Fabien Geyer, Holger Kinkelin, Hendrik Leppelsack, Stefan Liebald · 7 authors
Blockchain-based Distributed Ledger Technology (DLT) is a novel paradigm to create tamper-resistant execution environments and data storage for distributed applications on top of a peer-to-peer network. This technology has shown to be of interest in many use-cases, especially in industrial processes where multiple shareholders would like to process and share data in a secure and accountable way. In this work, we evaluate the performance of a DLT-based system via modeling and a quantitative performance evaluation, focusing on the impact of the underlying communication network. Our numerical evaluation is based on the Hyperledger Fabric DLT framework, its benchmarking tool Caliper, and a dedicated test bed, where network properties such as latency or packet loss can be artificially influenced. Our experiments show that the validation of the transactions in a DLT-based system is the main contributor in the transaction latency. We also demonstrate that the properties of the communication network can influence the performance largely, even in the case where only one of the participants in the DLT system has poor network access.
When the enrollment services division at Central New Mexico Community College started looking at digital services for diplomas, transcripts, and other credentials, they were guided by the institution's strategic plan. One of the plan's priorities was to shift from college‐owned technology to student‐owned technology, said Feng Hou, chief information officer and chief digital learning officer.
There are many blockchain frameworks have been introduced to user, developer, and customer and they have to make a decision which one is most suitable for them in order for developing their applications. This paper describes an empirical research to benchmark the properties of frameworks in Hyperledger family. The purpose is to show the advantage & disadvantage of each framework. We apply the deeply study inside the framework and do the experiment to measure the properties as well as give literature and numerical review of each framework. Our results show the status of tested frameworks and do not demonstrate how to employ the framework as well as apply to the detail application. The main contribution of this paper is a statistical analysis of the effectiveness of Hyperledger frameworks as a tool for developer to develop their applications.
In recent years, blockchains have obtained so much attention from researchers, engineers, and institutions; and the implementation of blockchains has started to revive a large number of applications ranging from e-finance, e-healthcare, smart home, Internet of Things, social security, logistics and so forth. In the literature on blockchains, it is found that most articles focused on their engineering implementation, while little attention has been devoted to the exploration of theoretical aspects of the system; however, the existing work is limited to model the mining process only. In this paper, a queuing theory-based model is proposed for understanding the working and theoretical aspects of the blockchain. We validate our proposed model using the actual statistics of two popular cryptocurrencies, Bitcoin and Ethereum, by running simulations for two months of transactions. The obtained performance measures parameters such as the Number of Transactions per block, Mining Time of Each Block, System Throughput, Memorypool count, Waiting Time in Memorypool, Number of Unconfirmed Transactions in the Whole System, Total Number of Transactions, and Number of Generated Blocks; these values are compared with actual statistics. It was found that the results gained from our proposed model are in good agreement with actual statistics. Although the simulation in this paper presents the modeling of blockchain-based cryptocurrencies only, the proposed model can be used to represent a wide range of blockchain-based systems.
The blockchain is one of the most interesting technologies developed in recent years. Blockchain is a ledger, a register, a decentralized and public shared database, reachable by accessing a peer-to-peer network. Each unit of the register represents a block. The blocks are linked together in the same order in which they were created and are connected using cryptographic algorithms that make them and the information stored therein not modifiable. \nSoftware development needs to be supported by architectural models or blockchain oriented meta-models. The introduction of smart contracts, small computer programs stored inside the Ethereum blockchain, modifies the typical software engineering methodologies. The distributed applications developed on blockchain technologies, can in fact follow rules different from used for the development of the normal centralized applications. The blockchain is instead based on a totally different assumption: the information stored on the blockchain and therefore the smart contracts can not be modified or deleted without compromising the integrity of the blockchain itself. Moreover the smart contracts run in an isolated environment and their results must be the same whatever node they run in. They cannot access the external world that changes with time, but can access and send messages to the blockchain itself that is immutable. \nSuch an innovative context entails new challenges in software engineering. Greater emphasis on specific security and testing practices, new development tools, specific modeling languages and new metrics to evaluate software quality are needed. These new metrics are required to measure complexity, communication, decentralized systems, but also resource consumption (e.g. the so-called gas in the ethereum system). \nIn this scenario Agile methodologies, that are suited to system whose requirements are not completely understood, or tend to