Over the weekend, Mary Jo Foley (Microsoft Watch) asked me, “What does it mean that something is IN WinFX, but may or may not be IN Longhorn?”

I have to admit that answering this question was more difficult than I wanted it to be. Folks at Microsoft use a lot of terms (like .NET and Avalon and Indigo) to mean different things depending on context – it’s a kind of developer shorthand that causes confusion with a lot of folks when it’s not Microsoft people talking to other Microsoft people.

For starters, WinFX is not a physical thing, but the specifications to a bunch of APIs – in fact, the specifications to every managed API (technically, they’re classes, but that’s another matter) that there is. So anything that exposes its features through WinFX is “in” WinFX, even if it doesn’t ship in a Windows box. (In this case, “in” means “exposed through.”)

By contrast, Avalon and Indigo (and WinFS) *are* physical things. They’re features of Windows “Longhorn.” On Longhorn, Avalon and Indigo are “just there” – that is, apps can just use them without thinking about it. On Windows XP and Windows Server 2003, we’ll be making what’s called a “redistributable package” that developers, IT admins, and end users can install on their computer at no additional cost. Basically, this is just like the .NET Framework today. Right now, we’re calling this redistributable the “Microsoft® Pre-Release Software Code Named ‘Avalon’ and ‘Indigo’ Beta1 RC.” 

As a side note, we (in this case, I) confused things with the name “.NET Framework.” The .NET Framework was both a THING (a piece of software you could go and download and install on Windows) and its programming interfaces. That worked fine until people added new namespaces for things like SQL Server and Office. Were those part of the .NET Framework? Well, they weren’t something that you downloaded in the .NET Framework redistributable, but those new classes became part of the .NET Framework namespaces.

Mary Jo is a sharp person, and the folks on Channel9 who are saying that she needs to be “spanked” are missing the fact that she’s asking questions that a huge number of customers are asking.