Sailfish OS - Mobile Operating System
Sailfish OS is a mobile operating system built on top of Mer project and Qt5. The UI is built with QML and QtQuick2 and Wayland. It is compatible with Android.
The Sailfish OS architecture is primarily made up of three areas — the base kernel layer, the middleware layer and the app/UI layer:
In the base layer, Sailfish OS uses a Linux kernel with hardware-specific additions. Hardware support is implemented by the Board Support Package (BSP) and Hardware Abstraction Layer (HAL) and is project-specific, and is typically kept private for commercial ports.
In the middleware layer, Mer provides the core system components for building services above the hardware and kernel level. Android emulation is provided by libhybris, which bridges Linux libraries based on GNU C with those based on Bionic, such as Android.
The Qt C++ application development framework provides the primary development libraries. Aside from the main Qt modules, Sailfish OS uses add-on modules such as Qt Maps, Qt Sensors and Qt Contacts. Also, all Sailfish applications are written with QML, a Qt technology for easily building user interfaces into C++ applications.