Abstract The creation of blockchain-based software applications requires today considerable technical knowledge, particularly in software design and programming. This is regarded as a major barrier in adopting this technology in business and making it accessible to a wider audience. As a solution, low-code and no-code approaches have been proposed that require only little or no programming knowledge for creating full-fledged software applications. In this paper we extend a review of academic approaches from the discipline of model-driven engineering as well as industrial low-code and no-code development platforms for blockchains. This includes a content-based, computational analysis of relevant academic papers and the derivation of major topics. In addition, the topics were manually evaluated and refined. Based on these analyses we discuss the spectrum of approaches in this field and derive opportunities for further research.
Despite the recent increase in the popularity of blockchain, the technology suffers from the trilemma trade-off between security decentralisation and scalability prohibiting adoption, and limiting the efficiency and effectiveness of the induced system. Addressing the trilemma trade-off calls for dynamic management and configuration of the blockchain system. In particular, choosing an effective and efficient consensus protocol for balancing the trilemma trade-off when inducing the blockchain-based system is acknowledged to be a challenging problem given the dynamic and complex nature of the blockchain environment. DDDAS approaches are particularly suitable for this challenge, and in previous work, the authors presented a novel DDDAS-based blockchain architecture and demonstrated that it offers a promising approach for dynamically adjusting the parameters of a system and optimising for the trade-off. This paper presents a novel simulation tool that can support and satisfy the DDDAS requirements for a dynamically re-configurable blockchain system. The tool supports the simulation and the dynamic switching of consensus protocols, analysing their trilemma trade-off. The simulator design is modular and allows the implementation and analysis of a wide range of consensus protocols and their implementation scenarios, along with the ability for parallelization. The paper also presents a quantitative evaluation of the tool.
Habib Allah Yajam, Elnaz Ebadi, Mohammad Ali Akhaee
The consensus algorithm is fundamental to the decentralization property of blockchain technology. Developing blockchain networks and consensus algorithms necessitates the analysis of variables on large global-scale networks through experiments. However, conducting experiments on test networks is expensive due to the high cost of necessary infrastructure. In this article, JABS (Just Another Blockchain Simulator), a simulator specifically designed for researching large-scale blockchain consensus algorithms, is introduced. Superior performance in simulating real-world scale blockchain networks compared to other frameworks is demonstrated in this article. JABS is faster, more efficient, and produces accurate results that are comparable to measurements from Bitcoin and Ethereum blockchain networks. JABS' modularity, which allows for the easy substitution of components without changing others, is highlighted. Additionally, JABS aids in the design and evaluation of new consensus algorithms. Improving the CasperFFG consensus algorithm is proposed and its improved performance using JABS is demonstrated.
The metaverse introduces new challenges to the Internet infrastructure and architecture. While virtual reality (VR) applications on mobile devices dominate the current projections, their Quality of Service (QoS) requirements result in increased demand in global low-latency and local high-bandwidth connections. With the introduction of new Internet architectures, the procurement of bandwidth which guarantees such QoS requirements becomes feasible. Time, location and application-dependent QoS requirements and different budgets of user applications create the competition for such bandwidth resources. As such, a market for routing paths and their bandwidth helps to resolve the competition among user applications by determining the market prices and allocations for all demanded links. This work establishes such a market model by leveraging a Fisher market in which prices and fair allocation are determined. To enable the global, cross-jurisdictional nature of connectivity, a distributed solution for global connectivity is presented through a smart contract on the Ethereum blockchain, enabling optimal updates for selfish buyers and feasible prices and bandwidth allocations at every step.
Scalability has grown more important as blockchain technology is adopted. This study introduces RSA-accumulator-based stateless blockchain performance optimization. Verifiable computing technology and distributed design compress node state data and prove smart contract validity, while a new smart contract execution logic and transaction verification scheme solve the problem of transaction verification and execution under stateless conditions, increasing system throughput. The technique reduces consensus node storage and improves throughput compared to Ethereum blockchains, according to experiments. This study examines the scheme's concept, implementation, and blockchain scalability potential.
