Instance modeling – beyond object-oriented modeling

Most object-oriented methodologies assign to instance models a minor role, using them to depict behavior scenarios and to show examples. For a large number of applications, among which enterprise models represent an outstanding example, traditional class-based models are not sufficient as tools. An enhanced object-oriented modeling methodology has to be devised in order to face the problems that instance models present. The main problem with using instance models to describe large and complex systems, such an enterprise, is the size of the resulting model. Thus the model needs to be organized and managed in an effective way. In addition CASE tools are needed, which provide a valid support to the construction of instance models. In particular the conformance of an instance model to a class model must be guaranteed. The OPJ approach is presented which tries to solve both organization and tool-oriented problems. A case study concerning enterprise modeling is used to show the main features of the proposed approach. The proposed methodology requires a suitable visual modeling environment, which implements the operational concepts that make up the methodology.