Which IoT protocol? Comparing standardized approaches over a common M2M applicationWhich IoT protocol? Comparing standardized approaches over a common M2M application Πλήρης Δημοσίευση σε Συνέδριο Conference Full Paper 2018-11-222016enComputing devices already permeate working and living environments, while researchers and engineers aim to exploit the potential of pervasive systems in order to introduce new types of services and address inveterate and emerging problems. This process will lead us eventually to the era of urban computing and the Internet of Things (IoT). However, the long-promised improvements require overcoming some significant obstacles introduced by these technological advancements. One such obstacle is the lack of interoperable solutions, to facilitate the use, monitoring and management of the plethora of devices and their services. While seamless machine-to-machine (M2M) and human-to-machine (H2M) interactions are a necessity for secure and truly ubiquitous computing, the current status quo is that of a segregated and incompatible assortment of devices. The resource-constraints of the platforms integrated into smart environments, and their heterogeneity in hardware, network and overlaying technologies, only exacerbate these interoperability issues. Motivated by the above, this paper identifies three promising, standardized protocols, each following a different approach in addressing the above concerns. We evaluate the selected protocols in the context of designing and implementing an application requiring various M2M interactions, namely a policy-based access control framework for IoT devices. Thus, three variants of the application are developed, considering each protocol's intrinsic characteristics and features. Finally, the developed applications are evaluated on a common testbed of embedded devices, allowing us to extract useful conclusions concerning the protocols' performance, their intricacies and their applicability in similar applications.http://creativecommons.org/licenses/by/4.0/59th IEEE Global Communications Conference2016 IEEE Global Communications Conference, GLOBECOM 2016 - Proceedings2016 Fysarakis Konstantinos Φυσαρακης Κωνσταντινος Askoxylakis, Ioannis Soultatos Othonas Papaefstathiou Ioannis Παπαευσταθιου Ιωαννης Manifavas Charalabos Μανιφαβας Χαραλαμπος Katos, Vasilis Institute of Electrical and Electronics Engineers Authorisation Embedded systems IoT Internet of Things Open systems Protocols