A quality model for evaluating maintainability of object-oriented software systems
AbstractMeasuring software maintainability is of vital importance for improving software product quality. Using a software quality model in the development life cycle, the quality of the system can be continuously evaluated and improved to reduce the maintenance cost. According to ISO/IEC 25010 Software Quality Models Standard, the maintainability characteristic of software product quality is composed of five sub characteristics; modularity, modifiability, reusability, analyzability and testability. This paper proposes a quality measurement model to evaluate the maintainability of software classes in terms of their reusability and modifiability characteristics in large-scale software systems. The model is based on software properties that are strongly related to reusability and modifiability, such as size, complexity, cohesion, coupling, and inheritance. First, our method categorizes metric values of software classes in the test system as low, medium and high. This categorization is done based on the average and median values for these metrics that are obtained from reference software systems. Then, the proposed measurement method uses the levels of the metrics to calculate the reusability and modifiability scores of each class in the system. The scores fall in one of the five categories; very low, low, medium, high, and very high. The developers of the software system can examine classes with low and very low scores and then refactor them if necessary. This continuous evaluation and refactoring during the development can increase the quality of the system and reduce maintenance costs. We applied our model on two largescale industrial mobile applications and discussed the results with the development teams of the systems. We saw that our approach could reasonably grade classes on their reusability and modifiability characteristics.