In a recently posted video on Channel 9, Microsoft’s Immo Landwerth and David Kean explain the reasoning behind making .NET Open Source.

In this video, Dan Hernandez talks to Immo Landwerth and David Kean from the .NET Framework team to explain the thinking that went into the decision to open source the .NET Framework as well as what it means for the future of .NET development.

Everything we did was slowed down by our desire to ship stable bits — Immo Landwerth

The primary driver seems to be the desire of Microsoft to be able to make changes to the .NET Framework in a more agile model.  In this model, changes to the .NET Framework will no longer be tied to Windows Releases.  Another key factor is the ability to have community input into the frameworks, a factor that has already begun to gather steam.  They claim to have already received more than 100 pull requests on their GitHub project including more than 40% of them from the community.

Managing the affects of an ever-changing environment will become the responsibility of the developer and can be managed as they choose to adopt versions of the .NET Framework to use.  One example of this is where a new overload was added to a library method that then broke another developer’s reflection code.

The video also goes on to describe via whiteboard how the new Core CLR and .NET Native will support development across platforms.