Sensor networks are notoriously difficult to program, given that they encompass the complexities of both distributed and embedded systems. To address this problem, we present the design and implementation of a declarative sensor network platform, DSN: a declarative language, compiler and runtime suitable for programming a broad range of sensornet applications. We demonstrate that our approach is a natural fit for sensor networks by specifying several very different classes of traditional sensor network protocols, services and applications entirely declaratively -these include tree and geographic routing, link estimation, data collection, event tracking, version coherency, and localization. To our knowledge, this is the first time these disparate sensornet tasks have been addressed by a single high-level programming environment. Moreover, the declarative approach accommodates the desire for architectural flexibility and simple management of limited resources. Our results suggest that the declarative approach is well-suited to sensor networks, and that it can produce concise and flexible code by focusing on what the code is doing, and not on how it is doing it.

We address the problem of balancing the traffic load in multi-hop wireless networks. We consider a point-to-point communicating network with a uniform distribution of source-sink pairs. When routing along shortest paths, the nodes that are centrally located forward a disproportionate amount of traffic. This translates into increased congestion and energy consumption. However, the maximum load can be decreased if the packets follow curved paths. We show that the optimum such routing scheme can be expressed in terms of geometric optics and computed by linear programming. We then propose a practical solution, which we call Curveball Routing that achieves results not much worse than the optimum.We evaluate our solution at three levels of fidelity: a Java high-level simulator, the ns2 simulator, and the Intel Mirage Sensor Network Testbed. Simulation results using the high-level simulator show that our solution successfully avoids the crowded center of the network, and reduces the maximum load by up to 40%. At the same time, the increase of the expected path length is small, i.e., only 8% on average. Simulation results using the ns2 simulator show that our solution can increase throughput on moderately loaded networks by up to 15%, while testbed results show a reduction in peak message load by up to 25%. Our prototype suggests that our solution is easily deployable.

Over the past decade a variety of network architectures have been proposed to address IP's limitations in terms of flexible forwarding, security, and data distribution. Meanwhile, fueled by the explosive growth of video traffic and HTTP infrastructure (e.g., CDNs, web caches), HTTP has became the de-facto protocol for deploying new services and applications. Given these developments, we argue that these architectures should be evaluated not only with respect to IP, but also with respect to HTTP, and that HTTP could be a fertile ground (more so than IP) for deploying the newly proposed functionalities. In this paper, we take a step in this direction, and find that HTTP already provides many of the desired properties for new Internet architectures. HTTP is a content centric protocol, provides middlebox support in the form of reverse and forward proxies, and leverages DNS to decouple names from addresses. We then investigate HTTP's limitations, and propose an extension, called S-GET that provides support for low-latency applications, such as VoIP and chat.