Multiple-parameter coupling metrics for layered component-based software

Coupling represents the degree of interdependence between two software components. Understanding software dependency is directly related to improving software understandability, maintainability, and reusability. In this paper, we analyze the difference between component coupling and component dependency, introduce a two-parameter component coupling metric and a three-parameter component dependency metric. An important parameter in both these metrics is coupling distance, which represents the relevance of two coupled components. These metrics are applicable to layered component-based software. These metrics can be used to represent the dependencies induced by all types of software coupling. We show how to determine coupling and dependency of all scales of software components using these metrics. These metrics are then applied to Apache HTTP, an open-source web server. The study shows that coupling distance is related to the number of modifications of a component, which is an important indicator of component fault rate, stability and subsequently, component complexity.

Srini RamaswamyEmail: Email:

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Liguo Yu   received the Ph.D. degree in Computer Science from Vanderbilt University. He is an assistant professor of Computer and Information Sciences Department at Indiana University South Bend. Before joining IUSB, he was a visiting assistant professor at Tennessee Technological University. His research concentrates on software coupling, software maintenance, software reuse, software testing, software management, and open-source software development. Kai Chen   received the Ph.D. degree from the Department of Electrical Engineering and Computer Science at Vanderbilt University. He is working at Google Incorporation. His current research interests include development and maintenance of open-source software, embedded software design, component-based design, model-based design, formal methods and model verification. Srini Ramaswamy   earned his Ph.D. degree in Computer Science in 1994 from the Center for Advanced Computer Studies (CACS) at the University of Southwestern Louisiana (now University of Louisiana at Lafayette). His research interests are on intelligent and flexible control systems, behavior modeling, analysis and simulation, software stability and scalability. He is currently the Chairperson of the Department of Computer Science, University of Arkansas at Little Rock. Before joining UALR, he is the chairman of Computer Science Department at Tennessee Tech University. He is member of the Association of Computing Machinery, Society for Computer Simulation International, Computing Professionals for Social Responsibility and a senior member of the IEEE.