I have been discussing the importance of industrial protocols to successful use of the Industrial Internet of Things. Among three news releases from the OPC Foundation is news about collaborative work between the Object Management Group (OMG) and OPC Foundation to let DDS and OPC UA play nicely in the same sandbox. This is key because the Industrial Internet Consortium has adopted DDS as a standard, while much of the industrial automation community uses OPC.
Other news includes the announcement of support for publish/subscribe for OPC UA and an OPC UA open source initiative.
Industrial Protocol Collaboration
Specifically, the OPC Foundation and OMG have developed a technical positioning and FAQ document for usage of both the OPC Unified Architecture (OPC UA) and the OMG Data Distribution Service (DDS) standard. The positioning document explains that the OPC UA and DDS standards are largely complementary and compatible. Both are important to the future of the IIoT. The document is a joint recommendation; it helps companies quickly implement an IIoT strategy.
OPC UA and DDS Explained
OPC UA is an industrial communication architecture for platform independent, high performance, secure, reliable, and semantic interoperability between sensors, field devices, controllers, and applications at the shop-floor level in real-time as well as between the shop floor and the enterprise IT cloud. OPC UA allows SoA based easy “plug and produce” scenarios. The information about the system, its configuration, topology, and data context (the meta data) are exposed in the collective “address space” of the individual OPC UA servers.
This data can be accessed by authorized OPC UA clients that can see what is available, and choose what to access. OPC UA truly supports timeless durability as new networking technology is developed it can be plugged into OPC UA seamlessly. Client/Server, Pub/Sub and cloud protocols are integrated into OPC UA.
DDS provides location transparent, interoperable, secure, platform independent, real-time data sharing across any kind of network. DDS lets applications define and share user data with controlled “Quality of Service” (QoS) such as performance, scalability, reliability, durability and security. DDS hides network topology and connectivity details from the application, providing a simple yet powerful data-sharing abstraction that scales from local area networks to fog and cloud computing. It can support even large fan out and sub-millisecond latency. DDS defines a “common data-centric information model” so that applications can run “plug & play” with very little or no deployment configuration. System configuration details are deemphasized to ease redundancy and interoperability.
Today, there is little overlap between OPC UA and DDS in applications. Even when used in the same market (e.g. energy) the use cases are quite different. Today OPC UA provides client-server interaction between components such as devices or applications. DDS is a data-centric “bus” for integration and peer-to-peer data distribution. Because the focal applications and approaches for DDS and OPC UA are different, most applications clearly fit better with one or the other.
The OPC Foundation and OMG are working together on integration and have developed two ways for the technologies to work together. First, an “OPC UA/DDS gateway” will permit independent implementations to work together. Second, “OPC UA DDS Profile” will enable integrated use cases. Initial work to define both approaches is underway at the two standards organizations.
Customers must choose a standard path now to implement a successful IIoT strategy. By working together, the OPC UA and DDS communities will provide a non-proprietary path to interoperability, regardless of the customer’s choice of starting technology.
Open Source OPC UA
The open source repository of OPC UA is now available on the open source GitHub web site. Open source is a very important strategy to eliminate roadblocks to adoption of the technology. By open sourcing the OPC UA technology the OPC Foundation is now enabling easy access to the technology by academia and research organizations, as well as many suppliers and end-users that would like to assess the OPC UA technology as part of early adopter and feasibility analysis.
Open sourcing isn’t just the wave of the future. Open source strategy is now. The OPC Foundation is proud to make the OPC technology available to everyone via the open source repositories.
There are a number of OPC open-source initiatives already available from suppliers, research institutes and academia for OPC UA. The open source repository from the OPC Foundation is intended to supplement these other open-source initiatives, providing additional value. The OPC Foundation has committed resources to moderate/maintain and extend the technology to keep pace with technology changes in the industry as well as the extensions to the OPC UA architecture and corresponding companion specification.
Publish Subscribe
The OPC Foundation addition of publish/subscribe communication functionality to OPC UA provides the necessary infrastructure to achieve seamless interoperability for IIoT, IoT, and industrie 4.0 applications and devices. OPC has been based on a client/server architecture, and is now enhancing the architecture with the inclusion of publish/subscribe to provide a solid infrastructure that allows information integration from embedded devices to the cloud.
The OPC Foundation is working currently with 42 international (and many more to be added) suppliers that are developing products and solutions for the IIoT and needed to provide publish/subscribe to the technology portfolio to facilitate high-performance high reliable device application connectivity for this important market. Support for publish/subscribe as well as the client/server architecture provides a complete solution for any device or application. Existing applications already using OPC UA client/server communications can add the publish/subscribe features with minimal effort.
A demonstration of the OPC UA publish/subscribe functionality will be held at Hanover Fair the week of April 25 in the OPC Foundation Booth hall 9 – A11. This demonstration will consist of multiple vendors showing OPC UA enhanced with publish/subscribe, truly demonstrating how easy it is to have connectivity and information integration in IoT devices and applications. The demonstration will show both semantic and syntactic data interoperability.
