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The article discusses the hardware and software that go into creating wireless sensor networks (WSNs). Topics include the hardware characteristics of smart wireless sensor devices, wireless communications stacks, sensing stacks, middleware services, the operating system, and software application. WSNs have current and potential applications in energy, medicine, military applications, and agriculture. WSNs can be attached to the Internet, and future developments may see WSN data available via Internet search engines.

Real-time systems are those systems in which the correctness of the system depends not only on logical results of computation but also on the time at which those results are produced. They span a broad spectrum of complexity from very simple microcontrollers in embedded systems to highly sophisticated, complex and distributed systems. Most embedded systems consist of a small microcontroller and limited software situated within some product such as a microwave oven or automobile. However, with the increasing sophistication of such systems, powerful microcontrollers and digital signal processing chips are commonly used, as are off-the-shelf real-time operating systems and design and debugging tools. Distributed multimedia have produced a new set of soft real-time requirements. Real-time principles lie at the heart of distributed multimedia, but without the concomitant high reliability requirements found in safety-critical, hard real-time systems. The confluence of real-time databases, multimedia and real-time control has great potential for moving application areas such as manufacturing and process control into the next generation.

Presents information on the development of a real-time operating system kernel, called the Spring Kernel to address the need for satisfying specific deadline and periodicity constraints. Details on current real-time operating systems as of 1991; Considerations for next-generation real-time systems; Criteria for classifying tasks in real-time systems.