Connectivity Framework
7: Connectivity Standards
Similar to the way a database controls access to stored data, a databus controls data access and updates by many simultaneous components. At its core, DDS is built around a data-centric publish-subscribe data exchange pattern. However, the standard also defines a request-reply data exchange pattern, and vendors offer queuing. The key abstraction is that applications interact with the databus itself, not directly with other applications participating in that interaction. DDS offers precise data-centric quality-of-service( QoS) control, reliable multicast, configurable delivery, multiple levels of data durability, history, component and transport redundancy, automatic discovery, connectivity management, and transport agnostic fine-grained data-centric security. In addition, one-to-many and many-to-one communications is a key strength. DDS offers powerful ways to filter and select exactly which data goes where, and“ where” can be thousands of simultaneous components. To support small, edge devices, there are lightweight versions of DDS that run in constrained environments. The DDS databus ensures ultra-reliable operation and simplifies application code. It does not require servers, greatly easing configuration and operations while eliminating failure and choke points.
A DDS-based system has no hard-coded interactions between components. The DDS databus automatically discovers and connects publishing and subscribing components. No configuration changes are required to add new components( e. g. a smart machine) to a system. Components can be developed or sourced from independent parties. DDS overcomes problems associated with point-to-point system integration, such as lack of scalability, interoperability and the ability to evolve the architecture. It enables plug-and-play simplicity, scalability and exceptionally high real-time performance.
DDS is commonly used for system integration and for building autonomous systems, because of the flexibility, reliability and speed necessary to build complex or real-time applications. DDS is a proven technology for reliable, high performance, large-scale IIoT software systems across many vertical industries. IIoT applications using DDS include wind farms, hospital integration, medical imaging, autonomous planes and cars, rail, asset tracking, automotive testing, smart cities, communications, data center switches, video sharing, consumer electronics, oil & gas drilling, ships, avionics, broadcast television, air traffic control, SCADA, robotics and defense.
DDS Gateways exist for many other connectivity technologies, including DNP3, C37.118, Modbus, HLA, JMS and so on. The DDS-Web v1.0 specification 1 defines a standardized gateway for Web Services. A standard for a gateway between OPC-UA and DDS is underway at the OMG. The OPC Foundation is developing an OPC-UA-DDS pubsub profile 2 with the goal of adding DDS as an additional publish-subscribe communication option to OPC-UA. Work is underway at oneM2M, investigating an interworking gateway between oneM2M and DDS, a DDS protocol binding for oneM2M, and DDS based direct exchange of data between oneM2M entities 3.
1
See [ OMG-DDSWEB ]
2
See [ OPC-DDS ]
3
See [ ONEM2M-27 ]
IIC: PUB: G5: V1.0: PB: 20170228- 48-