DDS provides a real-time, scalable, and reliable data exchange for connected systems. It also allows for the automatic discovery of devices and applications. It also supports multiple quality of service (QoS) settings.

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Real-time data distribution

Real-time data usage continues to grow as an expanding array of applications rely on up-to-the-second information. To ensure that this information is delivered reliably and quickly, a high-performance communication protocol is required. The Data Distribution Service (DDS) is a software connectivity standard that provides the critical data communication functionality required for real-time distributed systems.

DDS is a broker-less, peer-to-peer communication architecture that provides extreme reliability and massive scalability to meet real time system requirements. It also supports a variety of QoS behavioral settings that are specific to your application use cases.

While the DDS standard does not specifically outline security features, RTI’s Connext DDS middleware offers a comprehensive set of security features including process separation via MILS; event authentication and confidentiality; inter-domain bridging and secure routing; and content-based filtering (RTI, 2013). This allows you to ensure that your critical data is protected across your distributed systems. This also helps prevent the transmission of unnecessary data, which can reduce WAN costs and improve performance.

Scalability

DDS supports the publish-subscribe pattern, allowing applications to send requests and track responses from multiple nodes simultaneously. The system also offers efficiency via multicast or unicast delivery and the ability to track responses from independent nodes in the same way.

DDS is particularly suited for UAS as it can handle massively parallel communication, even over lossy or intermittent RF and satellite transports. Moreover, DDS does not depend on a central server or broker, which eliminates the single point of failure and imposes no chokepoint from a performance perspective.

DDS can deliver real-time data over the Internet or intranet without sacrificing consistency, availability, fault-tolerance, or scalability. Its underlying architecture supports the use of partitioned persistent data structures, enabling DDS to scale to the size of an entire network. In addition, DDS supports a range of QoS policy settings, including deadlines, latency budgets, and access behaviors. This enables the system to ensure that critical data stays localized while non-critical data is transported across the WAN.

Fault-tolerance

Fault tolerance is an important component of distributed systems, allowing them to continue operating despite the failure of a single system component. It can also reduce the time it takes to detect and repair a fault, improving overall performance. Fault-tolerant systems often use redundancy, which involves having duplicate copies of key components such as power supplies and disk drives.

The term “fault tolerance” is often mistaken for redundancy, although there are some differences between the two. For instance, a fault-tolerant system may have redundant processors, while a redundancy-based approach only provides backup processors in case of failure.

Some systems use a combination of both techniques to achieve fault tolerance. For example, a system with multiple processors could implement both hardware redundancy and software error-correcting algorithms. Another method is to use a recovery block technique, which is similar to n-version programming but uses different algorithms for each copy of data. This approach is useful in applications where timeliness or QoS performance is more important than data consistency.

Security

Today’s mission-critical Industrial Internet of Things (IIoT) systems derive tremendous benefit from their connectivity, but these additional network connections expose them to new security risks. The OMG’s DDS standard provides a state-of-the-art, open publish-subscribe data connectivity solution that addresses these security concerns through its security plugin API’s.

The DDS Security specification contains several plugins to address different security aspects: Authentication, Access Control and Cryptographic. Each plugin supports a set of standardized Service Plugin Interface (SPI) implementations to ensure a baseline level of functionality and interoperability between DDS implementations.

The Authentication plugin offers protection against unauthorized subscription to Topic T by requiring that only authorized DataReaders be able to subscribe. It also verifies that the DDS entity associated with the triggering PSR is using a specific subset of data tags. DDS security can also protect against eavesdropping by ensuring that only authorized DataReaders can make sense of data published to Topic T. In addition, it can prevent unintentional republishing of data to a public audience by enforcing access control on the published data.