Microsoft's Project Reunion Preview v.0.5 which unify Win32 and UWP APIs, now available

At Build 2020, Microsoft announced Project Reunion, a new project to make app development easier for Windows 10 platform. Project Reunion unifies access to existing Win32 (legacy Windows API) and UWP (Universal Windows Platform) APIs and makes them available decoupled from the OS, via tools like NuGet. Apps built using Project Reunion components can work across all the Windows 10 versions and devices.

Yesterday Microsoft released Project Reunion preview v.0.5.

Benefits of Project Reunion for Windows app developers

Microsoft says Project Reunion offers the following benefits for Windows app developers

Unified API surface across desktop app platforms

Developers who want to create desktop Windows apps must choose between several app platforms and frameworks. Although each platform provides many features and APIs that can be used by apps that are built using other platforms, some features and APIs can only be used by specific platforms. Project Reunion will unify access to Windows APIs for all desktop Windows 10 apps. No matter which app model you choose, you will have access to the same set of Windows APIs that are available in Project Reunion.

Over time, Microsoft plans to make further investments in Project Reunion that remove more distinctions between the different app models. Project Reunion will include both WinRT APIs and native C APIs.

Consistent support across Windows 10 versions

As the Windows APIs continue to evolve with new OS versions, developers must use techniques such as version adaptive code to account for all the differences in versions to reach their application audience. This can add complexity to the code and the development experience.

Project Reunion APIs will work on Windows 10, version 1809, and all later versions of Windows 10. This means that as long as your customers are on Windows 10, version 1809, or any later version, you can use new Project Reunion APIs and features as soon as they are released, and without having to write version adaptive code.

Faster release cadence

New Windows APIs and features have typically been tied to OS releases that happen on a once or twice a year release cadence. Project Reunion will ship updates on a faster cadence, enabling you to get earlier and more rapid access to innovations in the Windows development platform as soon as they are created.

Limitations and known issues

• This release is not supported for apps that are used in production environments. Expect bugs, limitations, and other issues.
• This release can only be used in MSIX-packaged desktop apps (C#/.NET 5 or C++/Win32). It cannot be used in unpackaged desktop apps.
• The tools limitations for WinUI 3 also apply to any project that uses Project Reunion 0.5 Preview.

Learn how to get started from Microsoft’s blog post here.