ABSTRACT
This chapter describes the special characteristics of Internet of Things (IoT) data and discusses the key components and requirements for developing effective IoT applications. IoT data streams are often collected and published with meta-data, and consequently, the streams have a wide variety of representations. IoT devices have limited power, memory and processing capabilities. IoT resources are distributed and provide data with different structure, qualities and granularities. The key challenge in data aggregation is that the data from multiple resources have different data models and formats. The aggregation can also be from different types of resources, such as traffic monitoring applications where data from various resources are aggregated to identify the traffic update status. Ranking is about prioritization the resources given a set of criteria such as data quality and resource availability. Different ranking mechanisms have been proposed based on multiple criteria such as quality of information, quality of service and user feedback.
