Progress in the development of small low-powered hardware, wireless networking, sensor technology and software services make it possible to build radically new kinds of applications. These sensor network applications are built on top of a large number of low-powered sensor nodes. Writing software for this kind of network can be a challenging task. Commonly used programming abstractions force the programmer to express the global behaviour of a network in terms of local actions taken at individual nodes. We argue that global programming abstractions are needed to express global behaviour of a network. We propose RuleCaster — a system for programming sensor network applications. Instead of writing applications for the networked node, RuleCaster allows to implement an application for the network as a whole. A compiler automatically splits this application specification into several individual tasks and distributes them in the network. Nodes execute the individually assigned tasks.