UPDATE: The .NET team removed the platform limitations.

Let me start by giving some kudos to the Microsoft BCL (Base Class Library) team. They’ve been doing a great job of shipping useful libraries lately. Here’s a small sampling on Nuget:

However, one trend I’ve noticed is that the released versions of most of these packages have a platform limitation in the EULA (the pre-release versions have an “eval-only” license which do not limit platform, but do limit deployment for production use). At this point I should remind everyone I’m not a lawyer and this is not legal advice blah blah blah.

Here’s an excerpt from section 2. c. in the released HttpClient license, emphasis mine:

a. Distribution Restrictions. You may not

  • alter any copyright, trademark or patent notice in the Distributable Code;
  • use Microsoft’s trademarks in your programs’ names or in a way that suggests your programs come from or are endorsed by Microsoft;
  • distribute Distributable Code to run on a platform other than the Windows platform;

I think this last bullet point is problematic and should be removed.

Why should they?

I recently wrote the following tweet in response to this trend:

Dear Microsoft BCL team. Please remove the platform limitation on your very cool libraries. Love, cross-platform .NET devs.

And a Richard Burte tweeted back:

And that pays the rent how exactly?

Great question!

There is this sentiment among many that the only reason to make .NET libraries cross platform or open source is just to appease us long haired open source hippies.

Well first, let me make it crystal clear that I plan to get a haircut very soon. Second, the focus of this particular discussion is the platform limitation on the compiled binaries. I’ll get to the extra hippie open source part later.

There are several reasons why removing the platform limitation benefits Microsoft and the .NET team.

It benefits Microsoft’s enterprise customers

Let’s start with Microsoft’s bread and butter, the enterprise. There’s a growing trend of enterprises that support employees who bring their own devices (BYOD) to work. As Wikipedia points out:

BYOD is making significant inroads in the business world, with about 75% of employees in high growth markets such as Brazil and Russia and 44% in developed markets already using their own technology at work.

Heck, at the time I was an employee, even Microsoft supported employees with iPhones connecting to Exchange to get email. I assume they still do, Ballmer pretending to break an iPhone notwithstanding.

Microsoft’s own software supports cross-platform usage. Keeping platform limitations on their .NET code hamstrings enterprise developers who want to either target the enterprise market or want to make internal tools for their companies that work on all devices.

It’s a long play benefit to Windows 8 Phone and Tablet

While developing Windows 8, Microsoft put a ton of energy and focus into a new HTML and JavaScript based development model for Windows 8 applications, at the cost of focus on .NET and C# in that time period.

The end result? From several sources I’ve heard that something like 85% of apps in the Windows app store are C# apps.

Now, I don’t think we’re going to see a bunch of iOS developers suddenly pick up C# in droves and start porting their apps to work on Windows. But there is the next generation to think of. If Windows 8 devices can get enough share to make it worthwhile, it may be easier to convince this next generation of developers to consider C# for their iOS development and port to Windows cheaply. Already, with Xamarin tools, using C# to target iOS is a worlds better environment than Objective-C. I believe iOS developers today tolerate Objective-C because it’s been so successful for them and it was the only game in town. As Xamarin tools get more notice, I don’t think the next generation will tolerate the clumsiness of the Objective-C tools.

There’s no good reason not to

Ok, this isn’t strictly speaking a benefit. But it speaks to a benefit.

The benefit here is that when Microsoft restricts developers without good reason, it makes them unhappy.

If you recall, Ballmer is the one who once went on stage to affirm Microsoft’s focus on developers! developers! developers! through interpretive dance.


Unless there’s something I’m missing (and feel free to enlighten me!), there’s no good reason to keep the platform restriction on most of these libraries. In such cases, focus on the developers!

At a recent Outercurve conference, Scott Guthrie, a corporate VP at Microsoft in change of the Azure Development platform told the audience that his team’s rule of thumb with new frameworks is to default it to open source unless they have a good reason not to.

The Azure team recognizes that a strategy that requires total Windows hegemony will only lead to tears. Microsoft can succeed without having Windows on every machine. Hence Azure supports Linux, and PHP, and other non-Microsoft technologies.

I think the entire .NET team should look to what the Azure team is doing in deciding what their strategy regarding licensing should be moving forward. It makes more developers happy and costs very little to remove that one bullet point from the EULA. I know, I’ve been a part of a team that did it. We worked to destroy that bullet with fire (among others) in every ASP.NET MVC EULA.

Update: It looks like I may have overstated this. Licenses for products are based on templates. Typically a product team’s lawyer will grab a template and then modify it. So with ASP.NET MVC 1 and 2, we removed the platform restriction in the EULA. But it looks like the legal team switched to a different license template in ASP.NET MVC 3 and we forgot to remove the restriction. That was never the intention. Shame on past Phil. Present Phil is disappointed.

At least in this case, the actual source code is licensed under the Apache 2.0 license developers have the option to compile and redistribute, making this a big inconvenience but not a showstopper.

Next Steps

I recently commented on a BCL blog post suggesting that the team remove the platform limitation on a library. Immo Landwerth, a BCL Program Manager responded with a good clarifying question:

Thanks for sharing your concerns and the candid feedback. You post raised two very different items:

​(1) Windows only restriction on the license of the binaries

​(2) Open sourcing immutable collections

From what I read, it sounds you are more interested in (1), is this correct?

The post he refers to is actually one that Miguel de Icaza wrote when MEF came out with a license that had a platform restriction entitled Avoid the Managed Extensibility Framework. Fortunately, that was quickly corrected in that case.

But now we seem to be in a similar situation again.

Here was my response:

@Immo, well I’m interested in both. But I also understand how Microsoft works enough to know that (1) is much easier than (2). :P

So ultimately, I think both would be great, but for now, (1) is a good first step and a minimal requirement for us to use it in ReactiveUI etc.

So while I’d love to see these libraries be open source, I think a minimal next step would be to remove the platform limitation on the compiled library and all future libraries.

And not just to make us long haired (but soon to have a haircut) open source hippies happy, but to make us enterprise developers happy. To make us cross-platform mobile developers happy.