Middleware Architecture for Application Layer Interoperability of Standardized Digital Representations

Platform Industry 4.0 conceptualizes Industry 4.0 as a smart factory that is composed of smart production processes, smart entities and smart products working in tandem to achieve larger goals, namely enabling flexible manufacturing, efficient resource utilization, optimal decision making, catering to individual preferences and creation of new services Smart entities are digital representations of physical or logical objects that can communicate with the external world and take independent decisions.These digital representations can choose different application-layer protocols (ALPs) such as MQTT or HTTP or CoAP for the exchange of messages with the external world. This requires addressing the concept of Application layer interoperability. In this paper, we review the past works by different authors that propose middleware architectures for enabling the exchange of messages in such a multi-protocol environment. Next, we argue for a better alternative and propose new architecture coined as Registry Infrastructure Component (RIC). RIC is a complex software component that maintains a registry, different ALP plugins. The digital representations have to register their ALP endpoint information with the RIC initially and later can post all the outbound messages to any of the RIC ALP plugins. The RIC takes the responsibility of transporting the message to the target recipient. Apart from registration with the RIC, the digital representations would have to communicate only in the I4.0 language.