MOOD An architecture for object oriented access to a relational data base

Abstract

In this paper we describe MOOD, a system which may be used to easily and efficiently build C++ programs accessing a relational database. MOOD has its own data model, which is Object-Oriented, and supports object identity, generalization hierarchies, and object sharing; by processing schema definitions, the MOOD system builds a relational schema and a C++ Class Library that enable the interaction between a C++ programming environment and a conventional relational database. We associate a C++ class to each class in the MOOD schema. Methods of this class may be used to access, create or modify MOOD objects. In particular, MOOD primitives provide tools for expressing complex, set-oriented queries to extract objects by traversing the MOOD schema along semantics links. These primitives generate SQL queries in order to extract relevant tuples and assign them to C++ objects; the interface thus developed solves the impedence mismatch between C++ (recordoriented) and SQL (set-oriented).

MOOD can be used as a low-level programming environment for building applications; in particular, it is currently considered as an environment for implementing the Logidata+ language.

MOdena Object Database

This work has been partially supported by CINECA, CICAIA — Universitâ degli Studi di Modena, and by Progetto Finalizzato Informatica e Calcolo Parallelo, Subproject LOGIDATA+