo, held June 7-9, 2016, at the Javits Center in New York City, NY.
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at Cloud Expo, Ed Featherston, a director and senior enterprise architect at Collaborative Consulting, discussed the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at 20th Cloud Expo, Ed Featherston, director/senior enterprise architect at Collaborative Consulting, will discuss the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
SYS-CON Events announced today that DatacenterDynamics has been named “Media Sponsor” of SYS-CON's 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY. DatacenterDynamics is a brand of DCD Group, a global B2B media and publishing company that develops products to help senior professionals in the world's most ICT dependent organizations make risk-based infrastructure and capacity decisions.
"Matrix is an ambitious open standard and implementation that's set up to break down the fragmentation problems that exist in IP messaging and VoIP communication," explained John Woolf, Technical Evangelist at Matrix, in this SYS-CON.tv interview at @ThingsExpo, held Nov 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA.