Military Embedded Systems

Preserving legacy systems, by choice or necessity


February 11, 2010

J.M. Schlesselman

Real Time Innovations (RTI)

Sometimes the best approach to preserving and extending aging military systems is the addition of modern protocol adapters. Consequently, new hardware and software come together to bring legacy equipment data into the network-centric world.

The U.S. Navy has an acute need to support legacy network systems while constantly adding new capabilities. This situation can span decades when today’s new capability becomes tomorrow’s legacy.

Some U.S. Navy programs are beginning to adopt computing plant technology insertion schedules that plan hardware upgrades every four years and software every two years. This approach ensures reasonably current technology, avoiding the life-cycle support problems of sourcing obsolete computer hardware for 10- to 20-year-old equipment.

But a problem remains: Not every ship system gets upgraded with the computing plant. How is today’s technology integrated into older systems first developed in the ’80s and ’90s – without incurring unaffordable integration costs?

There are many possible solutions. One option is to rewrite and replace legacy software in the computing plant. Historically, this has proven very time consuming and costly. Other options include the development of bridging, routing, translating, or virtualization techniques. However, reprogrammable protocol adapters and Data Distribution Service (DDS) comprise the primary solutions.

Problem: Legacy sensors and weapons integration

The need to integrate existing systems with new capabilities is a common problem. For example, the U.S. Navy Cooperative Engagement Capability (CEC) program presents an integration challenge. CEC enables battle group ships and aircraft to share sensor (for instance, radar) track data, providing the entire battle group with a coherent, integrated air track picture.

CEC forms network-based tracks using existing sensors. However, the legacy system also creates a local track picture using the same sensors. A number of technical issues must be addressed to integrate both track managers: Sensor data provided to the CEC and the legacy system is neither time synchronized nor normalized. Additionally, the legacy system is not capable of immediately servicing requests from other applications that want to make use of sensor data. Sending raw sensor data to both systems results in track inconsistencies requiring resolution via additional algorithms.

Solution 1: Reprogrammable protocol adapters

Reprogrammable protocol adapters that translate legacy interface protocols (for example, NTDS-A/B/C/D/E) into current Internet Protocol-based DDS and Web Services (WS) protocols are easing the challenge of integrating old and new technologies. One such converter is Advanced Fusion Technologies’ Open System Interface Adapter (OSIA).

OSIA abstracts the details of managing the legacy interface protocol, such as I/O chain management, from software applications running in the distributed computer plant. It also removes the computational burden of data formatting and input/output conversions. Instead of these cumbersome tasks, OSIA transfers data to software applications using standard Interface Design Language (IDL) formats. It enables applications to simply discover and subscribe to topic data via the DDS protocol using application-specific topic Quality of Service (QoS) parameters. Such protocol adapters also provide remote access to legacy data for browser-based applications via standard WS protocols. The resultant protocol adaptations lead to greatly simplified application integration.

Solution 2: Data Distribution Service

The other key old-and-new integration enabler is DDS software in the legacy computer distributed computing platform. DDS is the DoD-mandated standard for real-time publish/subscribe communications. Its chief benefit for legacy systems is that it facilitates an evolution from application-specific interfaces to data-centric programming. Data-centricity decouples information consumers (called “subscribers”) from information producers (called “publishers”). This loose coupling between publishers and subscribers, complemented with fast and efficient bridging hardware, allows decades-old equipment to remain valuable in today’s modern, IP-based systems.

The final result: Systems comprising old and new

The end result is a system that meets the competing needs of preserving the U.S. Navy’s investment in legacy computing hardware while enabling the Navy’s transition to an Open Architecture Computing Environment (OACE). Using OACE standard interfaces reduces costs by fostering competition, reuse, and interoperability. Bring reprogrammable protocol converter technologies into the picture, in addition to DDS, and costs decrease by allowing new and legacy systems to interoperate, eliminating the need to upgrade all systems in lockstep. This also reduces the cost of future technology insertions by having legacy equipment present the same interface as new equipment. This in turn allows procurement and R&D funding to be directed at the areas in which they will have the greatest impact.

J. M. Schlesselman is director of aerospace and defense technologies at RTI. He has worked as a software developer, system integrator, and military officer. Joseph holds a Master of Science in Management Science and Engineering from Stanford University. He can be contacted at [email protected].


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