Real time data consistency in component based embedded systems

Embedded systems use more and more distributed architectures. For example, several instrumentation components communicate with a calculator via a field bus. Such distributed systems need to be sufficiently deterministic despite the asynchronous characteristics of their hardware components. This work fits in with these problematics and focuses on the control of the temporal compatibility of a set of interdependent data used by the components of the system. Indeed, even if the components keep a simple behaviour, periodic for example, latencies in computation and communication can cause inconsistencies during the use of these data. The study focuses on the data consistency formalisation by defining a relation called influence. The data flow between components is abstracted to a graph and, from the definition of particular subgraphs called spindles, a data timestamping rule is elaborated. It permits to define consistency constraints using constraints on these timestamps.