Towards Improving OCL-Based Descriptions of Software Metrics

Because most metrics in the literature are described by natural languages, they can be interpreted in an ambiguous manner, which can be an obstacle to consistent understanding of them. To cope with this problem, many works have been performed to clearly describe metrics using Object Constraint Language (OCL). Although OCL can help avoid the problems of ambiguous description, metrics described in OCL are awkward and difficult, which can lead to incorrect description of metrics. In this paper, we propose a description language, named Metric Description Language (MDL) for simple and clear description of software metrics. MDL supports a modular description of complex metrics, aggregation function, and automatic navigation between entities. Moreover, a tool, named MetriUs, has been developed for computing metrics expressed in MDL against UML diagrams. In a case study, we have described various existing metrics using MDL and found that MDL can describe metrics in simpler expressions than OCL.