Programming Ad-hoc Networks of mobile and resource-constrained devices

Ad-hoc networks of mobile devices such as smart phones and PDAs represent a new and exciting distributed system architecture. Building distributed applications on such an architecture poses new design challenges in programming models, languages, compilers, and runtime systems. This paper discusses SpatialViews, a high-level language designed for programming mobile devices connected through a wireless ad-hoc network. SpatialViews allows specification of virtual networks with nodes providing desired services and residing in interesting spaces. These nodes are discovered dynamically with user-specified time constraints and quality of result (QoR). The programming model supports "best-effort" semantics, i.e., different executions of the same program may result in "correct" answers of different quality. It is the responsibility of the compiler and runtime system to produce a high-quality answer for the particular network and resource conditions encountered during program execution. Four applications, which exercise different features of the SpatialViews language, are presented to demonstrate the expressiveness of the language and the efficiency of the compiler generated code. The applications are an application that collects and aggregates sensor data in network, an application that performs dynamic service installation, a mobile camera application that supports computation offloading for image understanding, and an augmented-reality (AR) Pacman game. The efficiency of the compiler generated code is verified through simulation and physical measurements. The reported results show that SpatialViews is an expressive and effective language for ad-hoc networks. In addition, compiler optimizations can significantly improve response times and energy consumption.