The three faces of Windows 8
Instead of looking at Windows 8 as a unified operating system running on two different sets of hardware -- along the lines of, say, Windows NT, which ran on several different platforms -- IT and developers should think of Windows 8 as having three distinct flavors, shown in Figure 2.
Desktop on Intel
Desktop on ARM
Figure 2: The three very different faces of Windows 8, from a corporate developer's perspective.
Based on the Developer Preview, it's very likely that Microsoft will maintain near-100 percent compatibility with Windows 7 apps, running on the Windows 8 Desktop with Intel/AMD hardware. All of the development tools IT uses with Windows 7, including Silverlight, should work with Windows 8, unchanged, as long as the target is the Windows 8 Desktop on Intel/AMD hardware.
But if you're aiming for the Desktop on ARM machines, it's a completely different can of worms. There's a reason why the tablets given away at the Build conference were Intel-based.
If you keep those three different scenarios in mind (Metro vs. Desktop on Intel vs. Desktop on ARM), Microsoft's official box chart, describing the highest-level interactions in Windows 8, makes some sense. (See Figure 3.)
Now you see the flip side of Steve Sinofsky's statement during last week's financial analyst Q&A session: "We've been very clear ... that the ARM product won't run any X86 applications. What we announced yesterday for the first time was that when you write a Metro-style application, all the tools are there to enable you in any of the languages that we support to automatically support ARM or X86."
Corporate developers' concerns about Metro
In reality, there are only three ways to write Metro applications:
- In C++, writing directly to the Metro Windows Runtime (WinRT) API. (There's a trick for making a native C++ project accessible to WinRT components, described in this Social MSDN thread.)
- In the pared-down .Net 4.5, using C# or VB. (Your program can't call any of the "disallowed" APIs.)