Flexible, Direct Interactions between CoAP-enabled IoT Devices

The wireless communication capability of sensors and actuators made them suitable for several automation solutions which involve sensing physical properties and acting upon them. These days, gateway or cloud based sensor/actuator interaction models are widely used. In this model, every sensor/actuator interaction goes through the gateway or via the cloud. In order to realize the true Internet of Things philosophy where everything is interconnected, direct interactions between sensors and actuators, also called bindings, are important. In this paper, we introduce a CoAP based sensor/actuator binding solution where a 3rd party is responsible for setting up the binding, but is not involved in any of the further interactions between the sensor and actuator. As binding creation and execution is fully based on Restful CoAP interactions, very flexible bindings between any two devices can be created. We implemented this solution in Contiki and evaluated the implementation by taking different measures such as delay, memory footprint, and packet size.