change, could be a good strategy of software development for blockchain applications. Some of the characteristics of the Agile methodologies are in fact present in decentralized applications (DApps). \nOne of the most interesting applications based on blockchain are the Initial Coin Offerings (ICOs). An ICO is an innovative way to raise funds and launch a startup. It is also an opportunity to take part in a project, or in a DAO (Decentralized Autonomous Organization). \nThis fund-raising tool contains however some critical issues, such as the use of tokens that have no intrinsic value and do not generate direct liquidity, and the role of investors in the startup’s management. The Lean software development, an approach that maximizes the value given to the customer, and aims to eliminate waste and optimize across organizations, could be helpful to face these critical aspects. \nThe ICOs and, more generally the decentralized applications are based on smart contracts. Considering the technological break through introduced by blockchain it is important to know characteristics and measures and quality parameters of the development process and its phases, as well as metrics to help ensure that the development process is under control to meet the product’s quality goals. This thesis analyzes the software development process of blockchain-based applications. In particular this work analyzes the following aspects. \n• Investigating software engineering activities related to ICOs, recognize the ICOs developed using Agile methods and make a comparison between the characteristics of ICOs and those of Agile ICOs. \n• Evaluating the lean startup approach as a methodology for the implementation of an ICO. \n• Analizyng smart contracts deployed on the Ethereum blockchain relatively to smart contracts features, their interaction with the blockchain, the role of the development community, and the source code characteristics.
Provably neutral clouds are undoubtedly a viable solution to blockchain scaling. By optimizing the transport layer, not only can the throughput be fundamentally scaled up, but the latency could be dramatically reduced. Indeed, the latency distribution in today’s data centers is already biased toward microsecond timescales for most of the flows, with millisecond timescales residing only at the tail of the distribution. There is no reason why a BDN point of presence would not be able to achieve a similar performance. Adding dedicated optical infrastructure among such BDN points of presence would further alleviate throughput and reduce latency, creating the backbone of an advanced BDN. The key to this vision, however, lies in establishing trust by the blockchain ecosystem into the underlying networking infrastructure. This, in turn, is achieved by decoupling authority from infrastructure via a provably neutral network design.
Contemporary software deployments rely on cloud-based package managers for installation, where existing packages are installed on demand from remote code repositories. Usually frameworks or common utilities, packages increase the code reusability within the ecosystem, whilst keeping the code base small. However, disruptions in the package management services can potentially affect development and deployment workflows. Furthermore, cloud package managers have arguably an ambiguous ownership model and offer limited visibility of packages to the users. This work describes the development of a blockchain-based package control system which is decentralised, reliable, and transparent. Blockchain nodes are installed within the distributed infrastructure to provide immutability, and then a dependency graph is constructed with the help of smart contracts to trace the software provenance. Our system has been successfully tested with 4338 packages from NPM, 950 out of which are the top depended-upon packages.
This article mainly introduces the application program of blockchain technology in the evaluation of students' professional ability. Through K-means clustering algorithm, students' academic performance and academic achievements in school, training, competitions, practice and other activities outside school are analyzed, in order to objectively and effectively evaluate the students' professional ability, which provides reasonable advice for student employment. In the system design, the blockchain technology is applied to the student ability evaluation system. The blockchain technology provides distributed storage and is nondestructive and traceability, so as to achieve the overall monitoring of students' professional ability evaluation process, student assessment data can be traced and student learning credit can be increased anytime anywhere. This paper presents a design scheme of the student ability evaluation system based on blockchain technology, which includes a student ability analysis method based on clustering algorithm and an overall system architecture diagram based on blockchain technology, which provides possibilities for creating an ecosystem of student ability evaluation for the future.
With the widespread of Bitcoin, blockchain has been focused by researchers from many fields, such as digital cryptocurrencies, finance security exchange, decentralized trade platform and so on. However, the operation efficiency (about 10min/per block) has limited its practical application except of Bitcoin. In this paper, we conduct further research based on the existing hybrid blockchain architectures, say N + X Hybrid Blockchain, which may significantly improve blockchain efficiency with the negligible cost of security. Moreover, we gave an evaluation model for the feedback process of nodes in the N+X Hybrid Blockchain and obtained optimal strategies. For the application of Energy Internet (EI), we proposed a scheduling mechanism based on the above evaluation model, and given an algorithm to implement it.
