Optimizing MQTT-CoAP Interoperability: A Broker-Based Extension for Seamless Integration

The Internet of Things (IoT) is revolutionizing connectivity by enabling everyday objects and devices to communicate over the Internet, streamlining industrial processes, improving quality of life, and driving innovation across various applications. Ensuring seamless communication between heterogeneous IoT devices remains a fundamental challenge due to differences in underlying communication protocols. This work presents a broker-based extension designed to enable direct, bidirectional interoperability between MQTT and CoAP, two of the most widely adopted IoT protocols. Unlike middleware-based solutions, this approach integrates RESTful and publish/subscribe paradigms within a single broker architecture, streamlining deployment and minimizing system complexity. The proposed solution demonstrates low-latency performance and minimal resource overhead with low median latencies of 2.15 ms and an estimated increase of only 0.53 ms over the baseline. Resource-wise, the broker extension shows a modest median CPU overhead of 2.6% and a memory usage increase of just 0.1% at higher throughputs. These results confirm that the system can efficiently manage multiple concurrent message flows and maintain scalability under varying traffic conditions. This position the broker extension as a practical, modular, and lightweight solution for enhancing IoT interoperability in constrained environments.