Complex queries over decentralised systems for geodata retrieval

Abstract

Decentralised systems have been proved to be quite effective to allow for trusted and accountable data sharing, without the need to resort to a centralised party that collects all the information. While complete decentralisation provides important advantages in terms of data sovereignty, absence of bottlenecks and reliability, it also adds some issues concerned with efficient data lookup and the possibility to implement complex queries without reintroducing centralised components. In this paper, we describe a system that copes with these issues, thanks to a multi-layer lookup scheme based on Distributed Hash Tables that allows for multiple keyword-based searches. The service of peer nodes participating in this discovery service is controlled and rewarded for their contribution. Moreover, the governance of this process is completely automated through the use of smart contracts, thus building a Decentralised Autonomous Organization (DAO). Finally, we present a use case where road hazards are collected in order to test the goodness of our system for geodata retrieval. Then, we show results from a performance evaluation that confirm the viability of the proposal. | INTRODUCTIONThe digitalisation process, which has been ongoing over the last decades, has seen data management and data delivery become crucial issues. The transformation brought about by digital technologies has data at its core and it had a significant impact on economies and societies around the world. The ability to easily get hold of data has the potential to create several new services based on data and new markets where more and more users are consumers and providers at the same time. However, obtaining large amounts of data that is not from a dubious (or false) origin is often a challenge. In order to cope with the increasingly higher number of content that is demanded through the Web, multiple solutions for efficient use of the Internet have been designed. In particular, thanks to the decentralisation of content storage and delivery, it is possible to avoid the single point of failure, while reducing the workload at data centres and allowing a distribution of data that remains 'closer' to the original data producer. Decentralisation also fosters the creation of open systems, where participants can freely join the system and then contribute to its functioning.Recently, Distributed Ledger Technologies (DLTs) and a realm of decentralised systems, for example, Decentralised File Storages (DFS), have emerged as Peer-to-Peer (P2P) technologies capable of offering interesting features related to data validation and trustfulness [2,3]. DLTs have gained popularity with the advent of cryptocurrencies, which allow users to trade crypto-assets without any central entity being involved, ensuring transparency and data integrity. By creating a common, decentralised and trustless infrastructure, it will be possible for data consumers and providers to interact and collaborate in P2P interactions [4,5]. Benefits often cited of DLTs, indeed, include the enabling of ...

Keyword-Based Multimedia Data Lookup in Decentralized Systems

“…A more inherent work to the topics discussed in this paper is found in [21], in which the authors implemented a Road Hazard Detection search system for selfdriving vehicles. The architecture is based on IOTA DLT to save the locations of possible road hazards and search for those locations using a hypercube-shaped DHT in which the ID of the transitions containing the information are stored.…”

Proof of Location through a Blockchain Agnostic Smart Contract Language

“…In order to ease the discovery of data, we included in the system a Hypercube DHT [2]. The Hypercube is a Distributed Hash Table (DHT) that, similarly to other content addressable networks, organizes peers (and contents) in a n-dimensional Cartesian coordinate system.…”

“…Nowadays, many users' activities are supported by a different number of mobile applications, leveraging their position to offer specific location-based services. For example, trustworthy crowd-sourcing of urban or environmental obstacles for accessibility purposes [1], [2], customer-loyalty reward systems that offer discounts to users who frequently visit the shop, privacy-preserving contact tracing [3].…”

“…the certificate generated by the PoL service) in a private, decentralized, and distributed way, using nearby users as witnesses. In particular, the proposed system exploits (i) IPFS [8] to store data; (ii) a Distributed Hash Table (DHT) organized as a hypercube [2] to manage all the discovery activities to locate, witness, and verify that the LP is correct; (iii) smart contracts to automatically handle all the interactions among the involved entities in the LP generation and verification.…”

DLT-based Data Mules for Smart Territories

“…In essence, participation in collaboration-based services can be traced and rewarded thanks to Smart Contracts. In particular, a Smart Contract can be devoted to the distribution of digital tokens to those parties that share its resources or cooperate in a communication protocol [12], [13].…”