Data leads to knowledge, being considered crucial for running a successful business. Its production is dramatically increasing, generating challenges into identifying what data is worth extracting and what is not. Complementary to the data value, data marketplaces are becoming increasingly popular serving as the sources for additional data. They offer purchasing and selling capabilities for external data, simplifying data sourcing, while enabling users to navigate today's complex data world. Data marketplaces are continuously developed, serving the requirements of individuals and businesses in industries such as healthcare or telecommunications, with the top ones covering individual online activities and financial information. Above all, bank transactions have altered due to digitalization, with most consumers currently employing Embedded Finance (EmFi) applications. Given that the latter can benefit from accessing data from federated data providers in different sectors and transparent value driven approaches, the existence of EmFi data marketplaces is vital. In this manuscript, the FAME project is introduced aiming to launch a federated EmFi data marketplace. It goes beyond current data marketplaces since it supports the EmFi domain that currently lacks dedicated marketplaces, also offering: (i) a federated data catalogue, (ii) a single-entry point authorization/authentication infrastructure, (iii) a decentralized trading and monetization capability, and (iv) a set of EmFi-related trusted and energy-efficient analytics. All the capabilities of the FAME data marketplace are analysed, depicting the current market status and FAME's advancements. The manuscript concludes into the overall vision of FAME, depicting its applicability and future evaluation processes.
In a sharded blockchain, transactions are processed by a number of parallel committees. Thus, the transaction throughput can be largely boosted. A problem is that some groups of blockchain nodes consume large latency to form committees at the beginning of each epoch. Moreover, the heterogeneous processing capabilities of different committees also result in imbalanced consensus latency. Such imbalanced two-phase latency brings a large cumulative age to the transactions pending in transaction pool. Consequently, the blockchain throughput can be significantly degraded. We believe that a good committee-scheduling strategy can reduce the cumulative age of transactions, and thus benefit the throughput. However, we have not yet found a committee-scheduling mechanism that works for accelerating block formation in the context of blockchain sharding. To this end, this paper studies a fine-balanced tradeoff between the transactions’ throughput and their cumulative age in a large-scale sharded blockchain. We formulate this tradeoff as a utility-maximization problem, which is proved NP-hard. To solve this problem, we propose an online distributed Stochastic-Exploration (SE) algorithm, which guarantees a near-optimal system utility. We then rigorously analyze three theoretical properties of the proposed algorithm, including the theoretical convergence time, the probability of committees’ failure due to Sybil attacks, as well as the performance perturbation brought by committees’ offline events. Finally, we evaluate the proposed algorithm using the dataset of real-world blockchain transactions. The simulation results demonstrate that the proposed SE algorithm outperforms other baselines in terms of system utility, the valuable degree of yielded solutions, latency, and throughput performance.
Abstract: The advancement of blockchain innovation has prompted the making of decentralized applications (DApps), which permit client collaboration without the utilization of mediators. One of the most generally used blockchain stages for making DApps is Ethereum, which conducts business utilizing its own cash, Ether. Using Metamask, React.js, Node.js, and Solidity, we demonstrate the design and implementation of a decentralised system for Ethereum transfer in this paper. Our technology allows users to safely move Ether between accounts without the usage of intermediaries. We use React.js and Node.js to make the web application, a program module called Metamask to communicate with Ethereum, and Solidity to make the brilliant agreements that make exchanges conceivable.
As the significance of blockchain innovation grows and the focus on scalability intensifies, rollup technology has emerged as a promising approach to tackle these scalability concerns. Nonetheless, rollups encounter restrictions when interacting with other rollups, leading to diminished throughput, increased latency, higher fees, and a complex user experience in transactions between rollups. In this paper, we put forth a novel system that employs batch settlement techniques to augment the efficiency of transfers between rollups. Our proposed system comprises a settlement rollup responsible for batch settling transfers among rollups and a smart contract structure that carries out the settlements. Notably, we utilize a zero-knowledge proof algorithm to guarantee the computational integrity of the settlement rollup while ensuring security through Ethereum smart contracts for proof verification and settlement execution. By implementing this approach, the proposed system can effectively and securely execute asset transfers between rollups, ultimately improving their scalability and usability. Consequently, our research provides a fresh perspective on resolving the challenges of throughput, latency, and fees associated with transfer systems.
George Melas, Alexandros Chatzigeorgiou, Apostolos Ampatzoglou
Smart Contracts (SC) are computer programs that run on blockchains and can be executed automatically in a deterministic way, when pre-determined conditions are met. Currently, Ethereum is the biggest blockchain network with more than 200,000 SCs deployed every month[1](#fn-0002). The main mechanism for financially managing and securing such networks is “ Gas Consumption ”. In particular, a gas cost is assigned to each operation that alters the blockchain state, based on the SC size and complexity. Thus, the cost that a SC incurs to its owner and users is related to the internal structure of the SC. By considering that the average cost for deploying a Smart Contract can reach up to thousands of euros, it becomes obvious that internal quality of SCs is of great importance. To this end, in this article we present a comprehensive analysis of the correlation of a set of code metrics (e.g., size, complexity) with the actual gas required to deploy Smart Contracts. The empirical evidence that we provide rely on the analysis of over 90,000 SCs. In addition to the produced empirical knowledge, in most of the cases validating the theoretical expectation, we have implemented a web-based application (Smart Contracts Quality Analysis Platform—SCQAP) that visualizes the findings, enabling the on-demand creation of correlation diagrams, and offers access to a public repository of our data (metrics and deployment gas consumption) via a REST API. To the best of our knowledge this is the biggest empirical study on SCs, which: (a) sets up the scene for further large-scale studies on Smart Contracts (through tooling and public dataset); and (b) provides guidance to software practitioners on parameters that can inflate deployment costs.
