Understanding the software framework that connects the industrial IoT

Connecting people anytime, anywhere was the challenge that drove the build-out of the Internet. It revolutionised how people communicate, what they do and how they work together. The Internet continues to evolve so that it can also connect millions of devices, including the diverse components of mission-critical, highly distributed systems. The machine-to-machine (M2M) revolution has imposed much more stringent connectivity requirements for the Industrial Internet of Things (IIoT).

The Data Distribution Service (DDS), an open standard managed by the Object Management Group, was pioneered to specifically address these requirements. DDS implementations have raised the bar for real time connectivity within global networks.

What System Requirements Call for DDS?
A survey of system designers and architects who have already adopted RTI Connext DDS underscores the capabilities addressed by the DDS standard. When asked what led them to DDS, the vast majority includes at least three of the following requirements in their answers:

1. Real time performance: Systems must be able to respond to critical stimuli within a few milliseconds or possibly even microseconds
2. Reliability: Systems suffer severe consequences from any down time in excess of a few seconds, or even fractions of a second (as little as 5ms)
3. Scalability: Ten or more applications, subsystems or teams must be continually connected
4. Support for large data sets: The system utilises 1,000 to 100,000 data points
5. Distributed architecture: The system is targeted for the next-gen IIoT

While a variety of other connectivity protocols can address one or two of these categories, DDS is the only solution that meets the stringent requirements of all five.

How does Connext DDS meet these requirements?
RTI Connext DDS connectivity framework enables developers and system architects to introduce a simple publish-subscribe, data centric connectivity model on top of existing networks. It gives all system components the combination of low latency connections, extreme reliability and the scalability required for today’s complex systems and networks. The adoption of the elegant DDS connectivity architecture reduces both design and integration time with results proven across diverse industries and applications.

Simplified architectures and integration
Connext DDS unburdens the application layer from much of the communication complexity including: data wire format, device discovery, establishing and managing connections, ensuring reliability, intelligently minimising overhead, supporting diverse protocols and creating the desired levels for quality of service. All data management and data distribution logic resides within the decentralised middleware layer, creating a single system-wide source of state information completely separated from the application modules.

Besides the many benefits of decoupling applications and system modules (e.g., reduced application code size, ease of adding new devices), DDS connectivity completely shields the application layer from the highly dynamic and complex underlying network transports and protocols. RTI offers a pluggable protocol interface, with many options for flexibly connecting to custom protocols and network interfaces. 

Low-Latency Connections
In the IIoT, connectivity is all about efficiently sharing and organising the exploding volume of data from sensors and other devices. DDS is data centric, with all communications carried out peer to peer and without requiring data to be brokered by a server or cloud. Instead, the software creates virtual global data spaces, in which authorised data publishers and subscribers can share thousands of data items in what appears to be local memory. DDS organises data by topics and each topic can be configured for the required QoS. In this manner, DDS optimally manages data in motion and allows sharing between embedded, mobile, fog and cloud applications across any transport - with extremely low latency.

DDS also supports automatic discovery of both publishers and subscribers, making it easy to extend systems by connecting new devices and applications and greatly simplifying administration. Devices and applications are automatically discovered at runtime for true plug-and-play and the software also supports run-time data type extensions and can discover and manage QoS settings during runtime.

This data centric approach differs greatly from lower-level messaging protocols such as MQTT, CoAP and AMQP where programmers must write code that controls message flows and manages data before it is sent and after it is received. Instead, the DDS data centric approach creates a controlled, managed, secure data domain. Developers simply configure how and when data is to be shared, with DDS directly implementing and optimising the runtime data sharing.

Flexible quality of service
Powerful and configurable QoS capabilities make it possible for DDS data sharing to maximise reliability, system health and security. To optimise performance across a wide range of networking technologies ranging from low bandwidth, unreliable connections to high speed, low latency interconnects, the RTI QoS implementation offers:

• Intelligent transmissions - sending only the data required by each endpoint
• Configurable reliability parameters - addressing high-priority data or slow unreliable networks
• Automatic change management - including change notification to impacted participants
• Filtering algorithms - optimising transmission and broad distribution of huge data sets
• Multicasting - speeding updates to numerous endpoints
• Version management - including automatic data translations for various parts of the system
• Numerous security features - controlling access, enforcing data flow paths and encrypting sensitive data on the fly

Because of its QoS support, DDS is the only connectivity standard that spans the entire IIoT from connecting devices in the field all the way to collecting data back into the cloud. The alternative is to use a set of point solutions with the added complexity of now having to manage and integrate these different technologies.

Inherent scalability and adaptability
Current RTI Connext DDS deployments are meeting the connectivity needs for small devices, cloud architectures, fog computing and very large systems. High volume data sharing inherently scales across the various endpoints and networks, and delivers predictable performance for thousands or millions of participants. Data is delivered at predictable high speeds, even within systems that manage many thousands of data points.

What do you get with Connext DDS Professional?
RTI Connext DDS connectivity framework is the top-ranked solution for controlled, managed and secure data sharing across a broad range of Internet transports and vertical markets. The customer base spans more than 1,000 system designs, and another 350+ projects in university and research environments. By advancing the DDS industry standard as a member of the Object Management Group, RTI has been able to deliver a solution that fosters interoperability and open architectures for greatly reduced system lifecycle costs.

Connext DDS supports more than 70 platforms and all leading operating systems and includes:

• Connectivity libraries that simplify distributed application development with high level APIs for publish-subscribe, request-reply and point-to-point queues
• A customisable interface adapter framework, simplifying the integration of devices and existing applications (without requiring modification of application code)
• Developer tools for integration, testing and debugging
• Application-specific code examples