Reactive types for dataflow-oriented software architectures

Digital signal processing (DSP) tools, such as Ptolemy, LabView and iConnect, allow application developers to assemble reactive systems by connecting predefined components in generalised dataflow graphs and by hierarchically building new components by encapsulating subgraphs. We follow the literature in calling this approach dataflow-oriented development. Our previous work has shown how a new process calculus, uniting ideas from previous systems within a compositional theory, can be formally shown to capture the properties of such systems. This paper first recasts the graphical dataflow-oriented style of design into an underlying textual architecture design language (ADL) and then shows how the previous modelling approach can be seen as a system of process algebraic behavioural types for such a language, so that type checking is the mechanism used to statically diagnose the reactivity of applications. We show how both the existing notion of behavioural equivalence and a new behavioural preorder are involved in this judgement.