Static Verification of UML Model Consistency

In a UML model, different aspects of a system are covered by different types of diagrams and this bears the risk that an overall system specification becomes inconsistent or incomplete. Hence, it is important to provide means to check the consistency and completeness of a UML model. Many approaches for model validation and verification rely on generation of suitable code which dynamically (i.e., at run-time) checks the validity of OCL constraints. This approach has several well-known drawbacks. For example, it cannot generally guarantee that a constraint will never be violated, unless an infinite number of tests is performed. On the other hand, even more desirable static approaches are not immune from weaknesses. The techniques based on model checking suffer from the state explosion problem and thus cannot scale to most system sizes. Moreover, the static approach is in general undecidable. In this paper we propose a static verification framework based of Abstract Interpretation techniques, a theory of approximation of mathematical structures. This framework, by using OCL constraints together with Class Diagrams, certifies that the dynamic part (Sequence Diagrams) of the model is satisfied. Our approach keeps the advantages of static verification and, at the same time, avoids the weaknesses of the other mentioned methods as it does not require users to build test scenarios and also it can make undecidable methods decidable, up to a specified level of precision.