Developing Energy-Aware Software

ion over Component Behavior RUMs abstract over the behavior of a component, which we define as all possible execution sequences of that component. For RUMs, there are two kinds of abstraction to consider: Over-abstraction An over-abstraction (also called an overapproximation) specifies a superset of the possible execution sequences of a component. If we verify a property that holds for all execution sequences in the over-abstraction, then it also holds for the execution sequences in the actual concrete system. For example, an over-abstraction can be used to prove an upper bound of the maximum energy consumption of the actual system and a lower bound of the minimum energy consumption. Thus, overabstractions provide guarantees of the component. Under-abstraction An under-abstraction (also called an underapproximation) specifies a subset of the possible execution sequences of a component. If we verify a property for some execution sequence in the under-abstraction, then that computation is also in the actual system, and the property holds there too. For example, an under-abstraction can be used to find an execution sequence that gives a lower bound of the maximum energy consumption and an upper bound of the minimum energy consumption of the actual system. Thus, under-abstractions give possibilities of the component. The coffee machine in figure 23a provides an example. Both specifications in figures 23b and 23c are abstractions of the coffee machine, because the specifications are smaller than