By Michael Cherry [bio]
Posted: Nov. 17, 2003

• Illustration: Basic Longhorn Architecture

The following is the full text of an article published by Directions on Microsoft, an independent research firm focused exclusively on Microsoft strategy & technology. Each month we make one or more key articles available to non-subscribers.

The next release of Windows, code-named Longhorn, will fundamentally change the way that developers create applications for the first time since the introduction of Windows NT and the Win32 API. The changes, demonstrated at the Professional Developers Conference (PDC) in Nov. 2003, involve the deep integration of the .NET Framework into Windows, which Microsoft hopes will spawn a new generation of applications that will only be available on Windows Longhorn, compelling users to upgrade.

Why an Early Heads-Up?

With Longhorn, Microsoft is introducing new subsystems to improve graphics (code-named Avalon), to support Web services and other types of communications between applications (code-named Indigo), and for accessing data stored in the file system (code-named WinFS). Developers will reach these subsystems through a new set of APIs, called WinFX, that take the .NET Framework, extend it significantly, and move it into the OS. (See "WinFX: The .NET Framework Takes Center Stage" in this issue.)

These subsystems and associated class libraries are being added to the OS and augment rather than replace older subsystems such as the Graphics Device Interface (GDI) and "User," the two subsystems that currently control how graphics are drawn and how windows and controls, such as buttons, are created and managed. By offering new alternatives rather than completely replacing the existing subsystems and APIs, Longhorn will be able to run "legacy" Win32 applications. (For a graphical overview of these new systems and how they fit alongside the existing Windows architecture, see the illustration "Basic Longhorn Architecture".)

Microsoft is encouraging developers to look at the WinFX API and the Avalon, Indigo, and WinFS subsystems now, hoping that the new features and capabilities Microsoft is adding to Longhorn will unleash developers' creativity, allowing them both to develop new applications and to improve existing ones with features that would be difficult or impossible to develop with the existing Win32 APIs. During the development of Longhorn, Microsoft will continue to promote it to developers so that when Longhorn finally ships there will be applications that will drive users to upgrade to the new OS.

Microsoft also acknowledges that it is too soon to extrapolate from the preview release how the final user interface and shell (code-named Aero, which is an element of Avalon) will look when the product is released. Therefore, the implementation of the end-user UI included with the PDC Longhorn preview should be considered, at best, a prototype.

New Subsystems and APIs

Three major Longhorn subsystems were described in detail at the PDC. They include new systems to control graphics display, interapplication communications, and the file system. They are known for now by the following code names:

Avalon provides a new vector-based graphics engine and class libraries for drawing UI elements, such as windows, forms, and controls.

Avalon provides an alternative to the graphic services and APIs provided by GDI and User, and brings additional capabilities previously only available via DirectX—the low-level API used by game developers to create sophisticated graphics. By incorporating the graphics capabilities of DirectX, such as transparency and rotation, and support for hardware graphics acceleration into the "mainstream" API, Avalon will make it possible for a broader range of developers to build sophisticated user interfaces or applications with advanced graphic elements, such as transparent windows.

Indigo provides an organized infrastructure for interapplication communication, such as secure and reliable messaging and transactions for Web services.

Developers can use Indigo to build applications that support an array of emerging Web services standards with far less code than would otherwise be required. Indigo also provides OS-based services such as those that are today provided by subsystems such as the Message Queuing service (MSMQ). These Indigo services and the associated common APIs integrated in the OS will ease development of service-based applications such as Web services, allowing developers to easily create applications that exchange data across networks with little or no user intervention.

WinFS stands for Windows "File System" or "Future Storage" and is a final key change to Windows. This subsystem and accompanying class libraries extend the existing NTFS file system by adding support for sophisticated data organization and retrieval. For example, WinFS will allow users to easily associate files with user-defined properties, such as the genre of music in a media file, which should make it easier to logically keep related files together and to locate the file again when the user wants it.

WinFS will provide an easier path than Win32 and existing input/output subsystems for users and applications to store, retrieve, back up, restore, synchronize, and replicate data stored in NTFS.

Long Road to Longhorn

The next significant Longhorn milestone will be the first beta, which is due in mid-2004.

Between now and that first beta, Microsoft will be looking for feedback from developers about how the proposed changes to Windows affect their development plans, and on any changes or additions Microsoft needs to make to the subsystems and APIs to ensure developers will write applications that exploit them.

Resources

For more information on the Web Services Architecture, see "Web Services Specifications Inch Forward," on page 26 of the Nov. 2003 Update.

For more information on Longhorn, see msdn.microsoft.com/pdc.

Roadmaps for Windows and other key Microsoft enterprise products can be found in the Directions on Microsoft "Enterprise Product Roadmap".