OPC UA and MQTT performance analysis within a unified namespace context

Abstract

One of the main obstacles to fully adopting and implementing Industry 4.0 concept and achieving effective digital transformation is interoperability. Various communication protocols, aligned with different architectures, present themselves as potential solutions. The Unified Namespace (UNS) has emerged as a promising approach for data-centric architectures aligned with reference frameworks like Reference Architectural Model Industrie 4.0 (RAMI 4.0) and The Industrial Internet Reference Architecture (IIRA). Open Platform Communications Unified Architecture (OPC UA) and Message Queuing Telemetry Transport (MQTT) are among the most widely used communication protocols applicable in a UNS. Determining which of these is most suitable for specific applications requires further exploration. This paper provides an in-depth comparison of these protocols across several key Industry 4.0 metrics, based on data from an industrial-like case study and qualitative insights from the research team. Findings indicate that a lightweight protocol like MQTT offers advantages in raw performance metrics in its efficiency and scalability; however, depending on the application and organizational philosophy, OPC UA may offer a more comprehensive solution, mainly in terms of security and interoperability. The study’s results are limited by reliance on a single case study and lack of failure or cyber-attack scenarios. Future work will expand testing with more clients, simulate network faults and attacks, and include OPC UA Pub/Sub for broader comparison.