* Updated with follow up post on technical information in response to the comments.

While I’m not a lawyer, my team owns Visual Studio Express and I wanted to respond to the concerns expressed by some over our recent communications with Jamie Cansdale of TestDriven.NET. TestDriven.NET is a 3rd party add-in to Visual Studio that provides testing functionality in Visual Studio. To be clear, we have no issue with the product (or Jamie for that matter), or its sale for use in professional versions of Visual Studio. However, Jamie has also made available a version of his product that extends the Visual Studio Express Editions which is a direct violation of both the EULA and “ethos” of the Express product line.

As you may remember from my previous posts, Visual Studio Express was a labor of love. It was a small miracle getting Express to be available both for free and for commercial use for customers let alone the engineering work to get it up and running, We made a business decision to not allow 3rd party extensibility in Express. The reason we’re able to offer Express for free and even let developers build commercial applications with Express is because we limit 3rd party extensibility of Express, specifically by removing support macros, add-ins, and VSIP packages. Unfortunately, in this one instance, we have one company that chose to exceed the license grant and develop additional features into the Express products that are not allowed. Additionally we have over 300 VSIP partners with over 1,000 legal Visual Studio extensions that cannot extend Express. It doesn’t make business sense when our biggest and best partners are legally unable to extend Express, yet Jamie’s company can.

As for Jamie, we’ve been asking him in multiple emails and conference calls to stop extending (just Express) since before Visual Studio 2005 even shipped. We even got the General Manager of Visual Studio to personally talk to him on the phone to plead with him to remove Express extensibility. Closely following that, Jamie took the violations to heart and removed Visual Studio Express extensibility for several months. Only recently did he decide to add Express support back to TestDriven.NET and only after another round of conversations and close to two years of trying to avoid escalating this situation, we felt compelled to deliver our message in a different form.

The Express Customer
The vast majority of our customer base, now with 14 million downloads, isn’t even professional developers, its non-professionals. In fact over 80% of Express registrants don’t describe themselves as a “developer”. From a total number perspective, beginners are the largest segment of Express customers and they still find Express too complex, it has too many features, and they see development as a means to an end (I just want to create my kids soccer league Web site). Our Express customers haven't been asked for unit testing or extensiblity in much the same way as I didn't ask or even know to ask when I grew up programming BASIC on an Apple IIe. Heck even professional developers with years of programming experience can't program FizzBuzz

It’s unfortunate that this happened, but as you can see, we have been very patient with Jamie and it’s our hope he will remain in compliance of the Visual Studio Express Editions license agreement.

If the choice was between not ever having released Visual Studio Express (or not releasing it in the future) or having Visual Studio Express with an explicit limitation to block extensibility, which would you chose? As an advocate for the (wholly neglected) beginner customer and as an employee that understands Microsoft is a business at the end of the day, it seems like a perfectly reasonable tradeoff to make that, in the end, provides the best tools possible to an entire class of customer that may never have picked up programming without it.