Electronic Design
Data Distribution Service Scales From Embedded To The Enterprise

Data Distribution Service Scales From Embedded To The Enterprise

Real-Time Innovations' (RTI) Connext 5.0 is an enterprise class real-time Data Distribution Service (DDS) that is compatible with the Object Management Group's (OMG) publish/subscribe interface. RTI has been delivering DDS support for a number of years (see Fast Publish-Subscribe Environment Scales From Micros To Enterprise). Connext 5.0 adds a range of new features including a graphical administration console (Fig. 1).

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Figure 1. The Connext 5.0 administration console provides real time information about the network and nodes.

RTI's Connext 5.0 encompasses a range of tools starting with the central RTI Connext Messaging and RTI Connext DDS. RTI Connext Messaging provides the base publish/subscribe services. RTI Connext DDS provides the data-centric messaging support and it is compatible with the OMG standard. Resource constrained, small footprint systems can employ RTI Connext Micro. These have been certified for a range of applications including DO-178B.

Enterprise developers can utilize the RTI Connext Integrator. It allows bridging between Connext and enterprise Service Oriented Architecture (SOA) systems. The RTI Connext Tools, including the administration console, provide system management and debug support (Fig. 2).

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Figure 2. The Connext Tools can provide real time debug information about the system status.

RTI has enhanced system scalability with a number of new features including optimized, writer-side filtering. It supports an unlimited number of readers with an optimized network protocol that is compatible with DDS. Systems can easily support 1000s of clients.

Publish/subscribe is a useful paradigm for many programming applications but approaches such as remote procedure calls (RPC) is another. Connext 5.0 bridges the gap by extending its feature set beyond DDS. The request/reply support and guaranteed messaging (Fig. 3) are two integration patterns now supported by Connext 5.0. This eliminates the need to simulate them using publish/subscribe. It provides a more efficient and more reliable mechanism as well as one that can be managed better since it is a standard part of the framework.

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Figure 3. RTI has extended its interface beyond DDS publish/subscribe to include programming patterns like request/reply and guaranteed messaging.

DDS and Connext is used on a wide array of commercial and military projects. The UAV Control Software (UCS) is based on DDS. The US Army's VICTORY platform supports DDS.

One reason Connext is used in these demanding environments is that it handles problems like transient connections much better than other networking approaches. Systems can be configured to log data and provide it when the source and destination are not in regular contact with each other. The publish/subscribe approach is also much better at handling dynamic changes such as adding and removing providers and subscribers.

RTI has also added to their normal licensing scheme with something akin to open source. It essentially limits sharing to a community. This tends to work for a restricted community such as a group of military vendors. The source is open to the community allowing developers to share ideas, applications and the underlying framework but within the restrictions RTI imposes.

This new licensing approach has been well received within some of those communities. It provides access for research and training. It should also allow for more experimentation and cross pollination.

RTI does provide source code for licensees and all products are royalty free. Product pricing is per developer and support for the open source is per hour. The open source version does not include development tools or warranties.

Open source DDS is available from a number of sources including OpenDDS and PrismTech's OpenSplice.

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