Temporality

Abstract

In this chapter, we deal with the fact that the world is far from static, and changes constantly, making the models that we construct today invalid tomorrow if the things that they represent change in a significant way. We explain why simply updating values and links is not sufficient to mitigate this and introduce the aspect-oriented notion of phase as a solution. Phases are object “slices” that are valid for a particular moment or period of time. We explain how phase selectors can be used on values and links to create diachronic instance models. Then, we introduce the notion of temporal features so that time-aware type models can be constructed and adequately connected to conforming instance models. Similarly, the notion of temporal aspect is described as a central time-oriented class in a type model. Finally, the chapter ends with a discussion of explicit temporal modelling in absence of phases by using specific class features to describe temporal validity.