Discovery of architectural layers and measurement of layering violations in source code

The layers architectural pattern has been widely adopted by the developer community in order to build large software systems. In reality, as the system evolves over time, rarely does the system remain conformed to the intended layers pattern, causing a significant degradation of the system maintainability. As a part of re-factoring such a system, practitioners often undertake a mostly manual exercise to discover the intended layers and organize the modules into these layers. In this paper, we present a method for semi-automatically detecting layers in the system and propose a quantitative measurement to compute the amount of non-conformance of the system from the set of layered design principles. We have applied the layer detection method and the non-conformance measurement on a set of open source and proprietary enterprise applications.