Research On Interoperable Characteristics Between HTTP2 And CoAP For IoT

The Internet of Things(IoT)consists of traditional networks and constrained networks.It may go through one of the networks to another,in order to get IoT resources.Hyper Text Transfer Protocol(HTTP)is a common application layer protocol in traditional networks.Constrained Application Protocol(CoAP)is a common application layer protocol in constrained networks.Therefore,it is necessary to study the characteristics of the two protocols in order to interoperate with each other.The conversion between HTTP 1.1 and CoAP has been defined by IETF CoRE WG in RFC7252.However,in order to improve the performance of HTTP,HTTP2 was defined in 2015,has been supported by many Internet enterprises and has improved the performance of traditional networks.It is extremely obvious that the traditional networks will adopt HTTP2 protocol.In order to implement the interconnection of traditional networks and constrained networks,it is necessary to study the interoperable characteristics between HTTP2 and CoAP.In order to meet the needs of real-world application scenarios of the Internet of Things,this paper uses reverse proxy to make the conversion between HTTP2 and CoAP,and the proxy includes six modules that works with each other to support the interoperability between HTTP2 and CoAP.This paper proposes interoperable mothods between HTTP2 and CoAP in request-response pattern and publish-subscribe pattern.Two finite state machines are adopted for the two interoperable patterns of IoT to solve the conversion problem among the proxy modules,so as to solve the conversion between HTTP2 and CoAP protocols in the two interoperable patterns respectively.For the request-response pattern,this paper referes to the Reator model to make HTTP2 and CoAP proxy convert the two protocols efficiently.This paper proposes conversion processes for four methods based on HTTP2 and CoAP features.For the publish-subsribe pattern,in order to solve the problem that there is no mechanism to support the pattern in HTTP2,while there is an observe mechanism to support the pattern in CoAP,this paper uses cache machanism.Therefore,a HTTP2 endpoint can subscribe the CoAP resources and CoAP resources can be published to the HTTP2 endpoint.The different stages in the publish-subscribe pattern are analyzed based on the characteristics of the two application layer protocols.This paper also provides a detailed description and analysis of the translated content of the converter in the proxy modules.Finally,this paper conducts experiments on the two patterns and the results show that the proposed conversion methods are feasible and usable.