Abstract
Nowadays software developers are moving from conventional software process technologies to the object-oriented paradigm. To develope the object-oriented softwares efficiently, various software metrics have been suggested. Coupling refers to the degree of independence between components of the system. It has long been well known that good software practice calls for minimizing coupling interaction. Many researches have been studied coupling metrics of the object- oriented systems. We review Chidamber and Kemerer's work & Li's work. In this paper, we study the coupling of the overall structures of object-oriented systems by analyzing the class diagram of UML. We propose four coupling metrics for object-oriented softwares. First, we use an established coupling metric for object- oriented systems as a basic coupling metric. Then we modify the basic coupling metric by including indirect coupling between classes, We also suggest two relative coupling metrics to measure coupling between subsystems. We investigate the theoretical soundness of the proposed metrics by the axioms of Briand et al. Finally, we apply the presented metrics to a practical case study. This coupling metric will be helpful to the software developers for their designing tasks by evaluating the coupling metric of the structures of object-oriented system and redesigning tasks of the system.