Welcome!

.NET Authors: Jim Kaskade, Adine Deford, TJ Randall, Sandi Mappic, Ivan Antsipau

Related Topics: .NET

.NET: 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
SYS-CON Events announced today that SOA Software, an API management leader, will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. SOA Software is a leading provider of API Management and SOA Governance products that equip business to deliver APIs and SOA together to drive their company to meet its business strategy quickly and effectively. SOA Software’s technology helps businesses to accelerate their digital channels with APIs, drive partner adoption, monetize their assets, and achieve a...
SYS-CON Events announced today that Aria Systems, the recurring revenue expert, has been named "Bronze Sponsor" of SYS-CON's 15th International Cloud Expo®, which will take place on November 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Aria Systems helps leading businesses connect their customers with the products and services they love. Industry leaders like Pitney Bowes, Experian, AAA NCNU, VMware, HootSuite and many others choose Aria to power their recurring revenue business and deliver exceptional experiences to their customers.
SYS-CON Events announced today that AgilePoint, the leading provider of Microsoft-centric Business Process Management software, will exhibit at SYS-CON's 2nd International @ThingsExpo which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. AgilePoint is the leading provider of Microsoft-based Business Process Management (BPM) software products, has 1,300+ on-premise and cloud deployments in 25+ countries and provides the same advanced BPM feature set as J2EE vendors like IBM and Appian for the Microsoft .NET native environment. AgilePoint customer...
The Internet of Things (IoT) promises to evolve the way the world does business; however, understanding how to apply it to your company can be a mystery. Most people struggle with understanding the potential business uses or tend to get caught up in the technology, resulting in solutions that fail to meet even minimum business goals. In his session at Internet of @ThingsExpo, Jesse Shiah, CEO / President / Co-Founder of AgilePoint Inc., will show what is needed to leverage the IoT to transform your business. He will discuss opportunities and challenges ahead for the IoT from a market and tec...
SYS-CON Events announced today that Utimaco will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Utimaco is a leading manufacturer of hardware based security solutions that provide the root of trust to keep cryptographic keys safe, secure critical digital infrastructures and protect high value data assets. Only Utimaco delivers a general-purpose hardware security module (HSM) as a customizable platform to easily integrate into existing software solutions, embed business logic and build s...
One of the biggest challenges when developing connected devices is identifying user value and delivering it through successful user experiences. In his session at Internet of @ThingsExpo, Mike Kuniavsky, Principal Scientist, Innovation Services at PARC, will describe an IoT-specific approach to user experience design that combines approaches from interaction design, industrial design and service design to create experiences that go beyond simple connected gadgets to create lasting, multi-device experiences grounded in people’s real needs and desires.
SYS-CON Events announced today that TeleStax, the main sponsor of Mobicents, will exhibit at Internet of @ThingsExpo, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. TeleStax provides Open Source Communications software and services that facilitate the shift from legacy SS7 based IN networks to IP based LTE and IMS networks hosted on private (on-premise), hybrid or public clouds. TeleStax products include Restcomm, JSLEE, SMSC Gateway, USSD Gateway, SS7 Resource Adaptors, SIP Servlets, Rich Multimedia Services, Presence Services/RCS, Diame...
Samsung VP Jacopo Lenzi, who headed the company's recent SmartThings acquisition under the auspices of Samsung's Open Innovaction Center (OIC), answered a few questions we had about the deal. This interview was in conjunction with our interview with SmartThings CEO Alex Hawkinson. IoT Journal: SmartThings was developed in an open, standards-agnostic platform, and will now be part of Samsung's Open Innovation Center. Can you elaborate on your commitment to keep the platform open? Jacopo Lenzi: Samsung recognizes that true, accelerated innovation cannot be driven from one source, but requires a...
The Internet of Things will greatly expand the opportunities for data collection and new business models driven off of that data. In her session at Internet of @ThingsExpo, Esmeralda Swartz, CMO of MetraTech, will discuss how for this to be effective you not only need to have infrastructure and operational models capable of utilizing this new phenomenon, but increasingly service providers will need to convince a skeptical public to participate. Get ready to show them the money! Speaker Bio: Esmeralda Swartz, CMO of MetraTech, has spent 16 years as a marketing, product management, and busin...
Things are being built upon cloud foundations to transform organizations. This CEO Power Panel at 15th Cloud Expo, moderated by Roger Strukhoff, Cloud Expo and @ThingsExpo conference chair, will address the big issues involving these technologies and, more important, the results they will achieve. How important are public, private, and hybrid cloud to the enterprise? How does one define Big Data? And how is the IoT tying all this together?
