RTI Data Distribution Service

RTI Data Distribution Service is communications middleware for distributed real-time applications. It is the most reliable, flexible and highest-performing implementation of Object Management Group's (OMG) Data Distribution Service standard available today. RTI Data Distribution Service is field proven and is used in many time-critical and data-critical application such as financial transaction processing, national railways, air traffic control, traffic monitoring, combat systems and industrial automation.

What's New in 4.2?: RTI's latest version of RTI Data Distribution Service offers several exciting new features and product improvements, including secure data exchange over WANs, data persistence, support for the DDS interoperability protocol, improved discovery performance, and support for additional platforms. Learn more...

How It Works

RTI Data Distribution Service is networking "middleware" that simplifies complex network programming. It implements a publish-subscribe model for sending and receiving data, events, and commands among the nodes. Nodes that are producing information (publishers) create "topics" (e.g., temperature, location, pressure) and publish "samples." RTI Data Distribution Service delivers the sample to all subscribers that declare an interest in that topic.

RTI Data Distribution Service handles all the transfer chores: message addressing, data marshaling and demarshalling (so subscribers can be on different platforms than the publisher), delivery, flow control, retries, etc. Any node can be a publisher, subscriber, or both simultaneously.

The RTI Data Distribution Service publish-subscribe model virtually eliminates complex network programming for distributed applications.

RTI Data Distribution Service supports mechanisms that go beyond the basic publish-subscribe model. The key benefit is that applications that use RTI Data Distribution Service for their communications are entirely decoupled. Very little design time has to be spent on how to handle their mutual interactions. In particular, the applications never need information about the other participating applications, including their existence or locations. RTI Data Distribution Service automatically handles all aspects of message delivery, without requiring any intervention from the user applications, including:

determining who should receive the messages,
where recipients are located,
what happens if messages cannot be delivered.

This is made possible by the fact that RTI Data Distribution Service allows the user to specify Quality of Service (QoS) parameters as a way to configure automatic-discovery mechanisms and specify the behavior used when sending and receiving messages. The mechanisms are configured up-front and require no further effort on the user's part. By exchanging messages in a completely anonymous manner, RTI Data Distribution Service greatly simplifies distributed application design and encourages modular, well-structured programs.

RTI Data Distribution Service also automatically handles hot-swapping redundant publishers if the primary fails. Subscribers always get the sample with the highest priority whose data is still valid (that is, whose publisher-specified validity period has not expired). It automatically switches back to the primary when it recovers, too. RTI Data Distribution Service is available with C, C++, and Java APIs.

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Real-time delivery over IP?

RTI Data Distribution Service provides fast, deterministic data delivery over standard IP. This allows developers to use low-cost, off-the-shelf Ethernet components to distribute high frequency, periodic data (we refer to it as "streaming" data) within strict timing constraints. This greatly simplifies the integration and management of real-time systems alongside other enterprise networked systems.

Pluggable Transport Interface: RTI Data Distribution Service comes with a standard UDP/IP pluggable transport and a shared memory transport. It can also be configured to operate over a variety of other transport mechanisms, including backplanes, switched fabrics, and new networking technologies.

RTI Data Distribution Service is optimized to add minimal latency to the network communications overhead. In addition, RTI Data Distribution Service lets the developer specify Quality of Service parameters such as deadline on a subscription-by-subscription basis. If a data sample is not received by the deadline, RTI Data Distribution Service notifies the application immediately to preserve its deterministic behavior. This also allows the developer to manage data flow according to the needs and capabilities of each subscriber on the network individually.

RTI Data Distribution Service is a good real-time partner for embedded applications too. It has a small footprint and memory is carefully managed to preclude ad hoc memory allocation requests and memory fragmentation. RTI Data Distribution Service also protects the application's real-time threads from network anomalies and untimely interrupts.

But that's not all you get. Distributed, real-time applications require more than getting streaming data from the publisher to multiple subscribers. For example, the subscriber application must be able to handle asynchronous alarms from the publisher quickly and efficiently, subscribers often need to talk directly to a publisher to get status, and a network manager might need to send commands directly to publishers and subscribers alike.

RTI Data Distribution Service implements the Data-Centric Publish-Subscribe (DCPS) API within the OMG’s Data Distribution Service (DDS) for Real-Time Systems standard. DDS is the first standard developed for the needs of real-time systems. DCPS provides an efficient way to transfer data in a distributed system.

With RTI Data Distribution Service, systems designers and programmers start with a fault-tolerant and flexible communications infrastructure that will work over a wide variety of computer hardware, operating systems, languages, and networking transport protocols. RTI Data Distribution Service is highly configurable so programmers can adapt it to meet the application’s specific communication requirements.

