i'm all smiles today : sharing the source code for .NET 3.5 libraries

Viva transparency, openness!

Today we are announcing that release of source code for the .NET 3.5 Framework Libraries. As some of you may know, I'm an avid open and shared source fan ("Open Source at Microsoft", "Open Source Projects in the MS Ecosystem"), and this is a big step in the right direction for Microsoft.

Why are we doing this?

  • Primary reason : to enable deeper debugger integration.
  • Developers can better understand Microsoft's design patterns and our implementation methodologies. I think this can also help developers understand what is happening underneath the covers.
  • There are lot of benefits for developers, customers, partners, and Microsoft. when it comes transparency with source - it facilitates better communication and trust.

How can you view the source?

You can download it (location TBD) and view it using any editor. The ideal way to use it would be to use the source with Visual Studio 2008 (codename 'Orcas').

What libraries will be included?

Base Class Libraries (mscorlib.dll)

ASP.NET (System.Web.dll)

Windows Forms (System.Drawing.DLL & System. Windows.Forms.dll)

ADO.NET (System.Data.DLL)

XML (System.Xml.DLL)

WPF (System.Windows.DLL)

Why aren't you truly open sourcing this?

First, these are my opinions, not necessarily those of Microsoft's.

I think there are two fundamental aspects to open source software :

  1. community creation and participation of the (open source) project, and
  2. sharing of the project's source code.

With this effort, we are only really facilitating #2 (that sounded odd).

There's a lot we learn from the open source community. A few of us in the company who are OSS advocates have lent our thoughts, and I think overall, this "ship" is headed in the right direction (keep in mind, this is a BIG ship). And, we're taking small baby steps.

The .NET platform is a beautiful beast - it's an awesome development platform with vast adoption. We take pride in our development, our developer support and the reliability you get as a result of our efforts. So, today, we are trying to strike a balance between the investment we make in the software we build, and being more collaborative, open and transparent with our source code.

What license will this code be released under?

(Warning : I, like most humans out there, am no licensing expert, so I'm going to keep this really short)

We're releasing the source under the Microsoft Reference License (Ms-RL).


Visual Studio 2008's anticipated release is later this year/early next year.

What does downloading the source cost?


Huge credit goes to Scott Guthrie and Shawn Burke. They have detailed information about this news here and here.


PS : Now you know why Phil Haack is going over to work at Microsoft (on Shawn's team) ;)

Technorati Tags: shared source, oss, open source, microsoft, microsoft reference license, ms-rl, visual studio, visual studio 2008, orcas, scott guthrie, shawn burke