The diagram below gives an overview of the Android application frameworks (aka Linux user space components), that rely on Linux kernel.
This Linux kernel is based on the Android common kernel[1] following Google recommendation for its configuration[2].
It shows the main components, grouped per functional domains, but it does not intend to be exhaustive.
The Android framework is structured in several layers:
- The hardware interfaces providing a standard way to configure the underlaying driver, based on the Android HIDL (Hardware Interface Definition Language) mechanism
- The Android core (ART virtual machine, useful daemons (vold, adbd, debuggerd…) and system services)
- The Android services (providing interfaces to the application = SDK)
- The Android applications (including the launcher)
The Android services are often implemented partly in native cpp and partly in Java. The JNI (Java Native Interface) IPC mechanism is available to allow communication between the two worlds.
Additionally to the standard Android services, a proprietary coprocessor service for Android has been introduced (only for development purpose). The CoproService is composed of two parts:
- The firmware management (check running firmware, start/stop firmware, get/set name of the firmware)
- The TTY management (open/close and read/write the TTY interface). You have to implement your own protocol on top.