Windows as a universal app platform – Also iOS and Android apps to Windows

You don’t hear much about it lately, but not so long ago the app stats were flying around. Apple boasted with so many million apps for iOS and Google did so with its own superlatives about the number of Android apps. At Microsoft, however, it remained anxiously silent. The number of mobile and ‘Metro’ apps lagged well behind the competition, and it’s not the only, but important, reason that Windows Phone hasn’t had the consumer appeal that Microsoft hopes it will have. Microsoft wants to do something about that with the Universal Windows Platform.

The four bridges

To lure more apps to Windows 10, Microsoft is offering four bridges , as the company calls it. These toolkits should bridge the gap between Android, iOS, the web and the older Windows apps on the one hand and Windows 10 as a universal platform on the other.

Especially the ability to port Android and iOS apps to Windows is causing a stir. Those projects for Android and iOS are known as Project Astoria and Project Islandwood respectively. Microsoft is courting developers for those popular platforms by making it really easy to bring their apps to the Windows platform. If the company’s message is heard, the number of mobile apps for Windows could increase rapidly. You can then use the same, or at least very similar, apps on your Windows smartphone, as you know them from Android and iOS. That was different until now: even popular Android and iOS apps were sometimes still missing on Windows Phone.

Microsoft is trying to lure developers with the prospect of gaining a large new audience without much effort. The aim is to equip 1 billion devices with Windows 10 within two to three years. These are PCs, smartphones, tablets, consoles and other systems together. Now it is true that Universal Windows Apps must be able to run on all those devices, but in the case of the Android ports, that kite does not work.

Android and iOS

Android apps can only run on Windows 10 Mobile, thanks to an Android runtime layer in that OS. Developers should first see what part of the code works by having the .apk installer file analyzed, and then they may need to make changes.

Both Java and C++ Android apps can be encapsulated in Microsoft’s appx package, but that doesn’t make them “full” universal Windows apps. Microsoft uses interop and direct api-mapping to convert ‘common’ Google Play Services, but not all APIs that use the apk’s can be automatically transferred.

Users will see the interface elements of Windows 10 Mobile with Android apps on Windows, such as those for sharing content and selecting and cutting and pasting text. In addition, the apps integrate with the notification system of the OS and get a Live Tile. If the app has Google Maps integrated, it will be converted to Bing Maps and the same goes for other services, such as the advertising system and the in-app purchase option. The subsystem that runs the Android app can use hardware acceleration, DirectX, and Windows resource management , and performance should be similar to Android, Microsoft claims.

Bringing iOS apps to Windows is done in a totally different way. Microsoft makes it possible to import Xcode projects of apps written in Objective C into Visual Studio. After converting the code and debugging, the apps can be published as full Universal Windows Apps. They can then be rolled out for all Windows systems and access all APIs that Windows apps can also use. It is therefore possible that you will soon see a popular app that you know from your iPhone or iPad on a Windows PC or tablet, where support for voice control or a stylus has been added, for example.

Old Windows applications

The projects to bring older Windows apps and web apps to Windows 10 are known as Centennial and Westminster respectively. Legacy Windows software in wpf, Windows Forms and win32 formats can be converted from their msi package to an appx package and then have access to all Windows 10 APIs, not just those for Cortana, notifications and Live Tiles. Converted old Windows programs are therefore full Universal Windows Apps and can link to all features of the Windows platform.

The project seems like a great opportunity for developers to dust off their old programs and provide them with new functionality, bring them to new system types and sell them securely. According to Microsoft, there are more than 16 million old .NET and Win32 applications that could potentially be included in the Windows Store, but the question is how many developers are willing to convert their old creations.

Finally, Microsoft makes it possible to place web apps in an appx package and publish them in the Store. The apps can then call Windows APIs with javascript, and they can also mix native code with the code for the web app. The group made little known about Project Westminster, as it is called. The four projects will go live in the summer of 2015, so more details about the bridge toolkits will appear then.


According to Microsoft, the biggest advantage of the ‘bridges’ for developers is that the apps can be sold in the Windows Store. Now that Store is not very popular yet, so Microsoft has to work hard to expand that store with new functionality. Earlier, Microsoft announced that music and video will be sold in the store and at Build 2015, the software group announced that a special Windows Store for Business will be launched.

Business apps are given their own category in the Windows Store, and developers can sell their apps to organizations in bulk. With the Business Store for Windows 10, companies can manage the apps they use and roll them out in large numbers.

In addition, the store will receive support for carrier billing so that people without a credit card can also make purchases and there will be an option to take out subscriptions via the Store. Finally, Microsoft promises to promote apps more clearly in Windows 10, not only through the Start menu, but also through Cortana and on the lock screen, as part of the Windows Spotlight feature to use that screen for suggestions.

Microsoft also gave some new figures on the use of the Windows Store to indicate the growth, but what became especially clear is that the numbers are still dwarfed by those of Android and iOS.

One app for all platforms

The Universal Windows Platform didn’t just come out of the blue. Cross connections between the Windows versions were also made in previous Windows versions, but from Windows 10 the different versions really have to continue as a single platform. Apps for Windows will become Universal Windows Apps from then on. Now that Microsoft also wants to attract old Windows software, web apps and apps from other platforms with the four Bridges, the term Universal Windows Platform has a much broader meaning: Windows as a platform for all apps.

What is Universal Windows App again? Initially, it will mean a lot to developers. They will be able to limit themselves to a single codebase during development and roll out apps to various Windows systems with little effort, from laptops and the Xbox One, to the HoloLens and internet-of-things devices. While apps may look different on those devices, they have a lot of similarities, whether under the hood or not.

For example, they must adhere to the ‘Windows 10 App Model’. That model defines the entire app lifecycle, from installing, updating, resource management, resume management, integration with the OS and the other apps, to final uninstallation. In terms of packaging, all universal Windows apps are in the appx format, which is already used for Windows Store apps.

Developers can easily target multiple device types and form factors with a single basic design . Among other things, the screen size, the hardware, whether or not there is a touchscreen, and so on are important. The same navigation and content will have to be positioned differently on the small screen of a smartphone than on a large screen, something that is familiar territory for developers of responsive websites.

Last but not least , universal Windows apps have access to a large amount of APIs that bring more than 2500 new features to Windows 10, such as DirectX12, Continuum for phones, holograms, game controllers and DirectInk for smooth stylus drawing.

Preliminary conclusion

Apple is making it attractive for iPhone users to use OS X and Google is focusing on web apps and running Android apps within Chrome, but it’s Microsoft that’s by far the most advanced in rolling out a universal platform for applications. The group is really doing everything it can to make it as easy as possible for developers to bring apps to its Universal Windows Platform and is not afraid to play borrowing neighbours. The company also has to get some connection to the spacious app platforms of Google and Apple. You can’t deny Microsoft guts and perseverance, but the question remains to what extent developers and consumers still want to express their love for Windows in a world that is increasingly dominated by Android and iOS.