The area of context aware for structured environments such as homes, buildings, manufacturing, and others similar. However, as transformative initiatives such as the Internet of Things (IoT) take hold, we are dealing with environments that are not so well structured such as the ones mentioned above. One example of such unstructured environments is the vast amount of data gathered by wireless sensor network (WSN) that might have thousands of tiny sensors collecting many sorts of data. In such a case, just about every element of a traditional context aware system must be re-considered. In this talk, we will review the characteristics and features of context aware systems for well-structured environments, the characteristics and features of WSNs, and present a set of requirements for context aware systems suitable for unstructured environments based on WSNs.