一种动态无线传感网络操作系统－SOS

A Dynamic Wireless Sensor Network Operating System-SOS

无线传感器网络节点，在一般用途的系统和嵌入式系统里都有自己的特点。有时必须在能源很少并且环境比较恶劣的情况下工作，同时还提供共同服务，使它很容易编写应用程序。在当前流行的无线传感网络操作系统TinyOs下，虽然各个组件可以互相提供共同服务，但是每个传感器节点必须单独的运行一个静态的系统镜像，所以很难满足多维应用的系统或者频繁的应用更新。SOS，一种从设计上更考虑动态性的更适合微型节点的操作系统应运而生。它由一个公共的内核和模块组成，它有自己的消息机制．动态内存机制，可以动态加载和动态卸载模块，以及其他的一些服务。然而模块之间是通过一个相互的预定协作机制相互联系的．没有内存的保护。但是尽管如此，SOS通过一系列自己的手段有效的克服了这些缺点，比如看门狗定时器，垃圾回收系统等等。相互独立的模块之间，可以通过最小的系统终端来添加或者删除。通过对比，虽然SOS是动态设计并且使用了更高的内核接口．但是跟TinyOs相比，总的使用开销却是基本一样的。SOS是基于模块化的，容易编程。TinyOS是基于组件化，效率高。而MantisOS可以支持多线程，但是代码占用空间大。由此可以看到，SOS是一个具有自己的特点和优势的无线传感网络操作系统。

Sensor network nodes exhibit characteristics of both embedded systems and general-purpose systems. They also provide common services that make it easy to write applications. In TinyOS, the current state of the art in sensor node operating systems, reusable components implement common services, but each node runs a single statically-linked system image, making it hard to run multiple applications or incrementally update applications.SOS, a new operating system for mote-class sensor nodes that takes a more dynamic point on the design spectrum. SOS consists of dynamically-loaded modules and a common kernel, which implements messaging, dynamic memory, and module loading and unloading, among other services. Modules are not processes： they are scheduled cooperatively and there, is no memory protection. Nevertheless, the system protects against common module bugs using techniques such as typed entry points, watchdog timers, and primitive resource garbage collection. Individual modules can be added and removed with minimal system interruption.We describe SOS＇s design and implementation, discuss tradeoffs, and compare it with TinyOS Our evaluation shows that despite the dynamic nature of SOS and its higher-level kernel interface,its long term total usage nearly identical to that of systems such as TinyOS.SOS is based on roodtries and is easy to program,TinyOs is based on framework and has more effective,MantisOS supports multi-threaded, but needs large code space. It can be seen, SOS is one with its own characteristics and advantages of wireless sensor network operating system.