Microsoft revealed quite a lot of detail about "Windows 8" and its programming model at the //build/ conference in September 2011. The result is a lot of excitement, and a lot of fear and worry, on the part of Microsoft developers and customers.
From what I've seen so far, in reading tweets and other online discussions, is that people's fear and worry are misplaced. Not necessarily unwarranted, but misplaced.
There's a lot of worry that ".NET has no future" or "Silverlight has no future". These worries are, in my view, misplaced.
But the important thing to understand is that WinRT is fully accessible from .NET. The model is quite similar to Silverlight for Windows Phone. You write a program using C# or VB, and that program runs within the CLR, and has access to a set of base class libraries (BCL) just like a .NET, Silverlight, or WP7 app today. Your program also has access to a large new namespace where you have access to all the WinRT types.
The BCL available to your Metro/WinRT app is restricted to things that are "safe" for a Metro app to use, and the BCL features don't duplicate what's provided by the WinRT objects. This means that some of your existing .NET code won't just compile in WinRT, because you might be using some .NET BCL features that are now found in WinRT, or that aren't deemed "safe" for a Metro app.
That is exactly like Silverlight and WP7 apps. The BCL features available in Silverlight or WP7 are also restricted to disallow things that aren't safe, or that make no sense in those environments.
In fact, from what I've seen so far, it looks like the WinRT BCL features are more comparable to Silverlight than anything else. So I strongly suspect that Silverlight apps will migrate to WinRT far more easily than any other type of app.
None of this gives me any real worry or concern. Yes, if you are a Windows Forms developer, and very possibly if you are a WPF developer, you'll have some real effort to migrate to WinRT, but it isn't like you have to learn everything new from scratch like we did moving from VB/COM to .NET. And if you are a Silverlight developer you'll probably have a pretty easy time, but there'll still be some real effort to migrate to WinRT.
If nothing else, we all need to go learn the WinRT API, which Microsoft said was around 1800 types.
So what should you worry about? In my view, the big thing about Win8 and Metro style apps is that these apps have a different lifetime and a different user experience model. The last time we underwent such a dramatic change in the way Windows apps worked was when we moved from Windows 3.1 (or Windows for Workgroups) to Windows 95.
To bring this home, let me share a story. When .NET was first coming out I was quite excited, and I was putting a lot of time into learning .NET. As a developer my world was turned upside down and I had to learn a whole new platform and tools and langauge - awesome!! :)
I was having a conversation with my mother, and she could tell I was having fun. She asked "so when will I see some of this new .NET on my computer?"
How do you answer that? Windows Forms, as different as it was from VB6, created apps that looked exactly the same. My mother saw exactly zero difference as a result of our massive move from VB/COM to .NET.
Kind of sad when you think about it. We learned a whole new programming platform so we could build apps that users couldn't distinguish from what we'd been doing before.
Windows 8 and Metro are the inverse. We don't really need to learn any new major platform or tools or languages. From a developer perspective this is exciting, but evolutionary. But from a user perspective everything is changing. When I next talk to my mother about how excited I am, I can tell her (actually I can show her thanks to the Samsung tablet - thank you Microsoft!) that she'll see new applications that are easier to learn, understand, and use.
This is wonderful!!
But from our perspective as developers, we are going to have to rethink and relearn how apps are designed at the user experience and user workflow level. And we are going to have to learn how to live within the new application lifecycle model where apps can suspend and then either resume or be silently terminated.
Instead of spending a lot of time angsting over whether the WinRT CLR or BCL is exactly like .NET/Silverlight/WP7, we should be angsting over the major impact of the application lifecycle and Metro style UX and Metro style navigation within each application.
OK, I don't honestly think we should have angst over that either. I think this is exciting, and challenging. If I wanted to live in a stable (stagnant?) world where I didn't need to think through such things, well, I think I'd be an accountant or something…
Yes, this will take some effort and some deep thinking. And it will absolutely impact how we build software over the next many years.
