The Design And Implementation Of CoAP Over WebSocket

The concept of Internet of Things (IoT) was originally proposed almost twenty years ago. Over the past many years, IoT has gone through huge and rapid development, and the field of Wireless Sensor Network(WSN) has witnessed remarkable advancement in particular. Compared to the progress of WSN, the practical service and application of IoT still has a very long way to go. Although current industry standards can meet those equipments like smart phones, they are not quite suitable for constrained nodes which are often battery supported and has relatively lower processing ability. Driven by such demands, the IETF set up CoRE working group to design a RESTful application protocol which can perform better among constrained nodes in constrained environments.The protocol was named Constrained Application Protocol (CoAP) and it was later standardized as RFC 7252.This paper analizes the features and defect of the HTTP/CoAP proxy proposed in RFC 7252, and explains the CoAP over WebSocket proxy as well as its advantages over the HTTP/CoAP proxy. Then a design and implementation of CoAP over WebSocket based on Californium open-source framework is given. Performance tests and experiments have shown that the CoAP over WebSocket approach has some significant advantages over HTTP/CoAP proxy in term of response time and high concurrency requests processing ability.