T-ODMG: an ODMG compliant temporal object model supporting multiple granularity management

In this paper we investigate some issues arising from the introduction of multiple temporal granularities in an object-oriented data model. Although issues concerning temporal granularities have been investigated in the context of temporal relational database systems, no comparable amount of work has been done in the context of object-oriented models. Moreover, the main drawback of the existing proposals is the lack of a formal basis-which we believe is essential to manage the inherent complexity of the object-oriented data model. In this paper, we define a comprehensive temporal object-oriented data model supporting multiple temporal granularities. We formally define the main notions of the data model such as types, legal values, classes, and objects. We address issues related to inheritance, type refinement, and substitutability. Finally, we describe the implementation of the presented model on top of an ODMG compliant DBMS.