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The Road to Windows 8 Development Success

Key Tenets and Skills

Did you spend the weekend getting to know your Surface – like many of those who lined up at Microsoft Stores across the country?

And now you’re considering getting your own application into the Windows Store, but not sure where to begin?

Well, we all started somewhere, and although I’m far from laying claim to a Windows 8 app with thousands of downloads, over the past few months of working with developers as well as on my own, I’ve settled on my own shortlist of things to know about Windows 8 development that are I feel are keys to future success.

Read the store certification requirements, then read them again.

For your application to be in the Windows Store, it must pass certification which comprises a set of security, technical, and content compliance tests. Simply leaving a debug statement in your code or forgetting to provide a privacy policy for your application can result in rejection. Before you submit your app you’ll definitely want to make sure it passes the Windows Application Certification Kit on your own device. Take a look as well at Resolving certification errors to avoid common issues and the resulting delay in getting your application on the market.

User experience matters.

Windows Store applications are different. They look different and act differently from what many of us have previously built on the Windows platform – whether it be Windows Forms, WPF, Silverlight or ASP.NET. It’s not just a matter of translating user interface elements or applying a new theme or skin. Successful Windows 8 applications will embrace the modern Windows application design, which have been influenced by movements like the Swiss Style and Bauhaus. Take time to embrace the Windows 8 design principles, and eschew skeumorphism!.

When it comes to crafting that user experience, there are many different avenues available: XAML (with Visual Basic, C#, and C++), DirectX with C++, and CSS with HTML5 and JavaScript. The more adept you are with those rendering technologies, the more compelling your app will be. In that journey, you’ll likely find yourself gravitating more and more to the incredible functionality of Blend for Visual Studio.

For building games, even more options abound, including multiple JavaScript libraries like ImpactJS and EaselJS and offerings like GameSalad and Construct 2. Full-featured game engines like Unreal Engine 3 and Unity have also announced support for Windows 8.

Embrace the MVVM pattern.

Windows 8 applications typically consist of just a few (or perhaps even just one) page, with controls and data-binding governing much of the experience. The Model-View-ViewModel design pattern (which is a close cousin of Presentation Model, Model-View-Presenter and Model-View-Controller) has quickly become the de facto model for XAML based application development, whether it be Silverlight, WPF, or Windows 8. For HTML5/JS applications, data-binding is also a key facet; however, since two-way binding is not explicitly supported, there can be a bit more work involved when using MVVM.

You’ll find there’s even a DefaultViewModel property for many of the XAML-based Windows 8 project templates to steer you toward this goal.  There are also some excellent blog posts from various authors on the topic, and the MVVM Light Toolkit (from Laurent Bugnion) is a common starting point.

Windows Store applications are mobile applications.

If you’ve built applications for Windows Phone or even iOS or Android, you will be familiar with a focus on providing a consistent, responsive user experience. To guarantee that level of experience regardless of the what is currently running on that device, applications are necessarily constrained. They run within a sandbox with limited access outside of that sandbox (unless authorized by the user), and they have a very distinct lifecycle controlled by the user and the operating system more so than by the developer.

Successful applications built for Windows 8 will be mindful of battery life, provide both a connected and a disconnected experience, work well on low-power devices, and mold the experience to the characteristics of the device on which they are executing thus becoming authentically digital.

Understand the application lifecycle.

Every Windows 8 Store application is bound by the same lifecycle, and it’s incumbent on the developer to understand when state transitions occur and what actions should be taken as a result.

For instance, an application can be activated by clicking on its live tile of course, but it may also be activated through a search or by another application via protocol activation. And as soon that other application is brought into view, the current application is suspended. It’s then up to the developer to save any application state, since a suspended application could be completely terminated by the operating system – with no further notification - should there be memory or battery life pressure.

State diagram showing transitions between app execution states

Asynchrony is the norm.

Windows 8 applications are often characterized in marketing-speak as fast and fluid. The consistency of performance in reaction to user input is a key part of the experience and enforced by strict timing requirements. For instance, applications much launch within five seconds or less and must suspend in two seconds or less.

In fact, any operation that takes more than 200 ms is a prime candidate for an asynchronous implementation, one that does not require the UI to stop and wait for it to complete. This is baked into Windows RT as well since most file and network operations are available only as asynchronous methods.

Luckily asynchronous processing has become that much easier in .NET 4.5, and Visual Basic and C# developers can leverage the async/await pattern, allowing them to code in a synchronous style but with asynchronous methods. JavaScript developers can use promises that similarly abstract the complexities of asynchronous programming. And if you’re a C++ developer, then you’ll be using the task class that’s part of the Concurrency Runtime,

Notifications can be a key application differentiator.

Notifications are a fantastic feature of the Windows 8 platform, one that can take your application from meh to wow. A built-in notification engine can serve up tile, toast, and badge updates to your application even when the application isn’t running - thus expanding its presence and impact in the eyes of your users.

