Modern C++, modern apps:

How Microsoft is taking on the cross-platform challenge with Office

by Mary Jo Foley

Summary: Microsoft's Office team has a new approach designed to allow it to share more of Office's code across not just Windows, but also Android, iOS and the Web.

Note: This is a 50-minute version of the same talk given at CppCon in two one-hour sessions. After presenting this at CppCon, Igor was invited to present the information also at Facebook's @Scale.

See also Dropbox's CppCon talk about how Dropbox uses a similar architecture, and moved to C++ to enable a single cross-platform source base after initially having written separate apps in Java for Android and Objective-C for iOS.

From the article:

Zaika talked about Microsoft's Office cross-platform architecture strategy at the recent Facebook @Scale conference. ... In his 50-minute session, Zaika detailed how Microsoft is building Office across Windows, Apple, Android and the Web by using C++. ...

The goal is to maintain a shared core of intellectual property — the guts of Office — all written in C++ and keep that shared core as large as possible. By doing this, risks of document corruption are reduced. On top of that core, there is a set of native UX application programming interfaces. ...

The goal of "write once, run anywhere" which technologies like Java, Flash and HTML5 were designed to try to solve by pushing the level of abstraction as low as possible or making application programming interfaces (APIs) very broad sounded good, Zaika said, but ended up creating impedance mismatch. Compatibility and interoperability problems, among others, arose. "Either you blew up, or the OS (operating system) blew up," Zaika said. ...

With a common C++ core, a thin native UX layer and evolving PALs, Microsoft is building its Office apps so they work on different OSes with fairly little tweaking required. Zaika cited PowerPoint as an example, noting that only four percent of its tens of millions of lines are unique to the WinRT/Universal version of Office (the touch-first Office release some of us have been calling "Gemini"). If the XAML code is excluded, the amount of shared code is 98.6 percent he said. The PowerPoint for Android code base includes 95 percent shared code, Zaika said.