Ensuring Interoperability for the Internet of Things: Experience with CoAP Protocol Testing

Constrained Application Protocol (CoAP) is a specialized web transfer protocol, designed for realizing interoperation with constrained networks and nodes for machine to machine applications like smart energy, building automation, etc. As an important ubiquitous application protocol for the future Internet of Things, CoAP will be potentially implemented by a wide range of smart devices to achieve cooperative services. Therefore, a high level of interoperability of CoAP implementations is crucial. In this context, CoAP Plugtest the first formal CoAP interoperability testing event was held in Paris, March 2012 to motivate vendors to verify the interoperability of their equipments. The event turned to be successful due to our contribution, including the test method and tool. This paper presents the testing method and procedure for the CoAP Plugtest event. To carry out the tests, a set of test objectives concerning the most important properties of CoAP have been selected and used to measure the interoperability of CoAP implementations. The process of verification has been automated by implementing a test validation tool based on the technique of passive testing. By using the test tool, a number of devices were successfully tested.