As wireless sensor networks become increasingly integrated with the Internet, the Internet of Things (IOT) is beginning to emerge. The IOT is a massive cyber-physical system that presents many software engineering challenges. One fundamental challenge is the need for multi-dimensional QoS that can satisfy the individual constraints of the many participants in the system. In this paper, we investigate the challenges of providing such a mechanism via a simple abstraction consisting of a general QoS function provided by each application. This function distills the multi-dimensional QoS specifications from each stakeholder into a single value that is used to determine the best configuration of interactions. We prototype our approach in a real wireless sensor network using a pervasive healthcare fall-detection application and highlight the many challenges it unveils.