Lehrgebiet Informationssysteme

FB Informatik

VStore

The VStore DBMS is a prototype implementation of OVDM and, therefore, provides OQL at its interface. VStore exploits the object oriented database management system ObjectStore as access system and storage system. VStore's data system is implemented as an additional layer realized on top of ObjectStore. This additional layer maps OVDM structures to C++ structures managed by ObjectStore. Therefore, the tasks of this layer are schema transformation and query transformation. A major component is the OSOQL-compiler directly generating C++ code from OQL statements (DDL as well as DML). Besides the implementation of OVDM concepts by the mentioned transformation approach, we are using VStore as a realization platform for new concepts which can be assigned to the following areas: application programming interface (API), activity management (long transaction management) and a graphical user interface (VGUI) integrating ad hoc query facilities and browsing functionality.

An application programming interface (API) supports the development of C++ application programs with embedded OQL queries. The corresponding run-time system (also written in C++) provides checkout/checkin primitives, adapted hierarchical cursors as well as corresponding manipulation operators for object-buffer based manipulation of versioned data. This functionality is given to the application programmer through a class library alone. A preprocessor concept is not needed because of consequent use of the ADT concept and extensive generation of application dependent parts of the run-time system.