Comparison of communication technologies for industrial middlewares and DDS-based realization

The automation industry is currently in the process of transforming towards Industrie 4.0. To fully leverage the new possibilities, e.g., predictive maintenance, systems from all levels of the AT-pyramid are required to be fully connected. For this purpose there exist abstract models as well as concrete implementations of middleware-based interconnection platforms. This paper aims to close the gap between abstract concepts and concrete implementations by comparing technological concepts for a middleware implementation. At first, requirements are determined, which should be fulfilled by middleware to be comprehensible and competitive. Based on these requirements, six different middleware technologies are presented and evaluated. The evaluation yields that both OPC UA Pub/Sub with AMQP/MQTT as transport and DDS suit the requirements best. However, there are no complete implementations of OPC UA Pub/Sub with AMQP/MQTT as transport available yet. Therefore DDS is chosen for a prototypical middleware implementation. The prototype is tested and shows to fulfill all except one requirement, namely real-time constraints. In conclusion, it is recorded that for future middleware implementations, OPC UA Pub/Sub (as soon as complete implementations are available) and DDS are the most appropriate technologies.