Abstract types and storage types in an OO-DBMS

A description is given of the Vbase object-oriented database management system (OO-DBMS), which extends the basic paradigm offered by other object-oriented systems by allowing the creation of storage classes, in the same way that other systems allow the creation of abstract classes. Storage classes control object storage, including dereferencing, object faulting, clustering, sharing and persistence. The notion of a storage manager, upon which this facility is based, is introduced, and it is shown how it is used in Vbase. Storage managers are types, which are organized into a hierarchy similar to but orthogonal to the hierarchy of abstract types. The storage-manager-type hierarchy is user-extensible by subtyping, just as the abstract type hierarchy is. The implementation of the storage-manager abstraction relies on generalizations to operation dispatching and reference resolution. Some features of the current implementation of Vbase and some experiences with it are described.<
>