Integrating OPC UA with web technologies to enhance interoperability

The so-called fourth industrial revolution features the application of modern Information & Communication Technology (ICT) concepts and technologies in industrial contexts to create more flexible and innovative products and services leading to new business models and added value. The emerging Industrial Internet of Things (IIoT) is one of the main results of this revolution. One of the most known and adopted communication protocol in the context of the fourth industrial revolution is OPC UA (IEC 62541). Although this standard already combines features coming from both industrial and ICT contexts, current literature presents several approaches aimed to introduce ICT enhancements into OPC UA in order to further improve its usability in industrial environments. Some of these approaches are based on the proposal to make OPC UA RESTful, due to many advantages of RESTful services in industrial settings. OPC UA is based on a client/server architecture and adopts an information model at the server side, whose access from the client side requires knowledge of a data model, whose structure is sometimes complex, creating some difficulties for a resource-constrained device acting as client. The paper proposes the definition of a web platform able to offer access to OPC UA servers through a REST architecture. The approach presented in the paper differs from other existing solutions, mainly because it allows to realise a lightweight OPC UA RESTful interface reducing the complexity of the basic knowledge to be held by a generic user of the platform. For this reason, the solution presented allows enhancement of OPC UA interoperability towards resource-constrained devices. The web platform has been implemented and the relevant code is available on GitHub.