RTI Data Distribution Service features that help developers with distributed real-time application design, development and deployment include:

Reliable communications mode assures that a subscriber gets every data sample in order: an essential feature for alarms and commands.
Ownership strength and liveliness duration QoS provide application-transparent hot swap for redundant data writers. The developer assigns each data writer an ownership strength and liveliness duration. For any requested topic, RTI Data Distribution Service returns the data from the highest strength data writer that's still considered ‘alive.’
Multicast addressing minimizes bandwidth use for big distributions and/or large packets.
Multiple QoS for adjusting latency, thread timing, and network bandwidth requirements.
Redundant network support.
No single point of failure.
Dynamic, real-time reconfiguration as applications join and leave the network.

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What's the right middleware for your application?

The publish-subscribe model beats client-server hands down when you need to distribute data broadly. Several vendors provide middleware products that have dramatically simplified enterprise and Internet application development. In many cases RTI Data Distribution Service is a cheaper, lower-latency alternative to the enterprise solutions even in these applications. RTI Data Distribution Service is the best publish-subscribe middleware for distributed real-time applications because it is:

deterministic subscriptions
small footprint and overall memory requirements
real-time thread and memory protection
support for the most popular embedded platforms

RTI Data Distribution Service middleware is designed to minimize latency, too.

Publish-subscribe is capable of supporting one-to-many connectivity along with redundant Publishers and Subscribers. This feature is ideal for constructing fault-tolerant or high-availability applications with redundant nodes and robust fault detection and handling services.

Publish-subscribe is ideal for building reconfigurable applications with many participating nodes. This helps real-time system developers more easily handle dynamic, ad-hoc, and intermittent networks, like wireless.

Publish-subscribe maps well to connectionless protocols. For instance, publish-subscribe can take advantage of multicast technology to efficiently send real-time data to many subscribers. The use of connectionless protocols like UDP and multicast enables real-time systems to scale up higher than with connection-oriented (point-to-point) protocols like TCP.

How does DDS compare to CORBA and DCOM?

CORBA and DCOM implement distributed objects using a client-server communications model. Many real-time applications are data-centric, that is, the applications require data distribution, not remote service invocations or function calls.

Publish-subscribe is more efficient than client-server in both latency and bandwidth for periodic data exchange. Publish-subscribe drastically reduces the overhead required to send data over the network compared to a client-server architecture. Occasional subscription requests, at low bandwidth, replace numerous high-bandwidth client requests. Latency is also reduced, since the outgoing request message time is eliminated. As soon as a new publication data sample becomes available, it is sent to the corresponding subscriptions. Learn about integrated CORBA and DDS solutions...

Case Studies

US Navy

Open Architecture Computing Environment specifies RTI Data Distribution Service (PDF)
The Navy’s Open Architecture Computing Environment (OACE) recommends the DDS publish-subscribe standard and specifically refers to RTI Data Distribution Service.

Tactical Communications Group

TCG enhances their Tactical Communications Manager (TCM) (PDF)
The Tactical Communications Manager (TCM) integrates digital datalinks into weapons, command and control (C2) and surveillance systems. RTI Data Distribution Service delivers the high-performance, scalability, and reliable communications required for this application.

Lockheed Martin

Lockheed Sea SLICE™ uses RTI Data Distribution Service (PDF)
Lockheed Martin’s SLICE™ technology is a ship design that allows ships to operate at higher speeds without sacrificing efficiency. It uses RTI Data Distribution Service for the inter-processor communications that keep the ship stable in high seas.

University of Iowa and US Army

National Advanced Driving Simulator and Simulation Center (PDF)
Researchers from the University of Iowa National Advanced Driving Simulator and Simulation Center (NADS-SC) and the US Army TACOM-TARDEC Ground Vehicle Simulation Laboratory (GVSL) connected several high-fidelity simulators to test and evaluate US Army vehicles. They chose RTI Data Distribution Service to connect the simulator sites. Read why RTI Data Distribution Service was vital to this project’s success.

Bluefin Robotics

Bluefin Robotics chooses RTI Data Distribution Service (PDF)
Discover why Bluefin Robotics selected the real-time performance of RTI Data Distribution Service for its innovative Bluefin 9 unmanned underwater vehicle.

Georgia Tech

Georgia Tech UAV Research Facility (PDF)
Find out how a team from Georgia Tech’s UAV Research Facility took RTI Data Distribution Service off the shelf and into the air during the 2000 International Aerial Robotics Competition.

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Overview & What's New