Expressing and Validating OCL Constraints using Graphs

The definition of the semantics of visual languages, in particular Unified Modeling Language (UML) diagrams, using graph formalism has known a wide success, since graphs fit the multi-dimensional nature of this kind of language. However, constraints written in Object Constraint Language (OCL) and defined on these models are still not well integrated within this graph-based semantics. In this chapter, the authors propose an integrated semantics of OCL constraints within class diagrams, using graph transformation systems. Their contribution is divided into two parts. In the first part, they introduce graph constraint patterns, as the translation into graphs of a subset of OCL expressions. These patterns are validated with experimental examples using the GROOVE toolset. In the second part, the authors define the relation between OCL and UML models within their graph transformation system.