Bridging OPC UA and DPWS for Industrial SOA
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Two web-service based specifications, OPC Unified Architecture (OPC UA) and Devices Profile for Web Services (DPWS), have been proposed by various researchers and organizations as possible enabling technologies for an event-driven Service Oriented Architecture for monitoring and control in manufacturing applications. This paper aims to propose and demonstrate an approach for bridging these two technologies in a way that is applicable in existing industrial applications. A merger between OPC UA and DPWS that effectively combines their complementary strengths could help pave the path toward future industrial event-driven SOA applications, with the inherent modularity, agility, and interoperability envisioned by researchers today. A representation of DPWS devices, services, operations and events in the OPC UA data model is proposed, and a DPWS Module is developed for Ignition, a commercially available HMI/SCADA and MES platform with integrated OPC UA Server. The module discovers DPWS devices in a local network, creates the representation in the address space, and handles subscriptions, input and output parameter values, and invoking operations. A Complex Event Processing component based on Microsoft’s StreamInsight is also integrated with the system, input and output adapters exposing web service interfaces. The system prototype developed will be used as the base for a use case demonstrator in the European Commission’s Framework Package 7 Project, “Architecture for Service-Oriented Process Monitoring and Control (IMC AESOP).” The project aims to develop a system of systems approach for monitoring and control, based on SOA for very large-scale systems in the process industries.