Marcela Tuler de Oliveira, Gabriel R. Carrara, Natália C. Fernandes, Célio Albuquerque · 7 authors
The blockchain is currently under the spotlight of trending technologies. It adds security to private applications in several areas of knowledge, and its versatility results in the development of multiple frameworks to meet the requirements of each application. Thus, it is a key challenge to ensure that blockchain frameworks provide security, access control, and high performance to applications. In this paper, we evaluate two frameworks for blockchain development, Parity, and Multichain, which provide configuration and permission flexibility. Our evaluation is a comprehensive comparison between the frameworks, focusing on the analysis of transaction-validation time, transaction-mining time, transaction-seek time and block-seek time. To this end, we deploy peer-to-peer private permissioned networks, in which the frameworks generate the blockchain applications. For each framework, we provide a realistic workload, based on the distribution of probability of interarrival time of transactions on the Bitcoin network. The results show that each framework stands out under specific criteria, and their design decisions imply restrictions on features that are critical for creating secure and efficient blockchain applications.
Maximiliano Geier, Claudio J. Tessone, Marco Vanotti, Silvio Vilerino · 6 authors
Large-scale distributed systems are becoming more widespread and, at the same time, their sizes grow day by day. In this type of systems, the adoption of blockchains is gaining particular traction for data storage in a secure and distributed manner. Nevertheless, design and testing of new protocols and features face the challenge of determining whether the proposed modifications would actually improve the system as expected. In the case of existing cryptocurrency systems, building an evaluation platform poses additional difficulties due to the resource-consuming nature of the associated processes. In this paper, we propose a novel methodology that relies on container-based network emulation to create scalable local testbeds in which Proof-of-Work-based blockchain systems can be evaluated. Using one of the mainstream Ethereum clients, we replaced the mining algorithm with a simulation model built upon the statistical characteristics of the mining process and instrumented the client to capture relevant network events. These events are used to create an offline reconstruction of the global view of the blockchain and all forking events, and to completely characterize the working conditions under arbitrary setups. Based on the versatility and scalability of our platform, we are able to test several network scenarios of increasing size in which we analyze the incidence of the target time in the generation of contradictory views of the blockchain (i.e. forks). We show that even using a limited testbed constituted by just commodity hardware, it is possible to use our platform to study the dynamics of blockchain-based systems up to hundreds of nodes.
Roberto Tonelli, Maria Ilaria Lunesu, Andrea Pinna, Davide Taibi · 5 authors
Blockchain technologies and smart contracts are becoming mainstream research fields in computer science and researchers are continuously investigating new frontiers for new applications. Likewise, microservices are getting more and more popular in the latest years thanks to their properties, that allow teams to slice existing information systems into small and independent services that can be developed independently by different teams. A symmetric paradigm applies to smart contracts as well, which represent well defined, usually isolated, executable programs, typically implementing simple and autonomous tasks with a well defined purpose, which can be assumed as services provided by the Contract. In this work we analyze a concrete case study where the microservices architecture environment is replicated and implemented through an equivalent set of smart contracts, showing for the first time the feasibility of implementing a microservices-based system with smart contracts and how the two innovative paradigms match together. Results show that it is possible to implement a simple microservices-based system with smart contracts maintaining the same set of functionalities and results. The result could be highly beneficial in contexts such as smart voting, where not only the data integrity is fundamental but also the source code executed must be trustable.
Ethereum clients execute transactions in a sequential order prescribed by the consensus protocol. This is a safe and conservative approach to blockchain transaction processing which forgoes running transactions in parallel even when doing so would be beneficial and safe, e.g., when there is no intersection in the sets of accounts that the transactions read or modify. In this work we study the degree of transaction parallelizability and present results from three different simulations using real Ethereum transaction data. Our simulations demonstrate that notable gains are achievable with parallelization, and suggest that the potential for parallelizability improves as transaction rates increase.
The Blockchain technology was initially adopted to implement various cryptocurrencies. Currently, Blockchain is foreseen as a general purpose technology with a huge potential in many areas. Blockchain-based applications have inherent characteristics like authenticity, immutability and consensus. Beyond that, records stored on Blockchain ledger can be accessed any time and from any location. Blockchain has a great potential for managing and maintaining educational records. This paper presents a Blockchain-based Educational Record Repository (BcER2) that manages and distributes educational assets for academic and industry professionals. The BcER2 system allows educational records like e-diplomas and e-certificates to be securely and seamless transferred, shared and distributed by parties.
