Observing Resources in the Constrained Application Protocol (CoAP)
Klaus S. Hartke · 2015
The Constrained Application Protocol (CoAP) is a RESTful application protocol for constrained nodes and networks.The state of a resource on a CoAP server can change over time.This document specifies a simple protocol extension for CoAP that enables CoAP clients to "observe" resources, i.e., to retrieve a representation of a resource and keep this representation updated by the server over a period of time.The protocol follows a best-effort approach for sending new representations to clients and provides eventual consistency between the state observed by each client and the actual resource state at the server.