Cloud storage system provides on-demand and pay-per-use storage models with low computing costs. However, this storage system suffers from various security risks. Blockchain technology is an advanced technique that stores data in a distributed manner, and once the data are stored, it cannot be altered. Therefore, a blockchain-based distributed architecture has been proposed in this paper for the cloud storage system. The proposed scheme utilizes the functionality of the smart contract to provide security features to the stored cloud data. The proposed scheme encodes the data before uploading it to the cloud server to achieve confidentiality. Furthermore, the proposed system includes an enhanced optimization technique and a challenge-response-based integrity checking mechanism, which provides a more secure cloud environment. The proposed technique also minimizes the system bandwidth cost using an enhanced fruit fly optimization algorithm that optimizes the node failure repair process. The experimental results and performance evaluation show that the proposed scheme is secured and reliable for the cloud computing environment.
In recent years, consortium blockchain has played a significant role in fields such as logistics traceability and data transactions. However, due to the large differences in the underlying implementations of consortium blockchains, it is difficult to establish effective data sharing between different chains. Cross-chain technology is an important means to break the data isolation status of consortium blockchains, but the existing cross-chain technologies cannot meet the requirements of cross-chain supervision of consortium blockchain. There is no clear authority to divide cross-chain requests and inter-chain interoperability, and the contract calls between chains may lead to malicious tampering with ledger data during the cross-chain process, making them unsuitable for cross-chain supervision scenarios. In view of the above problems, this paper propose a cross-chain supervision mechanism of distributed notaries for consortium blockchain. The mechanism selects high-credit nodes from each consortium blockchain to serve as notaries and forms a notary chain as a medium for cross-chain sharing. By grading the identities of access chains, the security of cross-chain operations is ensured, the scalability of cross-chain is realized by modular design, and the communication message protocol designed for cross-chain supervision ensures the security of the supervision process. Finally, we compare and analyze our proposed solution with existing mechanisms and verify the practicability of the proposed scheme through simulation experiments.
Blockchain proposes many innovative technologies to establish credible mechanisms in an open environment and therefore, it becomes a promising solution to the problem of credibility in educational development. To better understand the role of the blockchain, we aim to provide an extensive survey focusing on its key technology, application potential, and performance evaluation. First, from the perspective of blockchain characteristics, we summarize its application architecture in educational credibility. Next, we extensively discuss application potential of the blockchain, such as data storage, data sharing, achievement certification, and activity evaluation. Moreover, we investigate the performance evaluation, including basic performance metrics and specialized metrics for credibility. Finally, we analyze the challenges and research trends of blockchain in educational credibility and provide useful insights for future research.
Ronan D. Mendonça, Ericksulino Moura, Glauber Dias Gonçalves, Alex Borges Vieira · 5 authors
Blockchain é uma tecnologia que amplia a segurança nas relações entre organizações via o registro auditável e descentralizado de transações. Notadamente, há uma crescente atenção por aplicações que utilizam essa tecnologia. Entretanto, a eficiência e custo de tais aplicações pode ser influenciada pela rede blockchain utilizada. De fato, a escolha da rede impacta nas qualidades não funcionais das aplicações, em especial desempenho (e.g., em relação a taxa de transações efetivadas) e custo. Este artigo investiga o impacto no desempenho e custo da infraestrutura de rede blockchain para lidar com uma determinada carga de trabalho. Primeiramente, este artigo propõe um modelo de arquitetura de rede comum entre a rede pública Ethereum e permissionada Hyperledger Fabric com base em recursos por nó par da rede blockchain. A seguir, avalia-se o custo por transação para aplicações nessa arquitetura considerando latências e custos mínimos para os pares da rede, em função da carga de trabalho. Os experimentos realizados nas plataformas mais populares para redes blockchain, Ethereum e Hyperledger Fabric, mostram os limites de escalabilidade dessas plataformas e os seus compromissos entre custo e desempenho no projeto de aplicações baseadas em blockchain.
