The construction process relies on a modeling language, because developers need to build visual models and discuss them with stakeholders and fellow developers. The approach uses the object-oriented modeling language UML for requirements specification and sys- tem design. It is an advantage to use UML, because it differs from other modeling lan- guages such as Data Flow Diagrams. It enables to use a common set of terms and concepts throughout the whole modeling process. In addition, object-orientation is the very basis of learning objects.