Live tile updatesTile notifications provide the glance-and-go experience that differentiates the Windows 8 Start Screen. Live tiles are the only persistent visual presence of your application on the user’s device, and they are “live” solely because of notifications, providing updates to your application and enticing the user to run your app again and again.

Toast notifications are more personalized and immediate, informing the user of something of specific interest that’s actionable right at that time. Used appropriately they can provide a compelling, just-in-time experience and be part of an application the user just can’t do with out.

Lastly, badges are essentially an extension of the tile, providing a quick indication of the state of an application, like whether a video has been paused or how many unread e-mails are in your in-box.

Leverage contracts and extensions to broaden your application’s presence.

The sandbox model of a Windows Store application at first seems incredibly constraining – you can’t write to the file system, can’t read from the registry, can’t even detect what version of Windows is currently running! If you step back and view things from an end-user perspective though, you’ll realize that many of those capabilities serve the developer and not the user. In Windows 8 the user is in charge, and a consistent experience is paramount.

In some ways it’s liberating and democratizing for developers, there are defined rules – contracts, if you will – that every application has access to and no application can circumvent.

  • Want to save a file to C:\ directly? Your application can, but the user must approve that action through the file picker.
  • Want to have your application automatically handle a certain type of file? You can, but via file activation, and even then the user gets to pick which application she wants to response to that request (from among installed applications than can handle that file type).
  • Want to search across data managed by other applications? You can - via the search contract.

It’s through these contracts and extensions that your users’ experience can extend beyond the boundaries of your own application and your application can reach new users through discovery mechanisms built-in to the Windows 8 runtime.

The Cloud is a unifier.

Does anyone have only one internet connected device in this day and age? We have smartphones, laptops, desktops, game consoles, etc., many of which run similar or companion applications, and increasingly we expect our experiences to transcend the device. We watch a movie on our slate or phone during the commute on the train and expect to finish that movie at home on our Xbox. We increasingly rely on apps like OneNote and Evernote to make our to-do list available wherever we happen to be at the time.

Underlying the connected experiences is the cloud, and within Windows 8 it’s not a bolted-on experience. SkyDrive is a first class citizen, your social media presence on Twitter, Facebook, LinkedIn, Google are linked in the People app, and developers can make use of roaming storage which automatically handles the synchronization of application data across Windows 8 devices linked to a given user’s Microsoft account.

Windows Azure - try free for 90 daysStepping it up a notch, Windows 8 applications can easily tie into Windows Azure Mobile Services for common application needs like simple structured data storage, authentication across identity providers like Facebook and Twitter, and to provide the plumbing for push notifications. Of course you don’t have to stop there, Windows Azure has numerous other services that you can easily tap into to increase the impact, reach, and agility of your application.

Your profits are in your hands.

Having your application in the Windows Store is a tremendous opportunity, with over 670 millions upgradeable licenses of Windows 7 in the wild now and an estimated 300 million units of Windows 8 shipping in 2013, so take some time to decide how to monetize your application, as there are several options you can use alone or in combination.

  • You can simply charge for your application (anywhere from $1.49 to $999.99), where each download is a purchase and you retain 70% of the proceeds (or 80% once you’ve reached the $25,000 mark). Optionally, you can opt to enable a time-limited or feature-limited trial as part of your application, which can significantly increase your purchase rate over an application without such an option.
  • You might decide not to charge for the app at all and make your money from ads presented within your application via the Microsoft Advertising SDK or a third-party ad provider. By the way, according to a 2011 Gartner report, mobile advertising revenue is slated to reach $20.6 billion 2015, up from $3.3 billion in 2011.
  • Increasingly, applications are turning to in-app purchases as a primary monetization technique either using the built-in Windows.ApplicationModel.Store namespace or a third-party commerce provider. As food for thought, in July 2011 Distimo noted that although only 4% of all iPhone applications leveraged in-app purchases, those purchases accounted for 72% of all application revenue, a 150% increase over the prior year. That same report also showed that free downloads of applications exceeded those of paid applications by a factor of five.

Before settling on your approach, do take time to review other apps in your category and the monetization trends for those applications. Different types of applications engender different expectations on the part of end users. For example, statistics from the Windows Phone store indicate that consumers are more likely to pay for games than for any other category of applications, by a factor of six.

In conclusion, I wish you good luck on your Windows 8 development journey, and I welcome your thoughts, stories, and feedback!

More Stories By Jim O'Neil

Jim is a Technology Evangelist for Microsoft who covers the Northeast District, namely, New England and upstate New York. He is focused on engaging with the development community in the area through user groups, code camps, BarCamps, Microsoft-sponsored events, etc., and just in general serve as ambassador for Microsoft. Since 2009, Jim has been focusing on software development scenarios using cloud computing and Windows Azure. You can follow Jim on Twitter at @jimoneil