Functional Size Measurement of IoT Devices using COSMIC Function Point: A Novel Set of Guidelines

The Internet of Things (IoT) envisions a future in which digital and physical elements can be linked using appropriate information and communication technologies to enable a whole new class of applications and services. The paradigm for the IoT is dynamic and continuously evolving. In this paper, we present a COSMIC Function Point (CFP) based approach to address the problem of measuring the functional size of IoT devices for postmortem analysis. We propose a set of mapping guidelines and recommendations, outlining the best practices for using COSMIC Functional Size Measurement (FSM) in quantifying the size of IoT devices developed with ESP8266 System-on-Chip (SoC) using Arduino platform. Guidelines have been established to measure the functional size of an IoT device precisely, which is essential for its maintenance activities such as error corrections, capability enhancements, removal of obsolete features, and performance optimization. Exploring the ESP8266 SoC and Arduino platform, the paper investigates the relationship between the functional size and other system-related technical indicators like Random Access Memory (RAM) usage and code size through use of case studies involving real-world sample IoT prototypes. As a result, we derive RAM usage and code size of IoT devices from their CFP count, leading to invaluable insights. The knowledge acquired from our study therefore contributes to developing a more accurate and efficient method for estimating the functional size of IoT devices. The study also offers relevant information about the application of COSMIC FSM based on software source code, benefiting both academia and industry. Further, we believe this research is an essential step toward increasing the effectiveness of using FSM for the postmortem analysis of IoT devices.