A Time-Varying JSON Data Model and Its Query Language for the Management of Evolving Green Things in IoGT-Based Systems

Internet of Green Things (IoGT) is a technology that allows exchanging information between people and healthy farm things. It provides information like soil moisture, temperature, humidity, and nutrient level via the use of appropriate sensors. IoGT sensor data represent entities which are evolving over time, and several (smart) farming applications require bookkeeping of the entire history of such data. Furthermore, IoGT data could be considered as big data since they satisfy the three Vs of big data (Volume, Velocity, and Variety), and the standard JSON format is considered one of the best data formats to efficiently manage (i.e., model, store, and exchange) big data. Nevertheless, to the best of our knowledge, there is no standard time-varying data model for IoGT data management, on the one hand, and the JSON format does not provide any explicit and native support for handling temporal data, on the other hand. Hence, in order to manage the evolution over time of big data and time-varying IoGT data, both designers and developers of smart farming applications should proceed in an ad hoc manner. In order to fill this gap, we propose in this chapter TIoGT (temporal JSON IoGT) data model, a temporal extension of the JSON data model, for an efficient management of temporal and evolution aspects of data and green things in IoGT-based systems. Moreover, we define a user-friendly query language for such a model, named QL4TIoGT (Query Language for TIoGT), to be used for querying time-varying green things and exploiting TIoGT data.