UC Berkeley

This paper uses interface automata to develop an interface theory for a component architecture for Internet of Things (IoT) applications. Specifically, it examines an architecture for IoT applications where so-called “accessors” provide an actor-oriented proxy for devices (“things”) and services. Following the principles of actor models, an accessor reacts to input stimuli and produces outputs that can stimulate reactions in other accessors or actors. The paper focuses on a specialized form of actor models where inputs and outputs to accessors and actors are time-stamped events, enabling timing-sensitive IoT applications. The interaction between accessors and actors via time-stamped events forms a “horizontal contract,” formalized in this paper as an interface automaton. The interaction between an accessor and the thing or service for which it is a proxy is a “vertical contract,” also formalized as an interface automaton. Following common practice in network programming, our vertical contract uses an asynchronous atomic callback (AAC) pattern. The formal composition of these interface automata allows us to reason about the combination of a timed actor model and the AAC pattern, enabling careful evaluation of design choices for IoT systems.