Blockchain's decentralized and consensus mechanism has attracted lots of applications, such as IoT devices. Blockchain maintains a linked list of blocks and grows by mining new blocks. However, the Blockchain mining consumes huge computation resource and energy, which is unacceptable for resource-limited embedded devices. This paper for the first time presents a ReRAM-based processing-in-memory architecture for Blockchain mining, called Re-Mining. Re-Mining includes a message schedule module and a SHA computation module. The modules are composed of several basic ReRAM-based logic operations units, such as ROR, RSF and XOR. Re-Mining further designs intra-transaction and inter-transaction parallel mechanisms to accelerate the Blockchain mining. Simulation results show that the proposed Re-Mining architecture outperforms CPU-based and GPU-based implementations significantly.
Blockchains are distributed secure ledgers to which transactions are issued
continuously and each block is tightly coupled to its predecessors.
Permissioned blockchains place special emphasis on transactions throughput. In
this paper we present TOY, which leverages the iterative nature of blockchains
in order to improve their throughput in optimistic execution scenarios. TOY
trades latency for throughput in the sense that in TOY the last f+1 blocks of
each node's blockchain are considered tentative, i.e., they may be rescinded in
case one of the last f+1 blocks proposers was Byzantine. Yet, when optimistic
assumptions are met, a new block is decided in each communication step, which
consists of a proposer that sends only its proposal and all other participants
are sending a single bit each. Our performance study demonstrates that in a
single Amazon data-center, TOY running on 10 mid-range Amazon nodes obtains a
throughput of up to 160K transactions per second for (typical Bitcoin size) 512
bytes transactions. In a 10 nodes Amazon geo-distributed setting with 512 bytes
transactions, TOY obtains a throughput of 30K transactions per second.
A comprehensive empirical study is performed to measure the performance of a Blockchain-based Certi cation Storage System in Hyperledger Fabric. This work is based on a proof of concept in the aviation industry and fol- lows a Technical Risk & E cacy evaluation strategy to determine the utility derived from the use of the artefact. Relevant tuning parameters for per- formance and scalability as well as bottlenecks are identi ed. The impact of con guration parameters such as blocksize, transaction arrival rate and number of concurrent users on the systems performance is investigated. Ob- servations show that demands at throughput above system limits lead to transaction failures. Contributed are a repeatable process to performance sensitivity analysis and recommendations for con guring a Blockchain-based Certi cation Storage System for stable but high performance. The results can be used as a basis for optimizing the performance of similar systems.
Alexander Mikroyannidis, Allan Third, John Domingue
Blockchain technology provides a decentralised peer-to-peer infrastructure, supporting openness, transparency, accountability, identity management and trust. As such, the Blockchain has the potential to revolutionise online education in a number of ways. Blockchain technology offers opportunities to thoroughly rethink how we find educational content and training services online, how we register and pay for them, as well as how we get accredited for what we have learned and how this accreditation affects our career trajectory. This paper explores the different aspects of online education that are affected by this new paradigm. In particular, we investigate the different scenarios where the use of Blockchain technology can make online education more open and decentralised, while placing learners in control of their learning process and its associated data. Additionally, we discuss various approaches to the Semantic Blockchain and the applications of these approaches on online education.
Systems that use blockchain technology to improve the know-your-customer (KYC) process have only been proposed at a conceptual level and all share certain attributes that make their adoption very difficult. We propose and program a blockchain-based system that reduces and shares out among the financial institutions (FIs) that work with a customer the costs of the KYC process and also makes it possible for FIs to dynamically update information related to customers and disseminates this information among participating FIs. Additionally, our system addresses some of the attributes that hinder the adoption of previously proposed solutions by FIs. The result is a stand-alone solution that reduces the cost of the KYC process without requiring any central instance to store the customer's data, and in which FIs share the initial costs of the KYC process as well as the running costs of keeping the information about customers up to date.
The market for invoice financing has been steadily growing in the last few years and has been the third financing market in size in 2016. Most solutions in this field are based on private platforms and even the new proposals based on blockchain are mostly adopting a private, permissioned blockchain. In this paper, we propose an idea based on a public blockchain that allows both fully open and group-restricted auctioning of invoices. Furthermore, our proposal introduces a reputation system that is based on the past behavior of entities, as it is photographed by the public blockchain, to allow insurance companies modulate the cost of the insurance contracts they offer. This combination guarantees the complete transparency and tamperproof-ness of a public blockchain, while it allows reducing insurance costs and fraud possibilities.