  Model-based development is a widely-used method to describe complex systems
that enables the rapid prototyping. Advances in the science of distributed
systems has led to the development of large scale statechart models which are
distributed among multiple locations. Taking medicine for example, models of
best-practice guidelines during rural ambulance transport are distributed
across hospital settings from a rural hospital, to an ambulance, to a central
tertiary hospital. Unfortunately, these medical models require continuous and
real-time communication across individual medical models in physically
distributed treatment locations which provides vital assistance to the
clinicians and physicians. This makes it necessary to offer methods for
model-driven communication and synchronization in a distributed environment. In
this paper, we describe ModelSink, a middleware to address the problem of
communication and synchronization of heterogeneous distributed models. Being
motivated by the synchronization requirements during emergency ambulance
transport, we use medical best-practice models as a case study to illustrate
the notion of distributed models. Through ModelSink, we achieve an efficient
communication architecture, open-loop-safe protocol, and queuing and mapping
mechanisms compliant with the semantics of statechart-based model-driven
development. We evaluated the performance of ModelSink on distributed sets of
medical models that we have developed to assess how ModelSink performs in
various loads. Our work is intended to assist clinicians, EMT, and medical
staff to prevent unintended deviations from medical best practices, and
overcome connectivity and coordination challenges that exist in a distributed
hospital network. Our practice suggests that there are in fact additional
potential domains beyond medicine where our middleware can provide needed
utility.
