This project consists in the development of a CoAP Proxy for Resource Observing (node temperature sensor) on IoT Contiki nodes simulated in the Cooja enviroment. Contiki nodes are programmed in C while the CoAP Proxy and the Client are programmed in Java Californium. See the documentation for details on how to run. This project was developed for the Advanced Networks & Wireless Systems course (MsC in Computer Engineering @ University of Pisa) in collaboration with G. Alvaro and L. Fontanelli.