Measuring class coupling and cohesion: a formal metamodel approach

Metamodeling, object-orientation and formal methods are three promising ways to cope with the increasing size and complexity of today´s software systems. Furthermore, effective control of development projects requires the use of versatile metrics for software size and complexity. We present a generic formal object-oriented metamodel (GM), specifically tailored for modeling object-oriented software systems, and use it as the foundation for defining two basic measures of structural quality: coupling and cohesion. Even though these two notions are generic, we restrict ourselves to defining them at the class level, which is probably the most useful for object-oriented systems. The metrics have a generic formal definition, which makes them simple, intuitive, and amenable to automated measurement.