Chapter 23 - Product metrics (cont). In this chapter, the following content will be discussed: Measurement and quality assessment, framework for product metrics, metrics for requirements model, metric for design model. | Product Metrics SEII-Lecture 23 Dr. Muzafar Khan Assistant Professor Department of Computer Science CIIT, Islamabad. 1 Recap Measurement and quality assessment Framework for product metrics Measure, measurement, and metrics Formulation, collection, analysis, interpretation, feedback Principles for metrics characterization and validation Metrics for requirements model Function-based metrics Metrics for specification quality Metric for design model Architectural design metrics Metric for object-oriented design 2 Class-Oriented Metrics [1/3] Weighted methods per class (WMC) n methods of complexity c1, c2, cn for a class C WMC = ∑ci for i = 1 to n If complexity increases, more efforts are required Limited reuse Counting methods apparently seems straightforward Consistent counting approach is required Depth of the inheritance tree (DIT) Maximum length from the node to the root If DIT grows, lower-level classes inherit many methods Many methods may be reused Leads to design complexity 3 Class-Oriented Metrics [2/3] Number of Children (NOC) Immediate subordinate classes NOC grows Reuse increases Abstraction of parent class may be diluted Testing effort increases Coupling between class objects (CBO) If coupling increases Reusability decreases Testing and modification complicated CBO as low as reasonable 4 Class-Oriented Metrics [3/3] Response for a class (RFC) Methods potentially executed in response to message received by a class object RFC increases, design complexity and testing increases Lack of cohesion in methods (LCOM) Number of methods that access one or more of the same attributes If no methods access same attribute, LCOM is zero If LCOM high, complexity of design increases 5 Component-Level Design Metrics [1/3] Metrics for conventional components focus on internal characteristics of a component Cohesion metrics Data slice Backward walk through a module to look data values Data tokens Variables defined Glue tokens Data tokens lies on data slice Superglue tokens | Product Metrics SEII-Lecture 23 Dr. Muzafar Khan Assistant Professor Department of Computer Science CIIT, Islamabad. 1 Recap Measurement and quality assessment Framework for product metrics Measure, measurement, and metrics Formulation, collection, analysis, interpretation, feedback Principles for metrics characterization and validation Metrics for requirements model Function-based metrics Metrics for specification quality Metric for design model Architectural design metrics Metric for object-oriented design 2 Class-Oriented Metrics [1/3] Weighted methods per class (WMC) n methods of complexity c1, c2, cn for a class C WMC = ∑ci for i = 1 to n If complexity increases, more efforts are required Limited reuse Counting methods apparently seems straightforward Consistent counting approach is required Depth of the inheritance tree (DIT) Maximum length from the node to the root If DIT grows, lower-level classes inherit many methods Many methods may be reused Leads to design complexity 3 .