And this brings me to the question of timing. When should we care about Metro and WinRT? Here's a potential timeline, that I suspect is quite realistic based on watching Windows releases since 1990.
Win8 will probably RTM in time for hardware vendors to create, package, and deliver all sorts of machines for the 2012 holiday season. So probably somewhere between July and October 2012.
For consumer apps this means you might care about Win8 now, because you might want to make sure your cool app is in the Win8 online store for the 2012 holiday season.
For business apps the timing is quite different. Corporations roll out a new OS much later than consumers get it through retailers. As an example, Windows 7 has now been out for about three years, but most corporations still use Windows XP!!! I have no hard numbers, but I suspect Win7 is deployed in maybe 25% of corporations - after being available for three years.
That is pretty typical.
So for business apps, we can look at doing a reasonable amount of Win8 Metro development around 2015.
Yes, some of us will be lucky enough to work for "type A" companies that jump on new things as they come out, and we'll get to build Metro apps starting in late 2012.
Most of us work for "type B" companies, and they'll roll out a new OS after SP1 has been deployed by the "type A" companies - these are the companies that will deploy Win8 after has been out for 2-4 years.
Some unfortunate souls work for "type C" companies, and they'll roll out Win8 when Win7 loses support (so around 2018?). I used to work for a "type C" company, and that's a hard place to find yourself as a developer. Yet those companies do exist even today.
What does this all mean? It means that for a typical corporate or business developer, we have around 4 years from today before we're building WinRT apps.
The logical question to ask then (and you really should ask this question), is what do we do for the next 4 years??? How do we build software between now and when we get to use Metro/WinRT?
Obviously the concern is that if you build an app starting today, how do you protect that investment so you don't have to completely rewrite the app in 4 years?
I don't yet know the solid answer. We just don't have enough deep information yet. That'll change though, because we now have access to early Win8 builds and early tooling.
What I suspect is that the best way to mitigate risk will be to build apps today using Silverlight and the Silverlight navigation model (because that's also the model used in WinRT).
The BCL features available to a Silverlight app are closer to WinRT than full .NET is today, so the odds of using BCL features that won't be available to a Metro app is reduced.
Also, thinking through the user experience and user workflow from a Silverlight navigation perspective will get your overall application experience closer to what you'd do in a Metro style app - at least when compared to any workflow you'd have in Windows Forms. Certainly you can use WPF and also create a Silverlight-style navigation model, and that'd also be good.
Clearly any app that uses multiple windows or modal dialogs (or really any dialogs) will not migrate to Metro without some major rework.
The one remaining concern is the new run/suspend/resume/terminate application model. Even Silverlight doesn't use that model today - except on WP7. I think some thought needs to go into application design today to enable support for suspend in the future. I don't have a great answer right at the moment, but I know that I'll be thinking about it, because this is important to easing migrations in the future.
It is true that whatever XAML you use today won't move to WinRT unchanged. Well, I can't say that with certainty, but the reality is that WinRT exposes several powerful UI controls we don't have today. And any Metro style app will need to use those WinRT controls to fit seamlessly into the Win8 world.
My guess is that some of the third-party component vendors are well on their way to replicating the WinRT controls for Silverlight and WPF today. I surely hope so anyway. And that's probably going to be the best way to minimize the XAML migration. If we have access to controls today that are very similar to the WinRT controls of the future, then we can more easily streamline the eventual migration.
In summary, Windows 8, WinRT, and Metro are a big deal. But not in the way most people seem to think. The .NET/C#/CLR/BCL story is evolutionary and just isn't that big a deal. It is the user experience and application lifecycle story that will require the most thought and effort as we build software over the next several years.
Personally I'm thrilled! These are good challenges, and I very much look forward to building .NET applications that deeply integrate with Windows 8. Applications that I can point to and proudly say "I built that".
Update: here are a couple related blog posts from fellow Microsoft RDs:
and a good post from Doug Seven:
and from fellow Magenic experts: