Windows Vista is coming! The successor to Windows XP is expected to ship in 2006, and now that the Community Technology Preview betas are available, it's time to start working with the new operating system's APIs and structures. There's a lot of rich goodness in Windows Vista, particularly for developers. You'll find many reasons to begin migrating apps to the platform, as well as start thinking about new code that can leverage its cool new features, like the built-in workflow engine and RSS features.

If you haven't started working with Windows Vista yet, you might be feeling somewhat confused as to exactly what's new or interesting with the new operating system. Part of that confusion is due to the sheer number of new features, interfaces and frameworks in Windows Vista; we'll talk about them in a moment.

But another part of that confusion is due to the number of new names and terms, including a bunch of now-abandoned codenames, and the fact that Microsoft dribbled out many of the details piecemeal. For example, for the longest time everyone called the new operating system Longhorn, and even today, you'll hear folks use the term, and find key components called Avalon or Indigo in documentation and articles online. (The codename "Longhorn Server" is still widely used for the unnamed successor to Windows Server 2003.) It's time to deal with those codenames and round up the key new features, once and for all.

In this article, written for Windows developers who haven't yet started programming for Windows Vista, we'll look at some of the most important new infrastructure layers and APIs within the new operating system. We'll also match up the codenames with the official names. Our objective: Wipe out the confusion, and establish exactly what's in Longh... I mean, in Windows Vista that makes it so exciting.

WinFX: Managed Code Programming Model
The centerpiece of Windows Vista's new developer platform is WinFX, a new programming model that combines the power of the .NET Framework 2.0 with new technologies for building applications that have visually compelling user experiences, seamless communication across technology boundaries, and the ability to support a wide range of business processes.

Because WinFX is an evolution of the .NET Framework, the millions of developers who use .NET today can use the skills they already have to start building WinFX-based applications. So whether you're a developer using Microsoft Visual Basic, C++, C#, or any of the other languages supported on the .NET Framework, WinFX is suited to your needs.

WinFX isn't just for Windows Vista. Microsoft will be releasing versions of WinFX that can run on Windows XP and Windows Server 2003.

Windows Presentation Foundation, XAML and Aero
An important component of the WinFX API is the Windows Presentation Foundation, formerly codenamed "Avalon." WPF represents an entirely new graphics subsystem which eliminates the distinction between local applications and those running remotely or through a browser.

There are several exciting advances with WPF. One is that the interface language is a dialect of XML, called XAML—the Extensible Application Markup Language—which is used for describing and drawing application user interfaces. Another is that WPF is inherently extremely flexible, partially because it incorporates both 2D and 3D graphics primitives and widgets, and partially because it's vector-based. That means stunningly sharp fonts, smoother video playback, and a GUI that can scale and adapt to a variety of display devices.

Windows Vista will also contain a new 3D user interface called Aero, which is built on top of WPF and XAML. Check out some of the previews. Aero replaces the old Windows Explorer that we've all known since Windows 95 came out more than a decade ago.

Windows Communication Foundation: More than Web Services
Think about all the APIs that you use to communicate with the outside world, like ASP.NET, Web services, Microsoft Message Queue (MSMQ), COM+, and .NET Remoting. You know how much of a nuisance it is figuring out the syntax of each of those APIs—and in building applications that can seamlessly communicate with multiple data sources using multiple APIs? That problem is going away with the introduction of Windows Communication Foundation, another subset of WinFX. WCF, which had been codenamed Indigo, unifies all those APIs and more.

Applications written to use WCF have to go through just three steps to define and engage in communication: Know the address, bind to the service, and establish a contract. All of these are expressed using industry standard Web services protocols, and in many cases, you can initiate communications in just a few lines of code.

It doesn't matter if it's a Web service you're trying to talk to or a COM+ object, the WinFX runtime will sort out the details. For many developers, WCF is going to be a significant time-saver when it comes to building connected systems. (To get a good idea how it works, read Clemens Vasters' great article, "Introduction to Building Windows Communication Foundation Services.")

Windows Workflow Foundation: Wrestling with Processes
Windows Workflow Foundation (WF) provides a programming model, engine and tools for building workflow-enabled software. WF is one of the most innovative parts of Windows Vista. No other operating system has been ambitious enough to include a built-in workflow engine that can span any managed application (and thanks to Windows Communication Foundation, address nearly every protocol), and it's probably the part of Windows Vista that I'm most excited about.

WF lets developers define complex workflows that can encompass both applications and human interactions. These workflows can be combined to create "activities," and can be written using the XAML language mentioned earlier, or any managed language like Visual Basic or C#. Activities and workflows can also be generated programmatically. Message queuing, conditional branching, escalation, monitoring, reporting—it's all there, and will be part of the WinFX infrastructure. Workflows and activities might be limited to a single desktop or server, or span multiple machines on the LAN or on the Internet. With WF, business process workflow just part of the plumbing.

There's More—Lots More
WinFX, WF, WCF, WPF—those are just four of the biggest additions to Windows Vista. But they're not the only changes in this release. Three other items worth pointing out are:

• There's a new security and identity management infrastructure layer, called InfoCard. The operating system will also have embedded spyware technology, called Defender—that's the official name for the Windows AntiSpyware beta that many of us are running today.
• Microsoft has embedded RSS (Really Simple Syndication) capabilities into Windows Vista, and they can be used for not only subscribing to human-readable information feeds, but also for implementing sophisticated publish/subscribe data integration services.
• WinFS, a new relational file system, was supposed to be part of Windows Vista, but now looks to be delayed. However, when WinFS is ready, it'll offer a unified data model for all applications, encompassing both structured and unstructured information.

Whirlwind Tour
To emphasize my original point: There's a lot of goodness in Windows Vista, but also a lot of complexity. With luck, we've straightened out all the issues with the old codenames, like Longhorn, Avalon and Indigo, and clarified exactly what the different "foundations" are and what they do.

What's the next step? Download the Windows Vista community technology previews and WinFX runtime candidate betas, fire up Visual Studio, and dive deep. Because many of these technologies will be backward compatible to Windows XP and Windows Server 2003 through the WinFX download expected in late 2006, you don't have to worry about an installed base for your applications. The users are going to be there. It's time to start getting your new and migrated applications ready for them.