Exploring the Windows App SDK

The Windows App SDK has currently reached version 1.0, and it includes the following features:

• WinUI 3
• Text rendering
• Resource management
• App life cycle
• Power state notifications
• Windowing
• Push notifications (preview)

The second section of this book will be focused on WinUI 3 and will guide you toward a modernization journey, with the goal of evolving your application from your existing UI framework (Windows Forms, WPF, or UWP) to embrace the latest innovation in Fluent Design.

This feature of the Windows App SDK is currently supported only by new apps that target WinUI 3. This means that this modernization journey will help you to reuse most of your existing code and libraries (thanks to the .NET runtime), but you won't be able to gradually move the UI of your Windows Forms or WPF application. You will have to use one of the new Visual Studio templates to create a new .NET application based on WinUI. Microsoft is working to bring a technology called XAML Islands to WinUI 3, which will instead enable developers to gradually migrate the UI of their applications by mixing controls from WinUI with controls from the existing UI frameworks (Windows Forms and WPF).

The third section, instead, will be focused on the developer platform – you will learn how to integrate the other features offered by the Windows App SDK, plus many other new APIs (such as geolocation and machine learning), which, previously, were available only to UWP applications. These features, unlike WinUI 3.0, can be easily integrated into existing desktop applications built with WPF and Windows Forms, as long as they have been migrated to at least .NET 5.

The Windows App SDK is distributed in three different channels:

• Stable: The releases distributed through this channel are supported in production environments. They include the latest stable and tested bits.
• Preview: The releases distributed through this channel include preview features that will be added in the next stable release. Being a preview, they aren't supported in production scenarios, since there might be breaking changes when the stable version gets released.
• Experimental: The releases distributed through this channel include experimental features, which might be discarded or completely changed in the next stable release. They aren't supported in production environments, since the included features might not even see the light.

All the features described in this book are included in the stable channel, except for push notifications, which are still in preview.

With an understanding of the Windows App SDK, our next step is to learn how to choose between an unpackaged and packaged deployment model. We will do that in the next section.