Temporal composability [real-time embedded systems]

The constructive design of dependable distributed real-time systems out of pre-validated components requires precise interface specifications of the components in the temporal domain and in the value domain. This paper focuses on the temporal specification of interfaces in composable distributed real-time systems and establishes four principles of composability (independent development of nodes, stability of prior services, performability of the communication system, and replica determinism). It presents the temporal firewall interface that forms a fully specified operational interface of a component. The paper explains how the temporal firewall interface supports the four principles of composability. It then classifies interfaces from the point of view of composability and shows how these interfaces correspond to the time-triggered and event-triggered communication paradigms.