Abstract
Abstract Wireless sensor networks (WSN) are usually used to monitor the environment. As the environment changes, we will need to change the task running on WSNs. Therefore, a concise way to reprogram each sensor node is required. Since WSNs typically contain a large amount of sensor nodes, it is difficult to retrieve them back and download new programs one by one. What is required is a power and resource efficient way of reprogramming the senor nodes in place. This is further complicated by the popularity of heterogeneous WSNs – different types of sensors require different code. To solve the problems of code portability and energy-efficient reprogramming, this thesis introduces “Barista”, a light-weight Java virtual machine developed for wireless sensors. The goal is to create a low power consumption, low memory usage and low OS resources Java virtual machine. With Barista, users can use their familiar Java language to program their WSN applications. The resultant code will be highly portable and small enough for efficient dissemination to the sensors. We have implemented Barista on TinyOS. The result shows that Barista can run on a resource limited device (32KB ROM and 1KB RAM) and the lifetime of the node is shortened by 6% only.