Android was unveiled in 2007 as a free, open-source mobile operating system. From the beginning, we intended Android to be scaled across a variety of manufacturers. We knew that consistency of API was important for developers, so we created a compatibility program for the Developer API specified by the Compatibility Definition Document (CDD) and its associated Compatibility Test Suite (CTS), now comprising over a million tests.
The result today is that app developers can write a single app that works across over a billion devices running on different hardware from different manufacturers.
Project Treble aims to do what CTS did for apps, for the Android OS framework. The core concept is to separate the vendor implementation — the device-specific, lower-level software written in large part by the silicon manufacturers — from the Android OS Framework.
This is achieved by the introduction of a new vendor interface between the Android OS framework and the vendor implementation. The new vendor interface is validated by a Vendor Test Suite (VTS), analogous to the CTS, to ensure forward compatibility of the vendor implementation.