Microsoft Computing: The Windows "Longhorn" Operating System

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This month, I'll present some background and recent information about the latest and greatest version of the Windows desktop operating system: the "Windows Client Operating System," or "Longhorn."

What Is Longhorn?

Longhorn is a code name for a Windows operating system development project at Microsoft. Some of us remember when the System/38 was being reengineered by IBM under the project code name Silverlake. Whole companies adopted the word "Silverlake" into their names in some way, like "Silverlake Integration" or "Reflection Technologies." Silver Lake is a body of water in Rochester, Minnesota, and is a favorite of mostly geese. Likewise, Longhorn is the name of a bar and grill in British Columbia that lies between Whistler and Blackcomb mountains and is a favorite of mostly skiers.

Microsoft refers to Longhorn as the "Windows Client Operating System" and says Longhorn will deliver major improvements in user productivity, important new capabilities for software developers, and significant advancements in security, deployment, and reliability.

In an announcement last summer, Bill Gates said "Getting Longhorn to customers in 2006 will provide important advances in performance, security, and reliability and will help accelerate the creation of exciting new applications by developers across the industry." Yeah, well, that's pretty vague.

The "Three Pillars" of Longhorn

Longhorn was conceived originally with three primary enhancements over previous Windows versions, called the "three pillars" of Longhorn:

  • WinFS--An integrated relational database system
  • Avalon--A new presentation subsystem
  • Indigo--A new communication subsystem

WinFS is centered on a notion that will be familiar to most iSeries professionals: that of a database integrated with the operating system--not like MS Access or even Oracle, which are placed on top of the operating system and run in user space, but a real object-oriented, relational DB that is built into the OS kernel. Like the iSeries and its ancestors, Windows applications will be able to work with data files, indexes, constraints, security, etc. as part of the operating system itself rather than as an add-on database package. Further, the WinFS database will be capable of tracking XML metadata and tags about the objects it holds. The operating system will be aware of a file's record layout, index(es) to be updated after a write/update, text description, owner, authorized users, etc.

The WinFS has now been separated from the rest of the Longhorn release and will go to beta in 2006 with a formal release expected in 2007.

Avalon is a "unified presentation subsystem" made up of a new display engine and a managed-code framework. Avalon is intended to create a standard way for Windows to create, display, and administer documents, media, and user interfaces.

"Indigo is a new approach to building and running connected systems built from the ground up around a Web services-oriented architecture. The advanced Web services support in Indigo will enable more secure, reliable and transacted messaging and greater interoperability," according to a Microsoft press release.

Longhorn also includes WinFX, a replacement for the familiar Win32 API. WinFX is a "managed" API, meaning its execution is controlled by the .NET Framework Common Language Runtime.

The Two Windows Product Lines

From the early 1990s until fairly recently, Windows has taken two distinct product paths: one primarily for home and standalone use (Windows 95/98/Me) and another for networked business applications (Windows NT). Microsoft expected its more-advanced OS (NT 3.1) to replace Windows 3.1, but the new technology's 32-bit platform was not widely accepted by users. At the time, 32-bit operating systems required more hardware resources and there weren't any 32-bit applications to run anyway. So Microsoft developed a 32-bit-like version of Windows 3.1 and called it Windows 95, but it was still built on top of DOS. Continued user resistance to NT caused Microsoft to then develop Windows 98 and after that Windows Me, while claiming each to be the last of the 16-bit operating systems you'd see from them.

At the end of the 1990s, Microsoft was developing the next version of NT called NT 5.0. In a marketing masterstroke, the name was changed to Windows 2000 to provide a common migration path for both NT and 95/98 platforms. Then, from Windows 2000 came Windows XP and Windows Server 2003.

Since Windows 2000, Windows Server 2003, and XP are really NT 5.0, they take advantage of many of the superior features of NT:

  • A true 32-bit multiprogramming system with individually protected processes
  • A private 32-bit virtual address space for each process
  • An operating system that runs in kernel supervisor mode, and user processes that run in user mode
  • Processes that can have one or more threads that are visible to and scheduled by the operating system
  • Department of Defense C2-level security
  • Support for multiple processors running up to 32 CPUs

The fact that XP is really Microsoft NT is apparent in several places. The operating system kernel executable is called ntoskrnl.exe, for example.

A Built-In Problem for Microsoft Marketing

Some analysts speculate that Windows XP is where the two Microsoft product paths have crossed, creating complacency among Windows users. Windows 2000 and XP users now enjoy the benefits of the more stable and capable underpinnings of NT while retaining the familiar look and feel of traditional desktop Windows systems. Indeed, Microsoft estimates that less than 25% of XP users have installed Service Pack 2, indicating a lack of motivation to adopt new features (like the .NET framework).

Coupled with this, Microsoft has had difficulty keeping Longhorn on schedule and has made some modifications in the direction it will eventually take. One of the original three pillars of Longhorn, the WinFS file system, has been removed from the announcement and is said to be coming in 2007. More importantly, it could be that Longhorn will not be rolled out as an autonomous operating system. Compromises and delays may force Microsoft to break the rest of Longhorn into parts and integrate Indigo and Avalon into Windows XP. Most of the enhancements are of interest only to developers anyway, and gone are the days when the Rolling Stones sang "Start me up..." for the exciting new Windows 95 rollout. 3D graphics probably won't spruce up Accounts Payable much, either.

Microsoft has announced that the "Windows WinFX developer platform in Longhorn [is] available for Windows XP and Windows Server 2003," so at this time it is unclear what a strictly Longhorn feature will be.

Another unfortunate twist of irony lies in the endless security enhancements continually pouring forth from Microsoft for Microsoft products. Since the "Evil Empire" draws so much fire from those who would cause them harm, Microsoft must simultaneously promote its security measures while wincing at their necessity.

Longhorn in the Long Run

The latest news regarding Longhorn suggests Microsoft will add support for the WinFS database system to Windows XP. Microsoft announced last summer that it would add support for the Avalon graphics system and the Indigo communications subsystem to Windows XP and Windows Server 2003. Support for the new technologies in XP will greatly broaden the market base for applications created under them because initial plans were that applications created under Longhorn would run only on the Longhorn OS. No word yet as to whether WinFS will run under Windows Server 2003.

Even with the primary Longhorn features supported by XP, Microsoft has said the next Windows release will still be worth the upgrade because of the beefed-up security capabilities, improved stability, and other basics of the OS. Others aren't so sure. Many industry watchers believe Longhorn will be a tough sell for Microsoft. Applications developed for the new Longhorn technologies will run on existing XP or Windows Server 2003 systems, and there isn't enough to compel decision-makers to go through a technology transition. One analyst believes that computers and their operating systems have become like television sets in that users will not discard their current system until it no longer turns on.

A first beta release of Longhorn is supposed to be available by the end of June, and Microsoft is expected to hand out a preview release at the Microsoft Windows Hardware Engineering Conference (WinHEC) late next month.

For more information about Longhorn, see the MSDN Longhorn site.

Chris Peters has 26 years of experience in the IBM midrange and PC platforms. Chris is president of Evergreen Interactive Systems, a software development firm and creators of the iSeries Report Downloader. Chris is the author of The OS/400 and Microsoft Office 2000 Integration Handbook, The AS/400 TCP/IP Handbook, AS/400 Client/Server Programming with Visual Basic, and Peer Networking on the AS/400 (MC Press). He is also a nationally recognized seminar instructor. Chris can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..