Aggregation from Multiple Perspectives by Roles

Lars Kirkegaard B kdal Bent Bruun Kristensen The Maersk Mc-Kinney Moller Institute for Production Technology University of Southern Denmark/Odense University, DK-5230 Odense M, Denmark e-mail: flkb, [email protected] Abstract A whole is aggregated from parts, where a part can be aggregated itself or be atomic. The structure forms an aggregation (or part-whole) hierarchy. The whole can be modeled from multiple perspectives, where a perspective introduces its own aggregation hierarchy as well as dedicated properties for the whole and parts. Di erent perspectives share the same atomic parts. Role classes and objects support multiple perspectives on the aggregation of a whole with same atomic parts. 1: Introduction From a collection of atomic parts we construct multiple aggregation hierarchies. The overall aggregated whole is the same for all hierarchies. The hierarchies model alternative perspectives on the aggregated whole. The atomic parts form the basis for all the hierarchies. The whole is described in di erent ways by di erent hierarchies. The actual structures of the hierarchies are typically di erent, and the properties of the whole, atomic parts and other elements can di er according to the perspective. The hierarchies must describe the same identity, but from di erent perspectives as re ected by properties and structure of the hierarchies. Figure 1 illustrates multiple aggregation hierarchies for the the whole W and the atomic parts P1, P2, ... Pn. Only two perspectives, H1 and H2, are illustrated. W W