A Visualization for Client-Server Architecture Assessement

Maintaining large legacy systems often requires understanding their architecture. This is important since legacy system architecture decay over time and architecture violations may dramatically impact planned renovation actions. Merely reading source files is time-consuming and often highly inefficient. Visualizations have been proposed as a tool to support architecture understanding. Some software architecture visualizations decompose the software system architecture into layers, components, or slices from a structural viewpoint. Such visualizations, however, do not take into account the specificities of clientserver applications. They do not help maintainers identify and understand software architecture violations. In this paper, we propose CLISERVO, a new visualization to help software maintainers detect architectural violations in client-server systems. CLISERVO classifies client-server entities into different levels of dependencies, shared entities, or ambiguous entities (e.g., entities that belong abnormally to different layers). CLISERVO identifies and presents entities in their corresponding layers from two distinct viewpoints: global overview entities and violations, i.e ambiguous entities and illegal dependencies between layers. We validated our approach on three real-world industrial projects with access to their maintainers. We report the findings of 91 ambiguous entities, 29 purportedly shared and idle entities, 24 and 82 elements defined as shared but only used by the client or server, and 12 relations violating the layered architecture.