Disponibilidade de dados para sistemas de informação em cidades inteligentes durante desconexões de rede: uma abordagem utilizando blockchain, oráculo e computação em névoa

Abstract

This work presents an architecture that allows Information Systems functioning even in moments of network disconnection, using the Healthcare Units (HCU) as use case. The architecture uses a blockchain as a distributed database and one of its nodes is physically located inside an HCU, connected to its Local Area Network (LAN). This node is used in disconnection moments between the LAN and the Internet to keep answering the query requests made by authenticated users on the LAN, working as a fog layer. It is also possible to generate new data and, with the help of a reliable oracle, write it to a local database. In disconnection moments the architecture explores the blockchain-isolated node behavior, as well as the functionality of an oracle to record the new generated data. In this way it is possible ensure that the data consulted is the same as that on the blockchain prior to disconnection. It is also possible to aggregate enough information about the new generated data to ensure its integrity. In addition, this information ensures the traceability and auditing of this data. An architecture prototype was implemented and used for execution tests. The test results show that the proposed architecture can maintain the information system working properly during some network outage. In this way, the architecture increases the resilience of the system, being its application suitable for a smart city scenario, where data availability is desired.