Note: [] Address for correspondence: University of Turku, Finland
Abstract: A deterministic behavior of systems composed of several modules is a
desirable design goal. Assembling a complex system from components requires
also a high degree of re-usability. The compatibility of the selected
components may become a problem even at abstract design levels, due to possible
different degrees of model determinacy, possible different execution models,
etc. In this cases, an overall deterministic system behavior is difficult to
achieve. The development of communication mechanisms between such components
will have then to accommodate the differences, so that both correct processing
and information exchange (data and control, appropriate choices and relative
timing or sequencing) are achieved. For instance, human-machine interaction
offers a good example of cooperation between deterministic models (machines)
communicatingwith highly non-deterministic counterparts (the human models, if
not restricted). We analyze here such communication mechanisms by
"confronting" synchronized and un-synchronized models
of execution, in the framework of action systems, a state based formalism. We
"force" the two models to coexist within the same
context and explore the possibilities of building trustworthy communication
channels between them. We base our approach on a combined polling - interrupt
scheme, which allows us to mitigate communication issues that may otherwise
compromise the correct input-output system behavior. More robust system models
are obtained by applying specific correctness rules of refinement. We
illustrate our methods on an audio system example, implementable as either a
software or a hardware device.
Keywords: System modeling, synchronized / interleaved communication, action systems
