A transaction-based temporal data model for real-time databases

We propose a real-time database model that deals with the temporal nature of data. Previous models assigned validity intervals with data items. A value of a data item is then only valid within the corresponding interval. In the new model, it is recognized that validity depends on the usage of the data item, therefore temporal validity is a characteristic of transactions, rather than of data items. The paper shows the influence of this different modeling on the expressiveness of the specification. It compares the transaction-based model with existing models that cover the same area, by looking at implementations that are based on these models.