Microsoft has released a test version of its next-generation file system, WinFS, well ahead of schedule.

The software giant made the first beta of the new file system available to Microsoft Developer Network subscribers, who had not expected to see it until next year.

WinFS will not be a part of the next version of Windows, Windows Vista, when it ships at the end of next year, but will be available to the operating system as an add-on release sometime in 2007, said Quentin Clark, director of program management for WinFS at Microsoft.

The technology originally was scheduled to be part of Windows Vista but Microsoft cancelled that plan in August 2004. WinFS promises to make it easier for users to search and organise their files in Windows.

The beta includes a set of APIs and schemas that allow developers to start working with the new file system and get accustomed to the new data model, Clark said.

Microsoft is putting a lot of thought and care into WinFS because it is the file system that will drive Windows for a whole new generation of users. "As a file system technology, it’s important we get it right," Clark said.

Microsoft also will ask for developer feedback on the WinFS beta at its Professional Developers Conference next month. Microsoft will not make another beta release available this year, but expects there will be several more test versions of WinFS released between the initial beta and the final release of the file system.