Advancing Sensor Web InteroperabilityApril 1, 2005 By: Bryan L. Gorman, Mallikarjun Shankar, Cyrus M. Smith Sensors
SensorNet is a vendor-neutral interoperability framework for Web-based discovery, access, control, integration, analysis, and visualization of online sensors, sensor-derived data repositories, and sensor-related processing capabilities. In other words, SensorNet attempts to create a wide-area system to collect and analyze data from sensors all over the country to monitor and detect threats, and then alert agencies, emergency responders, and others as necessary. It is being designed and developed by the Computational Sciences and Engineering Division at the Oak Ridge National Laboratory (ORNL), in collaboration with the National Oceanic and Atmospheric Administration (NOAA), the Open Geospatial Consortium (OGC), the National Institute for Standards and Technology (NIST), the Department of Defense, and numerous universities and private-sector partners. The purpose of SensorNet is to provide building blocks for a comprehensive nationwide system for real-time detection, identification, and assessment of chemical, biological, radiological, nuclear, and explosive hazards.
The SensorNet team is developing prototypes to network a variety of sensors for strategic test beds at military installations, traffic control points, and truck weighing stations. The sensor networks are connected by secure and redundant communication channels to local, regional, and national operations centers. These network test beds will provide a basis for interfaces to 911 centers, mass-notification networks, automated predictive plume modeling applications, and evacuation models (see Figure 1).
Figure 1. SensorNet lays the groundwork for rapid deployment of a nationwide real-time detection system.
From a national security perspective, SensorNet addresses the problem of isolated, custom-designed, single-application sensor networks, incompatible sensor standards, lack of real-time availability of data, and lack of common and consistent schemas for sensor description, control, and data. Homeland security and force protection are areas of particular interest, but the same issues apply in many other public and private sector domains.
Transducer and Application Interfaces
In developing an open standards framework for interoperable sensor networks, there needs to be a universal way to connect two basic interface types—transducer interfaces and application interfaces. Operational specifications for sensor interfaces generally mirror hardware constraints, while specifications for service interfaces are closer to application requirements. The sensor interfaces and application services need to work together and thus may need to be bridged at any of the various locations in the deployment hierarchy.
For the transducer interfaces, SensorNet adopts the methodology advocated by the IEEE 1451 working groups that are developing plug-and-play standards for smart transducers. A transducer is "smart" when it includes sufficient descriptive information to allow control software to automatically determine the transducer's operating parameters, decode its electronic data sheet, and issue commands to read and actuate the transducer. The IEEE 1451 standard data sheet encoding scheme is critical. In the past, when each transducer had a separate and nonstandard data sheet, it was necessary to write custom software to talk to each transducer.
For application interfaces, SensorNet builds on Web services. Although control granularity and latency constraints preclude the use of Web services for some end-to-end control tasks, SensorNet uses them for most interactions including user-directed control. Web-resident service directories and data dictionaries provide consistent terminology so application services can work together.
The Geospatial Component
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