A commonly used methodology in the design of a database system is to use the ER Model for the conceptual design together with the RDM during the implementation phase. This methodology requires that a mapping between the two data models be performed.
This paper addresses the `lost semantics' problem caused by the impedance mismatch between the two models and reports on a prototype system which has been developed in order to bridge this gap. The aim of the system is to provide a tool for preserving the semantics of a conceptually rich model when automatically translating it into a working system.
The graph oriented approach suggested by Dogac [Dog90] makes use of the implicit information from the ER Schema when identifying the correct update propagations. They suggest a preprocessor which must be run on all applications for this automatic generation of relational code. We take this a stage further and suggest how, using the
emerging active technology of new DBMS, the techniques can be used to provide full, automatic and centralised support for an ER design. Details of an initial prototype (for non-active systems) and a refined prototype (for the latest release of a system, with triggers) are provided.
There are a number of aspects to the architecture which has been developed: it is multi-level, for targeting different database systems; it preserves the ER Model in the working system; it can be used for both active and passive database systems. The early (passive) prototype has been designed to run on top of the commercial RDBMS
INFORMIX. Work on both the passive and active designs targets the commercial RDBMS INFORMIX; the active design uses a general intermediate form of ECA rule as a target for translation.
Skövde: University of Skövde , 1993.