NesC
Encyclopedia
nesC pronounced "NES-see", is a component-based, event-driven
programming language
used to build applications for the TinyOS
platform. TinyOS is an operating environment
designed to run on embedded devices used in distributed wireless sensor network
s. nesC is built as an extension to the C programming language
with components "wired" together to run applications on TinyOS.
The basic concepts behind nesC are:
Event-driven programming
In computer programming, event-driven programming or event-based programming is a programming paradigm in which the flow of the program is determined by events—i.e., sensor outputs or user actions or messages from other programs or threads.Event-driven programming can also be defined as an...
programming language
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
used to build applications for the TinyOS
TinyOS
TinyOS is a free and open source component-based operating system and platform targeting wireless sensor networks . TinyOS is an embedded operating system written in the nesC programming language as a set of cooperating tasks and processes. It is intended to be incorporated into smartdust...
platform. TinyOS is an operating environment
Operating environment
The operating environment in engineering describes the circumstances surrounding and potentially affecting something that is operating. For example electronic or mechanical equipment may be affected by high temperatures, vibration, dust, and other parameters which comprise the operating...
designed to run on embedded devices used in distributed wireless sensor network
Wireless sensor network
A wireless sensor network consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants and to cooperatively pass their data through the network to a main location. The more modern...
s. nesC is built as an extension to the C programming language
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
with components "wired" together to run applications on TinyOS.
The basic concepts behind nesC are:
- Separation of construction and composition: programs are built out of components, which are assembled ("wired") to form whole programs. Components have internal concurrency in the form of tasks. Threads of control may pass into a component through its interfaces. These threads are rooted either in a task or a hardware interrupt.
- Specification of component behaviour in terms of set of interfaces. Interfaces may be provided or used by components. The provided interfaces are intended to represent the functionality that the component provides to its user, the used interfaces represent the functionality the component needs to perform its job.
- Interfaces are bidirectional: they specify a set of functions to be implemented by the interface's provider (commands) and a set to be implemented by the interface's user (events). This allows a single interface to represent a complex interaction between components (e.g., registration of interest in some event, followed by a callback when that event happens). This is critical because all lengthy commands in TinyOS (e.g. send packet) are non-blocking; their completion is signaled through an event (send done). By specifying interfaces, a component cannot call the send command unless it provides an implementation of the sendDone event. Typically commands call downwards, i.e., from application components to those closer to the hardware, while events call upwards. Certain primitive events are bound to hardware interrupts.
- Components are statically linked to each other via their interfaces. This increases runtime efficiency, encourages robust design, and allows for better static analysis of programs.
- nesC is designed under the expectation that code will be generated by whole-program compilers. This should also allow for better code generation and analysis.