We certainly live in interesting technological times. And no more interesting than the current competing IoT standards for connectivity. Various standards bodies, approaches, and ecosystems are vying for mindshare and positioning for a competitive edge. It is clear that when the dust settles, we will have new protocols, evolved protocols, that will change the way we interact with devices and infrastructure. We will also have evolved web protocols, like HTTP/2, that will be changing the very core of our infrastructures. At the same time, we have old approaches made new again like micro-services...
SYS-CON Events announces a new pavilion on the Cloud Expo floor where WebRTC converges with the Internet of Things. Pavilion will showcase WebRTC and the Internet of Things. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devices--computers, smartphones, tablets, and sensors – connected to the Internet by 2020. This number will continue to grow at a rapid pace for the next several decades.
The only place to be June 9-11 is Cloud Expo & @ThingsExpo 2015 East at the Javits Center in New York City. Join us there as delegates from all over the world come to listen to and engage with speakers & sponsors from the leading Cloud Computing, IoT & Big Data companies. Cloud Expo & @ThingsExpo are the leading events covering the booming market of Cloud Computing, IoT & Big Data for the enterprise. Speakers from all over the world will be hand-picked for their ability to explore the economic strategies that utility/cloud computing provides. Whether public, private, or in a hybrid form, clo...
SYS-CON Events announced today that Gridstore™, the leader in software-defined storage (SDS) purpose-built for Windows Servers and Hyper-V, will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Gridstore™ is the leader in software-defined storage purpose built for virtualization that is designed to accelerate applications in virtualized environments. Using its patented Server-Side Virtual Controller™ Technology (SVCT) to eliminate the I/O blender effect and accelerate applications Gridsto...
SYS-CON Events announced today that Red Hat, the world's leading provider of open source solutions, will exhibit at Internet of @ThingsExpo, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Red Hat is the world's leading provider of open source software solutions, using a community-powered approach to reliable and high-performing cloud, Linux, middleware, storage and virtualization technologies. Red Hat also offers award-winning support, training, and consulting services. As the connective hub in a global network of enterprises, partners, a...
As the Internet of Things unfolds, mobile and wearable devices are blurring the line between physical and digital, integrating ever more closely with our interests, our routines, our daily lives. Contextual computing and smart, sensor-equipped spaces bring the potential to walk through a world that recognizes us and responds accordingly. We become continuous transmitters and receivers of data. In his session at Internet of @ThingsExpo, Andrew Bolwell, Director of Innovation for HP’s Printing and Personal Systems Group, will discuss how key attributes of mobile technology – touch input, senso...
The Internet of Things (IoT) is making everything it touches smarter – smart devices, smart cars and smart cities. And lucky us, we’re just beginning to reap the benefits as we work toward a networked society. However, this technology-driven innovation is impacting more than just individuals. The IoT has an environmental impact as well, which brings us to the theme of this month’s #IoTuesday Twitter chat. The ability to remove inefficiencies through connected objects is driving change throughout every sector, including waste management. BigBelly Solar, located just outside of Boston, is trans...
Connected devices and the Internet of Things are getting significant momentum in 2014. In his session at Internet of @ThingsExpo, Jim Hunter, Chief Scientist & Technology Evangelist at Greenwave Systems, will examine three key elements that together will drive mass adoption of the IoT before the end of 2015. The first element is the recent advent of robust open source protocols (like AllJoyn and WebRTC) that facilitate M2M communication. The second is broad availability of flexible, cost-effective storage designed to handle the massive surge in back-end data in a world where timely analytics...
Internet of @ThingsExpo Silicon Valley announced on Thursday its first 12 all-star speakers and sessions for its upcoming event, which will take place November 4-6, 2014, at the Santa Clara Convention Center in California. @ThingsExpo, the first and largest IoT event in the world, debuted at the Javits Center in New York City in June 10-12, 2014 with over 6,000 delegates attending the conference. Among the first 12 announced world class speakers, IBM will present two highly popular IoT sessions, which will take place November 4-6, 2014 at the Santa Clara Convention Center in Santa Clara, Calif...
From a software development perspective IoT is about programming "things," about connecting them with each other or integrating them with existing applications. In his session at @ThingsExpo, Yakov Fain, co-founder of Farata Systems and SuranceBay, will show you how small IoT-enabled devices from multiple manufacturers can be integrated into the workflow of an enterprise application. This is a practical demo of building a framework and components in HTML/Java/Mobile technologies to serve as a platform that can integrate new devices as they become available on the market.