OOI Reactive Applicationmust get access to the data in the context of type definition in compliance with the OPC UA Information Model. This article summarizes research on the architecture of infrastructure supporting access to the data using a Message Centric communication pattern. The proposed architecture is presented in the following figure.
OOI Reactive Application- a program application that processes OPC UA Data available out of band, i.e. without the necessity of creating an OPC UA session.
UA Client- a program application that processes OPC UA Data available throughout the created OPC UA session using standard services.
UA Server Services- a typical part of any OPC UA server that provides standard services.
Address Space Management- a typical part of any OPC UA server that manages the nodes in the Address Space.
OOI Reactive Applicationis an application program processing the data in the context of the OPC UA metadata outside the OPC UA server session. In the presented architecture it gets access to the Semantic-Data using the underlying Transport supporting networking services compliant with the Message Centric communication pattern standardized in OPC Unified Architecture Specification Part 14 PubSub. As opposed to OPC UA Session Centric communication the Transport by design is not responsible for distributing type definitions at run time. To realize the UA Semantic Data paradigm, the data sent over the network must, therefore, be decorated with an unique identifier to find the context prepared in advance against the type definition (semantics), e.g. a picture to display the data, an algorithm to calculate new values, a key to encrypt the message payload, etc. For example,
OOI Reactive Applicationmay be any remote mobile device according to the Internet of Things architecture concept, interested in publishing process data using the remote OPC UA server. It's even possible to connect household appliances, sensors and other devices to a central application. For example, it could browse a message broker (Transport) against defined topics, like a definition, that represent data to be published in the OPC UA Address Space. For example, IEC61850-enabled IEDs that get digitalized power grid condition data via process bus and merge units.
Semantic-Datanetworking according to the presented architecture may be recognized as a proof of concept for that standard. Interoperability rules must create a common foundation for: