  In this paper, we introduce Zest (REST over ZeroMQ), a middleware technology
in support of an Internet of Things (IoT). Our work is influenced by the
Constrained Application Protocol (CoAP) but emphasises systems that can support
fine-grained access control to both resources and audit information, and can
provide features such as asynchronous communication patterns between nodes. We
achieve this by using a hybrid approach that combines a RESTful architecture
with a variant of a publisher/subscriber topology that has enhanced routing
support. The primary motivation for Zest is to provide inter-component
communications in the Databox, but it is applicable in other contexts where
tight control needs to be maintained over permitted communication patterns.
