Abstract. In this paper, we propose an object-oriented version model which presents temporal concepts to store not only the object lifetime but also the history of dynamic attributes and relationships defined in the versioned objects and versions. One of the main features of our model is the possibility of having two different time orders, branched time for the object and linear time for each version. The model supports integration with existing databases, by allowing the modeling of normal classes among the temporal versioned classes. Finally, an approach to its implementation on top of a commercial database is presented.

A temporal data model can be used to specifi not only static but also dynamic aspects of an application, allowing to record the evolution of its objects. Conventional applications commonly use the concept of transaction to update information, while unconventional applications require managing many database states to keep the update history. To fulfill this request, the concept of version is presented. The main purpose of this work is to present an alternative for the union of temporal data and a version model. The result, the Temporal Versions Model, is able to store the object versions and, for each version, the history of its dynamic properties and relationships values. One of the most interesting features of our model is the possibility of having two diflerent time orders, branched time for the object and linear time for each version. The model still supports integration with existing databases, by allowing the modeling of normal classes among the temporal versioned classes. ' .