When Apple debuted its Handoff technology in 2014's iOS 8 and OS X Yosemite, I was excited by the notion of liquid computing, in which both data and application state move from one device to another as you do. Apparently, the technology didn't excite many others, as it's rarely implemented outside of Apple apps, and most users aren't aware of it, unless perhaps they happen to have an Apple Watch.
Now, as announced last week at the Build 2016 developer conference, Microsoft is prepping for the release of Project Rome APIs for Windows PCs and smartphones, and -- having largely given up on owning the mobile platform -- it plans to release SDKs for iOS and Android, though not for OS X, since Microsoft remains unwilling to accept its decline on the desktop.
Project Rome is both similar and dissimilar to Handoff, and those differences perhaps will help it gain broader adoption than Handoff has attained.
Before I explain how the two compare, I should note that Microsoft previously introduced some cross-device capabilities in Windows 8. But those are more like Apple's other, older Continuity services managed via the cloud, such as syncing bookmarks and settings across devices tied to the same account.
Apple's Handoff and Microsoft's Project Rome are about federating apps across multiple devices, not simply syncing metadata. In Apple's case, that means recent models of Macs, iPhones, iPads, iPod Touches, and Apple Watches running iOS 8 or OS X Yosemite or later. In Microsoft's case, that means Windows PCs and Windows Phones running Windows 10 or later, as well as iOS and Android devices whose versions have yet to be revealed.
What Apple's Handoff does
Handoff is focused on, well, handing off an application state from one device to another. For example, if you are composing an email in the Mail app on your iPhone and you get near your Mac, the Mac will see Mail running on your iPhone and offer to transfer that in-progress message from the iPhone to the Mac, launching Mail on the Mac in the process.
The devices detect each other via Bluetooth and Wi-Fi Direct, and they automatically pair if they use the same Apple ID (and if Handoff is enabled, of course).
What's key is that Handoff relies on the receiving device to make the transfer happen; the idea is that the user has moved to a different device and wants to pull in what he or she had been working on previously. It's not about controlling another device.
The most common uses of Handoff that I see in the real world are with the Apple Watch and with the iPhone. The Apple Watch can pick up phone calls, text messages, and email messages from the iPhone using Handoff. And a Mac or iPad can answer a call on an iPhone or interact with a text sent to an iPhone, via Handoff.
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