Software Metrics Metamodel
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The OMG Structured Metrics Metamodel (SMM)[1] specification defines a standard Metrics Metamodel. It is a publicly available specification from the Object Management Group (OMG). SMM specifies a metamodel for defining, representing and exchanging both measures and measurement information related to any structured information model, such as the OMG Meta Object Facility (MOF™) standard, defining an XMI interchange format between metric extraction tools. It is used to maintain metrics by a number of other OMG specifications such as the Knowledge Discovery Metamodel and the Value Delivery Metamodel.
The SMM standard includes elements representing the concepts to express a wide range of diversified measures:
- Measures denote the re-usable definitions of how measurements are calculated.
- Measurements are the results of applying measures, via observations.
- Libraries maintain measures and their related information, such as characteristics and units-of-measure, providing re-use in different contexts.
Measures
SMM specifies the representation of measures without detailing the representation of the entities measured.
SMM defines representations for:
- Direct measures that are taken directly against a measurand. Examples include counts and named measures such as McCabe’s cyclomatic complexity (a software complexity metric)[2] or gross domestic product. Values may be imported or queried via SMM operations.
- Aggregate measures that are calculated from base measurements on features of a measurand. SMM operations specify the feature retrieval. Vote totals, volumes, and net profits can be defined as aggregate measures.
- Transmuting measures that rescale, grade or rank base measurements of a measurand. Fahrenheit to Celsius is a rescaling; clothes sizes of small, medium and large are grades; and customer satisfaction units derived from delivery time is a ranking.