Object-Oriented Internet Makes OPC UA PubSub to Cloud Interoperability Possible

Key words

Azure, Cloud Computing, Object-Oriented Internet, OPC Unified Architecture, Reactive Networking (RxNetworking), Machine to Machine Communication, Internet of Things

Abstract

Optimization of the industrial processes requires further research on machine-centric systems with human-centric cloud-based services integration in the context of new emerging disciplines, namely Industry 4.0 and Industrial Internet of Things. This solution aims at working out a new generic architecture and deployment scenario applicable to this integration.

To deal with the network traffic propagation asymmetry or assets’ mobility the reactive interoperability relationship of the interconnected nodes is proposed.

The research in this respect is conducted in the supervisory project: Object-Oriented Internet.

The final solution based on the OPC Unified Architecture PubSub international standard relaxes issues related to the real-time multi-vendor environment. The discussion addressing the generic architecture concludes that the embedded gateway archetype best suits all requirements. To promote separation of concerns and reusability, the proposed architecture of the embedded gateway archetype has been implemented as a composable part of an existing OPC UA PubSub framework available as the NuGet package. This package is an outcome of an open-access project called Object-Oriented Internet maintained on GitHub.

The proposals are backed by proof of concept reference implementations confirming the possibility to integrate selected cloud services with the cyber-physical system interconnected as one whole atop of the OPC UA PubSub in contrast to interconnecting cloud services with a selected OPC UA server limiting the PubSub role to data export only. The outcome has been just published on GitHub as the open-source (MIT licensed) project AzureGateway.

Object-Oriented Internet 6.2.1

To promote interoperability and address the demands of the M2M communication in the context of a multi-vendor environment the prototyping should use a framework that must be compliant with the OPC UA Part 14 PubSub and support the Reactive Interoperability concept. A framework compliant with these requirements has been implemented as an open-source library named UAOOI.Networking under an umbrella of the project Object-Oriented Internet. The library is designed to be a foundation for developing application programs that are taking part in a message-centric communication pattern and interconnected using the reactive networking concept. The Reactive Application is an aggregation of parts implementing the Producer and Consumer roles. By design, they support access to real-time process data, hence they are recognized as an extension of DataRepository class. To get more on how to implement the DataRepository check out the document Azure Gateway DataRepository Implementation – Open Source Project. A more in-depth description of the OOI Reactive Application library enabling data exchange over a network using the reactive networking pattern is covered by the Reactive Networking of Semantic-Data Library.

How to get started

To get the full story and receive your copy, check out the preprint from Research Gateway: Object-Oriented Internet – Azure Interoperability. It is a preprint for early review. We will consider your contribution to be applied to the final version of the article. The paper describes a proof of concept that it is possible to integrate selected cloud services (e.g. Azure) with the Cyber-physical network atop on the OPC UA PubSub applying the proposed architecture and deployment scenario. In contrast to limiting the PubSub role to export the data from the Address Space exposed by a selected OPC UA server, applying the proposed solution enables interoperability of the cloud services and the Cyber-physical network as one whole.

To start prototyping on deployment check out the open-source library: Azure Gateway DataRepository Implementation – Open Source Project.

Conclusion

The described results prove that the embedded gateway archetype implementation is possible based on the existing standalone framework supporting reactive interoperability atop of the M2M communication compliant with the OPC UA PubSub standard. It is worth stressing that there is no dependency on the Client/Server session-oriented relationship. This relationship is in contrast to the architecture described in the OPC UA Part 1 specification where the publisher role is tightly coupled with the Address Space embedded component of the OPC UA Server. In the proposed approach the cloud interoperability is obtained by implementing a dedicated part employing out-of-band communication only without dependency on the OPC UA functionality at all. It is worth stressing that the gateway functionality is implemented as a part – composable to the whole without programming skills. Because the part is composed at the runtime it makes it possible to modify its functionality later after releasing the library or even deploying the application program in the production environment.

See also

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