Microsoft is back-porting its WinFS file-system technology to Windows XP, the same way that it is doing with its Windows presentation and communications subsystems, according to company officials.

The acknowledgement is significant, given that Microsoft has been reticent to offer any details on WinFS since the company decided in August to cut the WinFS information storage and retrieval feature from both the client and server versions of Longhorn.

Longhorn client is set to ship in 2006; Longhorn server in 2007, according to Microsoft.

Company officials have declined repeatedly to project when or how Microsoft would deliver WinFS to developers and customers. Microsoft's silence had led some industry watchers to speculate that WinFS would be relegated to the fate of "Cairo," the object file system that Microsoft touted throughout the 1990s but never managed to deliver.

A year ago, WinFS was slated to be one of the four main pillars of Longhorn. The other three, which are still set to be part of the next-gen Windows release, are the "Avalon" presentation subsystem; the "Indigo" communications subsystem; and the "Fundamentals" technologies that will improve Windows performance, security and reliability.

Microsoft decided to back-port both Avalon and Indigo to older versions of Windows — Windows XP and Windows Server 2003 — in order to maintain backward compatibility and help seed the application-development market, officials said. But it made no such promises for WinFS, which resulted in many developer, customer and industry-watcher questions about WinFS' fate.

WinFS isn't dead, Tom Rizzo, Microsoft's director of product management for SQL Server, recently told Microsoft Watch. In fact, Microsoft is planning to provide an update on the technology at this year's Professional Developers Conference (PDC) in September, he said.

Rizzo said that Microsoft is busily back-porting the WinFS file-system technology to Windows XP.

It's unclear if Microsoft also is porting WinFS to Windows Server 2003, but such a move would be likely, given that the Redmond software vendor is doing so with Avalon and Indigo.

The end result? Nearly all of the "original" Longhorn technologies are going to be made available for Windows XP and Windows Server 2003. There will still be some technologies unique to Longhorn, namely, the "Fundamentals." But will that be enough to convince users to upgrade?

Back-porting WinFS to Windows XP "could send a signal to customers that there's really no need to upgrade," said Robert McLaws, president and chief software architect with Interscape Technologies, the company behind the LonghornBlogs.com Web site. "Microsoft needs to be really solid about explaining their intentions" in order to keep customers from balking, he added.

But such a move is necessary, if Microsoft is serious about WinFS working in end-to-end scenarios, said Michael Cherry, Senior Analyst with the Kirkland, Wash., research firm Directions on Microsoft.

"For a file system to work it has to work in a lot of places," Cherry said. "FAT (File Allocation Table) still lives because it works on so many devices. So if Microsoft wants WinFS to take off and be useful and adopted, then it has to be widely available—work everywhere I want to work with my files (my information)."

(This is an updated version of an article which appeared in the February 24, 2005, issue of the Microsoft Watch newsletter. Want to see what other Microsoft news nuggets you might have missed? Sign up today for a free two-week trial subscription to Microsoft Watch.)