Implement CoAP (Conditional-)Observe in Wiselib

by Philipp Abraham for The Wiselib

CoAP is a RESTful application protocol for constrained nodes and networks. Resources (containing sensor informations) on a CoAP Server can change their state over time. To keep clients updated with the latest values the "CoAP Observe" extension has been proposed. In order to minimize the amount of data sent over the network, a client could also register for notifications of certain changes only (e.g. "notify me whenever the luminance changes drastically" ). For these scenarios, the "conditional observe" extension to CoAP is being developed. My proposal would be to extend the current CoAP implementation for Wiselib to support the "observe" and "conditional observe" extensions. Additionally I would try to implement the upcoming draft of high level states which enables a client to create resources with special names for ranges of values (e.g. "hot" for values between 30°C - 40°C).