Longhorn Promises Backward Compatibility

"Barring security issues," programs built to Win 32 specifications will also run in Longhorn, said Jim Allchin, group vice president of Microsoft, Redmond, Wash. Programs built atop the .Net Framework will also run in Longhorn, although they will not be able to take full advantage of its perks, Allchin said at the Microsoft Professional Developers Conference in Los Angeles.

Designated demo guys Don Box and Chris Anderson, Windows architects of Indigo and Avalon, respectively, built some quick applications on stage using the open-source Emacs realtime display editor. They even brought up Visicalc, the 20-year-old pioneer spreadsheet, in a resizable window.

Avalon is the presentation layer of the nascent operating system, and Indigo is the communications layer.

The talk of backward compatibility, always a bugaboo for new operating systems, surprised one longtime Microsoft partner who has been briefed on most Longhorn developments. "This is the first time I've heard them stress this. And it's important," he noted.

Of course, the state of the Longhorn client code, early bits of which were distributed at the conference, is very rough. Allchin cautioned attendees not to use it on production machines, to install only on high-end boxes and to keep it off the Internet. "We've never shared bits this early before," he said.

Another Microsoft insider concurred. "The performance is rotten; it's insanely slow. [But] the new WinFS file system is the big story, along with the APIs built around it," he said.

The promised WinFS file system, built atop database technology, will provide a unified store for all data types, regardless of where they reside on the user's system or server.

Along with the promises of backward compatibility, Allchin challenged the audience of developers to start moving down the Longhorn path for new projects and to utilize Longhorn's WinFX programming model, as it becomes available, to take advantage of glitzy planned features in the operating system.

Steps along that road will be the use of Whidbey, the next release of Visual Studio due next year, and the Longhorn SDK.

By all accounts this is a huge project. The "developer preview" of the client software was distributed at the show on Monday, and Allchin promised Beta 1 in the second half of 2004. He did not cite any dates for the Longhorn Server. Earlier this month, another senior Microsoft executive reiterated plans to ship the Longhorn client in 2005 and the server the following year.