Microsoft officials went public with some new details about its strategy for enabling developers to write once and run on any version of Windows during a deep-dive session at Mobile World Congress on March 2.
For the last few years, Microsoft officials have been evangelizing the idea that "One Windows" running across a variety of device types will enable developers to create universal apps that will build on a single runtime, use an increasingly similar set of application programming interfaces (APIs) and developer tools and be available from a single store.
With Windows 8 and Windows Phone 8, Microsoft got a step closer to realizing its "One Windows" vision. But with Windows 10, the company is hoping to get a lot closer to this promised nirvana.
The new universal app platform (UAP) that Microsoft is building with Windows 10 will sit on top of the Windows core. The UAP is a superset of WinRT, the Windows 8 and Windows RT runtime, according to tweets from Matt Lacey (@mrlacey), who runs the Windows Apps London developer group.
Developers will be able to target different versions -- either a range or individual -- of the UAP, not the underlying version of Windows, according to Lacey. The UAP "is a versioned collection of versioned contracts," he explained.
Universal apps don't mean apps that look and work exactly the same across all device types. Microsoft is building "extension SDKs (software development kits) that will allow developers to build platform/device-specific elements while still building on top of a single binary, according to tweets from the event.
Microsoft officials were hoping to deliver a new preview test build of Windows 10 roughly every month. There was no February test build of Windows 10 for desktops, but a new one is expected some time in the coming weeks, as is one for Windows Phones.