Resource Optimization of Stream Processing in Layered Internet of Things

IoT (Internet of Things) applications often involve stream processing using multiple complex layers of processing nodes, where in each layer, data is received by the nodes, processed, and then transmitted to the nodes in subsequent layers. Such systems present a tradeoff between reliability and resource usage, including CPU power, energy, network band-width, memory, etc. Reducing the reliability at which a node processes inbound data in a layer can have repercussions on nodes in subsequent layers in the network that receive less reliable data, and in turn impact the reliability of the application as a whole. In this paper, we present a generalized model of streaming IoT applications as a layered network of producers and consumers. Our model captures trade-offs between reliability and resource usage of the system. We present an efficient algorithm using SMT constraint solvers to determine the optimal selection of processing quality for each node in the network, such that target system reliability is achieved while respecting the given resource bounds, and resource usage is minimized. In addition, we present a lightweight machine learning based solution to drastically improve our model in terms of run time. We have fully implemented our technique and report experimental results on a layered IoT network.