Multi-Level Domain Modeling with M-Objects and M-Relationships

Using traditional semantic data modeling, multi-level modeling can be achieved by representing objects in different abstraction hierarchies, namely classification, aggregation and generalization. This, however, leads to accidental complexity, complicating maintenance and extension. Several modeling techniques, like deep instantiation, powertypes and materialization, have been proposed to reduce unnecessary complexity in modeling objects at multiple levels. Multilevel objects (m-objects) and multi-level relationships (m-relationships) build on these results and provide a natural, intuitive representation of the concretization of objects and relationships along multiple levels of abstraction. By integrating aspects of the different abstraction hierarchies in a single concretization hierarchy, they improve readability and simplify maintenance and extension as compared to previous approaches. The discussion on conceptual modeling is complemented by a brief presentation of M-SQL, a data manipulation and query language for working with m-objects and m-relationships in an objectrelational setting.