For building universal apps, Microsoft also released Visual Studio 2013 Update 2 RC as a download.
Todd Brix, general manager of Windows apps and Windows Store, also published a blog post showing an example of the new symbol that customers will see in coming weeks for a unified Windows app. It will be up to developers to decide whether they want to charge users per-app or per-device for a universal app — or whether they want to release an app for free, he said.
Brix also said that the existing tiered revenue sharing model for apps will be phased out as of Dec. 31, with Microsoft adopting an industry standard 70/30 revenue split. "We're confident that the vast majority of developers will be more successful within the more unified Store structure and policies," Brix said.
Will universal apps fly?
"Windows 8.1 will encourage developers to move to universal Windows apps," Gartner's Baker said. "What's the downside? If your app can run across Windows Phone, Windows Tablets and PCs, why wouldn't you do that? It increases the appeal to consumers."
The ability for apps to port across all of a user's devices "is huge," said Ramon Llamas an analyst at IDC. In theory, the plan could push Microsoft ahead of Android and iOS, he added. "Where does Google stop and Chrome begin and where does iOS stop and the Mac OS begin?" he asked.
But Gold said Microsoft has been trying to consolidate app development for years. "The vision of one code base for all platforms is nice, but it won't happen in the short term due to the need for optimizing the OS to each device," he said. "That means there will continue to be specific apps and environments for different platforms for three to four years, at least."
Several analysts said Microsoft needs to eventually combine the Windows Store and the Windows Phone Store to attain the ultimate unified app environment.
Having a single store "would make it much easier for users in discovery and management of apps," said Carolina Milanesi, an analyst at Kantar Worldpanel.
But Gold said that there's still some appeal to keeping phone apps separate from other Windows apps, in separate stores. "Phone users often want to go to a specific place to find apps, like going to a specialty store like a sporting goods store instead of a full-blown retailer like Walmart," he said.
Patrick Moorhead, an analyst at Moor Insights & Strategy, said he would have liked it if Microsoft had talked more at Build about what's known as "modularity" — a concept that applies to scenarios where a user with a phone or phablet could walk into an office, place the device on a desk and have it connect wirelessly to a display, mouse and keyboard with all the data processing done on the phone with connections to the Internet and cloud data and services.
Moorhead said that unified apps are a kind of modular development approach to enable apps to be written once for many devices. "In that scenario," he explained, "it is easier to work with or watch content on any device."
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