Object Versioning in Ode

The design of the versioning facilities in the Ode object-oriented database system is based on a few powerful concepts that allow implementation of a wide variety of versioning paradigms. These facilities have been cleanly integrated into Ode’s database programming language O++. Object versioning in Ode is orthogonal to type, that is, versioning is an object property and not a type property. Versions of an object can be created without requiring any change in the corresponding object type definition, all objects can be versioned, and different objects of the same type can have a different number of versions. Both dynamic and static bindings to version references are supported. Temporal as well as derived-from relationships between versions are maintained automatically. This paper presents the versioning facilities in Ode, gives their formal semantics, illustrates their power by modeling a design database in production use, and discusses their implementation. Modeling the design database reinforces our belief that the versioning facilities provided in Ode offer the right functionality. The dynamic binding of version references and the automatic maintenance of temporal relationships between object versions also make Ode suitable for developing historical databases and for supporting time in databases.