Analysis and Classification of Service Interactions for the Scalability of the Internet of Things Damian Arellanes and Kung-Kiu Lau School of Computer Science The University of Manchester Manchester M13 9PL, United Kingdom {damian.arellanesmolina, kung-kiu.lau}@manchester.ac.uk Abstract: Scalability is an important concern for Internet of Things (IoT) applications since the amount of service interactions may become overwhelming, due to the huge number of interconnected nodes. In this paper, we present an IoT scenario for real-time Electrocardiogram (ECG) monitoring, in order to analyze how well different kinds of service interactions can fulfill the scalability requirements of IoT applications.