Abstract
We address the problem of providing users, namely non specialists, with out-of-the-box, programmable, Wireless Sensor-Actuator Networks (WSN). The idea is that users get a package containing a gateway and an undetermined number of nodes, pre-configured to work as a self-organized wireless mesh. Each node comes with two pre-installed components: a small operating system and a virtual machine. The user can then use a simple, domain-specific, programming language to implement periodic tasks that are compiled into byte-code, and can be sent to the nodes for execution. At the nodes, the operating system manages a task table and schedules non-preemptive tasks for execution using the virtual machine. No subtle hardware or software configuration is required from the user as these details are abstracted away by the virtual machine. We developed a full specification for a data-layer that follows the aforementioned guidelines and implemented a complete prototype, integrated in our own Publish/Subscribe middleware called SONAR. In this paper we report the first results of using the prototype as compared to using the low level programming tools provided with the hardware. We measure a small increase in both resource consumption and processing overhead suggesting that this data-layer can be used effectively in WSN, even in cases where nodes have very limited hardware resources.