The Models of our Case Study
In our case study we construct three models of different systems:
- The model of the business system describes passenger services, meaning the business surroundings of the IT system. It deals with business processes, passengers, business partners, employees, etc. We discuss this model in Modeling Business Systems.
- The model of the IT system explains the IT system that was built for passenger services. The model of the passenger service business system serves as the foundation for the model of the IT system. We discuss this model in Modeling IT Systems.
- The model of system integration describes integration into the environment, especially gateways to the outside world. Here also, the model of the passenger service business system serves as the foundation. This model is discussed in Modeling for System Integration:
All three models are needed to build and integrate IT systems; the model of the IT system alone is insufficient. This is true not only for our case study, but also for all other cases.
You can see in Figure 2.9 that the model of the business system provides the foundation for all other models. In this way, it constitutes the basis to work from for everyone involved in the project. Because of this, it is of great advantage to use a unified modeling language, which can be understood by people from the different departments as well as from information technology. This enables a smooth exchange of models between the various areas. It also significantly eases verification of the models. We are convinced that UML functions as a link that has the ability to close the existing gap between the technical requirements and the actual performance characteristics of IT systems.