Charles W. Bachman
Inheritance and Role Modelling: Converging Concepts in Data
Entity Relationship modelling, developed from the Data Structure Diagrams of the 1960’s. The relationships of the ER model represent associations between entities without really clarifying what the entities represented. Role Modelling brings a new dimension to data modelling where the focus is on an entity as the representative of a particular role that is being played by a business entity and where there is a need to define and constrain the set of roles that any single business entity might play.
Inheritance came into the data modelling and programming worlds through the influence of Object Oriented Analysis and Artificial Intelligence. Viewed narrowly, it represents a study of generalisation and specialisation. Its objectives, following a long term trend in computer science, are both simplification and reuse.
Computer Science, as any new field of study, borrows words with accepted usage that suggest the new concepts that it wishes to teach. “Inherit”, “hybrid”, “role”, “evolution”, and “taxonomy” are words that have accepted usage in the fields of Botany, Zoology, Psychology and the Law. The challenge is to learn what they mean or do not mean in the computer science community. E.g.
Inherit: 1) To receive (property) from a person by legal succession or will. 2) Biology: To receive genetically from an ancestor.
Hybrid: An offspring of two genetically dissimilar animals, or plants, as members of different varieties, species, or breeds.
Role: A part played by an actor.
Evolution: The theory that existing species of plants and animals have developed from previously existing species through a process of gradual change.
Taxonomy: The science, laws, or principles of classifying living organisms in specially named categories based on shared characteristics and natural relationships.
The challenge ahead is how to reconcile these concepts that largely overlap in their physical manifestation, but which are conceptually quite different. Are both needed?
Charles W. Bachman needs no introduction to IRMAC members. Please join him again for an interesting and thought-provoking presentation.