Models of Connected Things: On Priced Probabilistic Timed Reo

The Internet of Things (IoT) is announced to swamp the world. In order to understand the emergent behaviour of connected things, effective support for the modelling of connection and failure probabilities, execution and waiting times, as well as resource consumptions of various kinds is needed. At the heart of IoT are flexible and adaptive communication and interaction patterns between things, meant to enable advanced as well as radically new emerging functionalities. Since these interaction patterns are determined by topological characteristics, they can naturally be modelled by channel-based exogenous coordination primitives. In this paper, we tackle the IoT modelling challenge. Our modelling approach is based on a conservative extension of Reo circuits. On a technical level, we work with a model called Priced Probabilistic Timed Constraint Automaton, which combines existing models of probabilistic and timed aspects, and is equipped with pricing information. The latter enables us to reason about resource consumption, especially important in light of severely limited power, memory and computation budgets in things. The approach is set up in such a way that the original constituent models can be retrieved without changes in syntax and semantics. A small but illustrative IoT case is modelled and evaluated, demonstrating the principal benefits of the proposed approach.