Abstract
Model Driven Development (MDD), or Model Driven Architecture (MDA) seems to be one of the frequently used buzzwords. The main principle is that we use heavily different models of the application during the development and maintenance.
OMG association promotes the idea that work with model may bring many new possibilities. The model can be used to generate the data structure and the skeleton of solution.
We can extract models of an existing system by the reverse engineering process to facilitate its understanding and treatment. We can perform various transformations above models, e.g. refactoring.
Modeling is currently presented using UML (Unified Modeling Language). Correct models in UML diagrams have to be completed by precise descriptions of the various integrity constraints.
For this purpose, the UML specification includes a special language called OCL (Object Constraint Language). The paper deals with the principles OCL language, illustrated on the examples.