MQTT Protocol Stack Optimization with Edge–Fog–Cloud Hierarchical Architecture and CoAP Lightweight Alternatives for Graph‐Based IoT Network Communication

The rapid growth of Internet of Things (IoT) devices has created unprecedented demands on messaging infrastructure, with billions of devices generating and transmitting trillions of data points across distributed systems. This chapter examines holistic optimization techniques in the Message Queuing Telemetry Transport (MQTT) protocol stack integrated within a hierarchical edge–fog–cloud architecture, along with an analysis of Constrained Application Protocol (CoAP) as a lightweight alternative for ultra-resource-constrained environments. The integration of MQTT and CoAP within hierarchical edge–fog–cloud architectures presents a promising approach, allowing each protocol to be deployed where it is most effective while accommodating heterogeneous devices and network conditions. The rapid development of IoT technologies has significantly impacted various application domains, including agriculture, smart cities, edge computing and embedded systems. MQTT protocol stack optimization substantially reduced device resource requirements, enabling deployment on severely constrained devices.