Microsoft's Jon Udell talks to former WinFS general manager Quentin Clark about the company's aborted plans to enhance the Windows file system with database technologies. What happened?

WinFS was about a lot of things. In part it was about trying to create something for the Windows platform and ecosystem around shared data between applications. Let's set that aside, because that part's not shipping.

Now the notion of having that shared data platform as part of Windows isn't something we're delivering on this turn of the crank. We may choose to do that sometime in the future, based on the technology we're finishing up here, in SQL, but it's not on the immediate roadmap.

You can look at work that we're doing now for SQL Server 2008, or ADO.NET, or VS 2008 SP1, and trace its lineage back to WinFS.

People would often ask me if WinFS was a file system, and I'd struggle with the answer to that, because, well, you know, from a certain standpoint the answer is yes. The stuff I saw in the shell, was it in the WinFS filesystem? Well, OK. But there are no streams inside the database. So from a user perspective, those files were "in" the filesystem. But from an API perspective it was more nuanced than that. I could still use the Win32 APIs, get some file, open it, and from that point forward the semantics were exactly like NTFS. Because it was NTFS at that point.

There is a lot more there. Fascinating read.