Aggregation from multiple perspectives by roles

摘要

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. Different perspectives share the same atomic parts. Role classes and objects support multiple perspectives on the aggregation of a whole with same atomic parts.