Assessing UML Model Quality by Utilizing Metrics

Utilizing metrics is an efficient mechanism to measure and evaluate the quality of models, since many well-known and accepted software metrics have been successfully transferred from the code level to the model level. In a modeling context, OCL seems to be a natural and qualified choice for expressing them, because of its expressiveness and its availability in modeling tools. The metrics employed in this contribution will be defined on a metamodel level, and their evaluation will be done in an automatically generated metamodel instantiation that reflects the model under consideration. The employed metrics cover both the class scope and the model scope, and software designers can define their own metrics. We introduce a complete process for model quality assessment with pre-defined metrics. In addition, a metrics configuration defined by an experienced chief designer can be translated into OCL invariants and be evaluated to give quality feedback to software designers relieving them from detailed OCL expertise. Our approach has been successfully integrated into a software design tool.