Qian Zhang, Shangping Wang, Duo Zhang, Jifang Wang · 5 authors
The low throughput of traditional blockchain can hardly support the demand of high-frequency and high-concurrent application scenarios, which severely restricts the practical application of blockchain and becomes a bottleneck for blockchain development. Sharding is a potential solution to this issue. Existing sharding schemes mostly use complicated PBFT or its variants consensus protocols, with diminishing consensus performance as the number of nodes grows, and global consistency of transaction data is a challenge due to parallel block generation. Aiming at the above problems, we propose an efficient and scalable sharding blockchain system named FortunChain that comprises a verification chain and multiple sharding chains. In the FortunChain, a novel Tyche consensus protocol is designed to select the set of sharding verification nodes and accounting nodes probabilistically leveraging the newly constructed elliptic curve-based verifiable random function (EC-VRF), which ensures the efficiency, unpredictability and security of node selection. Multi-period, fast and dynamic sharding accounting is implemented in the sharding chain to improve the performance of transaction processing. After that, the verification chain is responsible for the secondary verification by applying the batch verification algorithm to the blocks submitted by the shards and then generating the verification block. Each shard stores the sharding state by synchronizing the verification chain to realize the state sharding and ensure the global consistency of the transaction data. Simulation results show that the throughput of FortunChain can reach approximately 6540tx/s and the estimated latency is 8.59s, which demonstrates its efficiency and feasibility.
The problem of resource-saving scheduling in a fog environment is considered in this paper. The objective function of the problem in question presupposes the fog nodes’ reliability function maximizing. Therefore, to create a schedule, the following is required: the history of the fog devices’ state changes and the search space, which consists of preselected nodes of the cloud-fog broker neighbourhood. The obvious approach to providing the scheduler with this information is to poll the fog nodes, yet this can consume the unacceptable time because of the QoS requirements. In this paper, the system architecture and general methods for efficient resource-saving scheduling is presented. The system is based on distributed ledger element usage, which provides the nodes with the proper awareness about the surroundings. The usage of the distributed ledger allows not only for the creation of the resource-saving schedule but also the reduction of the scheduling problem-solving time, which frees addition time that can be used for the solving of user tasks. The latter also affects the overall resource-saving via reliability. The novelty of this paper consists in the development of the hybrid ledger-based system, which integrates and arranges the elements of various ledger types to solve the newly formulated problem.
The current education system emphasizes memorization and high test scores, leading to disinterest and a lack of motivation among students. A more comprehensive educational approach that integrates hands-on learning, real-world applications and the development of critical thinking skills is proposed. Decentralization and transparency are two critical issues that impact the education system, and addressing them through initiatives such as increased openness in decision-making processes and accountability can improve the system. This research work proposes using Blockchain technology in education to provide recognition for students’ skills, secure and transparent verification of their academic history, and a more engaging and rewarding learning experience. A proof of concept is proposed, an incentive-based skill development platform that uses Ethereum smart contracts and cryptographic tokens to reward students’ efforts.
Blockchain has received a lot of attention due to its immutability. However, the immutability characteristic prohibits editing the blocks which need to be modified. Although the existing redactable blockchain enables to manipulate blocks in a controlled way, it may suffer from the security threats if the number of honest committee members (CMs) is insufficient. Thus, to attract honest CMs for validating and voting the editing blocks in permissionless blockchain, this paper presents a contract-based incentive mechanism between contract issuer and every CM. Firstly, it models the interaction between the contract issuer and each CM in the verifying and voting process. Secondly, it builds an incentive mechanism according to the contract issuer’s cost and the committee size. Finally, it selects a sufficiently large number of CMs with an optimization method. The analysis shows that the present mechanism is secure against Sybil attack, and the simulations demonstrate that the proposed mechanism is effective.
Blockchain oracles are an intermediary designed to connect external non-deterministic information and real-world data to the blockchain digital infrastructure. The variety of proposed solutions and purposes are of great variety and suggest that it is necessary to take into account different features of the process and specifically define the required functionalities. The purpose of this paper is to present the integration of oracles into an EOSIO blockchain-based platform for smart crop production data exchange by smart contracts. The functions of two oracles are presented. Their integration is described at the design level and at the implementation of the smart contracts. The design level is illustrated by workflow diagrams of internal processes between oracle applications and the blockchain smart contract and by external processes in the oracles’ smart contracts. The implementation level is illustrated by oracle application configuration files and elements of C++ smart contracts, such as constant and variable declarations, multi-index tables, internal contract functions, and actions called by other contracts and external programs. As results of the oracles’ operation, a report on the detected emergency failures and an estimate of the cost of ram resource are presented.