Towards Interoperable Industrial Internet of Things An On-Demand Multi-Protocol Translator Service
Abstract: The Industrial Internet of Things (IIoT) is the result of the intersection between advancements in technology and the demand for more efficient and sustainable industry. Technology has provided a means for a large and heterogeneous collection of networks, devices, developers, owners, users and other stakeholders. From this there is a clear need for highly interoperable and independently developed systems. Interoperability is a communication challenge which affects all layers in a system. Communication protocols such as HTTP, CoAP, XMPP, OPC-UA and MQTT are above the network layer and below a semantic layer. This challenge includes overcoming interaction pattern differences, such as session and session-less protocols or publish/subscribe and request/response protocols. Common interoperability methods look at utilizing, a) middleware, such as in-system adapters and protocol gateways or b) restricting protocols to one or two possibilities. However, these solutions do not fit IIoT well as they are costly to adapt as the protocol landscape evolves, are intrusive to design or increase development costs. Service-Oriented Architecture (SOA) has been identified as having a great potential for integrating independent systems. When applied to industrial contexts, SOA late-binding and service composition offers opportunities for enhancing interoperability. However, SOA-based service contracts still require complete agreement between provider and consumer in order to exchange service. In this thesis an approach toward interoperability is proposed which leverages SOA principles and a multi-protocol translator. The proposed approach is first contextualized with a set of requirements pulled from existing literature and from application domain requirements. The thesis asks the question; how can late-binding and service composition be used to support a multi-protocol network of systems? The result, a new approach of a secure, on-demand and transparent protocol translator, is proposed. Conceptually satisfying the requirements defined, the design is backed up with empirical testing on usability and latency of the solution. The proposed solution differs from middleware in that, it is a participant (alongside the application system), it is on-demand (only used when needed), it is not intrusive (no design time dependencies) and it operates transparently (to application systems). A complete interoperability solution is deemed as future work, which could extend to full security, general encoding and semantic interoperability.
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