By John McHale
SUNNYVALE, Calif. — Experts at Real-Time Innovations (RTI) are providing a real-time software tool for the U.S. Navy San Antonio-class amphibious transport dock ship (LPD-17) to help lower development costs.
Engineers at Raytheon`s Naval and Maritime Systems group in San Diego chose RTI`s Network Data Delivery Service (NDDS) Version 2.2 to ease integration on the San Antonio`s shipwide area network (SWAN), which they designed. The SWAN interconnects navigation, communications, machinery control, damage control, and other non-combat systems.
"We have used various types of communications techniques in the past with mixed results," a Raytheon official says. "NDDS is by far the best. We plan to add additional nodes to our system." SWAN moves imagery, voice, and video data.
NDDS is a network middleware that enables real-time distribution of critical data over a standard Ethernet connection, says Brett Murphy, director of marketing at RTI. Instead of writing 100,000 lines of socket code, programmers can interface to one set of Application Program Interfaces (APIs) rather than several application drivers, Murphy adds.
The middleware architecture for SWAN is based on RTI`s real-time, publish-subscribe model commercialized in the NDDS toolkit. End-user applications communicate on the SWAN through standard interface components called stackware and APIs, RTI officials say.
APIs minimize the need for several unique software interfaces such as drivers and message translators. The APIs interface with middleware components such as gateways, and brokers that mediate messaging among different applications, databases, hardware, and operating systems, including platforms as different in purpose and use as VxWorks and Windows NT, RTI officials say.
"The publish-subscribe architecture eliminates our customers` network programming headaches," says Stan Schneider, RTI President. "And the NDDS`s real-time publish-subscribe model adds the determinism, fast distribution, small size, and robustness missing from the basic architecture."
This latest release of NDDS adds dynamic node detection and multiple network interface card (NIC) support to help reduce costs and reduce network downtime, RTI officials say. Dynamic node detection lets the developer add and remove publishers and subscribers, without shutting down the network, modifying the application, or re-initializing NDDS configuration parameters.
Developers want several NICs for redundant networks and 24 hours, seven days-a-week availability. NDDS provides transparent multiple NIC support, the application needs no modification to work over redundant networks.
NDDS 2.2 uses 30 percent less memory and supports larger packets than the previous version. The RTI tool adds C++ support to the existing C API as well.
Publish-subscribe is gaining in popularity because it simplifies network programming, RTI officials claim. Data publishers and subscribers are decoupled from each other; publishers simply send data and subscribers receive it.
The middleware takes care of all the complex addressing, message-passing, error-handling, and other networking chores. For applications with one- and many-to-many data distribution requirements, publish-subscribe substantially reduces the lines of code and learning curve, especially over client server and distributed object models such as CORBA and DCOM.
Publish-subscribe alone is not suitable for real-time applications, however, RTI officials say. They have added formal extensions that allow developers to implement timing models, balance data delivery determinism versus reliability, manage quality of service, and protect real-time thread performance. NDDS uses standard IP protocols to provide fast, deterministic data delivery over Ethernet, eliminating the need for expensive, proprietary networks for device-to-controller communications, RTI officials claim.
NDDS is also used to combine the different pieces in a flight simulation environment Shipboard Communications Research.
For more information on NDDS contact Real-Time Innovations by phone at 408-720-8312, by fax at 408-734-5009, by mail at Real-Time Innovations, 155A Moffett Park Drive, Suite 111, Sunnyvale, Calif., or on the World Wide Web http://www.rti.com.
