An implementation of CoAP-based semantic resource directory in californium

Abstract

Although Resource Directory (RD) is proposed and still under standardization by IETF CoRE WG for resource discovery in constrained networks, Californium as an open-source platform of CoAP is short of the RD functions and could not well support CoAP-based semantic applications to do data analysis and security related to discoveries and allocations. This paper demonstrates an implementation of RD entity with basic mechanisms including URI discovery, resource registration and resource lookup in Californium, and improves the semantic-based resource discovery through adding several sematic attributes such as reference ontology (ro), semantic description (sd) and annotation type (at). The experimental results show that the implementation works are feasible and consistent with CoRE WG's RD specification. Also its performance is given and achieves satisfactory results in semantic application. By realizing the semantic RD functions in Californium, this paper could promote CoAP based on IoT semantic researches on the Californium framework in the future.