Bruno W. França, Sophie Radermacher, Reto Trinkler
Katal is a new blockchain that provides a standard way to build and deploy decentralized financial applications. It brings together all the components necessary for the backend of a financial application, namely: a high-performance consensus, an authenticated data feed system, a standard for financial contracts and connectivity to the rest of the blockchain ecosystem. Katal enables and simplifies the creation of financial services that are non-custodial, trustless, fast, convenient and interoperable.
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.
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.
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.
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.
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.
Yackolley Amoussou-Guenou, Antonella Del Pozzo, Maria Potop-Butucaru, Sara Tucci-Pergiovanni
Committee-based blockchains are among the most popular alternatives of proof-of-work based blockchains, such as Bitcoin. They provide strong consistency (no fork) under classical assumptions, and avoid using energy-consuming mechanisms to add new blocks in the blockchain. For each block, these blockchains use a committee that executes Byzantine-fault tolerant distributed consensus to decide the next block they will add in the blockchain. Unlike Bitcoin, where there is only one creator per block, in committee-based blockchain any block is cooperatively created. In order to incentivize committee members to participate in the creation of new blocks, rewarding schemes have to be designed. In this paper, we study the fairness of rewarding in committee-based blockchains and we provide necessary and sufficient conditions on the system communication under which it is possible to have a fair reward mechanism.
Jan 1, 2019·Proceedings of the ... Annual Hawaii International Conference on System Sciences/Proceedings of the Annual Hawaii International Conference on System Sciences
Leonardo Maria De Rossi, Nico Abbatemarco, Gianluca Salviotti
The increasingly need for companies to keep a high level of synchronization globally and the advent of new technologies are pushing more and more to move decision-making and operational power from the centre of organizations to their edges. The blockchain could be the key technology to make this change possible. However, there is no bridge yet capable of shortening the still long distance between this new technological phenomenon and today's business realities. Our work aims precisely at this goal; we propose a framework of blockchain models to help practitioners understanding and potentially implement new solutions based on this technological paradigm. In particular, we have developed an ontology that helps to identify and clarify in detail what are the concepts and structures revolving around this technology, and built a continuum of blockchain architectural solutions, ranging from a classic centralized IT architecture to one completely distributed within a public ecosystem.
Katharina Zeuch, Kai Hendrik Wöhnert, Volker Skwarek
Due to increasing security requirements e. g. for transaction based smart-x-technologies in distributed systems, blockchain technologies are predestined for secure data exchange and keeping in distributed systems. Although the underlying principle of almost every blockchain is the Byzantine fault tolerance (BFT), its implementation differs significantly between the technologies so that migration or interoperability between systems is nearly impossible. Additionally, this missing interoperability also reduces the chance for scalability between different extents of implementation as there is usually not a one-size-fits-all-blockchain: Different technologies have their advantages for different systems. Therefore scalability and interoperability are tightly coupled. As a basis for further research on and the derivation of generally scalable and interoperable architectures of blockchains, current technologies have to be made comparable and interoperability criteria have to be developed. This paper analyses current literature and introduces technical criteria for the comparison of blockchainand distributed ledger technologies (BC/DLT).With a list of eleven criteria popular BC/DLTs such as Bitcoin, Ethereum, Hyperledger Fabric, Ripple and Corda are compared regarding general features.
Jan 1, 2019·Proceedings of the ... Annual Hawaii International Conference on System Sciences/Proceedings of the Annual Hawaii International Conference on System Sciences
With the advent of blockchain technology, some management tasks of IoT networks can be moved from central systems to distributed validation authorities. Cloud-centric blockchain implementations for IoT have shown satisfactory performance. However, some features of blockchain are not necessary for IoT. For instance, a competitive consensus. This research presents the idea of customizing and encapsulating the features of blockchain into software-defined components to host them on edge devices. Thus, blockchain resources can be provisioned by edge devices (e-miners) working together closer to the things layer in a cooperative manner. This research uses Edison SoC as e-miners to test the software-defined blockchain components.
Both blockchain technologies and cloud computing are contemporary emerging technologies. While the application of Blockchain technologies is being spread beyond cryptocurrency, cloud computing is also seeing a paradigm shift to meet the needs of the 4th industrial revolution (Industry 4.0). New technological ad-vancement, especially by the fusion of these two, such as Blockchain-as-a-Service (BaaS), is considered to be able to significantly generate values to the en-terprises. This article surveys the current status of BaaS in terms of technological development, applications, market potentials and so forth. An evaluative judge-ment, comparing amongst various BaaS platforms, has been presented, along with the trajectory of adoption, challenges and risk factors. Finally, the study suggests standardisation of available BaaS platforms.
To address the large amount of energy wasted by blockchains, we propose a decentralized consensus protocol for blockchains in which the computation can be used to search for good approximate solutions to any optimization problem. Our protocol allows the wasted energy to be used for finding approximate solutions to problems submitted by any nodes~(called clients). Our protocol works in a similar way to proof-of-work, and it makes nodes evaluate a large number of solution candidates to add a new block to the chain. A client provides a search program that implements any search algorithm that finds a good solution by evaluating a large number of solution candidates. The node that finds the best approximate solution is rewarded by the client. Our analysis shows that the probability of a fork and the variance in the block time with our protocol are lower than those in proof-of-work.
Research in the field of blockchain technology and applications is increasing at a fast pace. Although the Bitcoin whitepaper by Nakamoto is already ten years old, the field can still be seen as immature and at an early stage. Current research in this area is lacking a commonly shared knowledge and consensus about terms used to describe the technology and its properties. At the same time this research is challenging fundamental aspects of the Bitcoin core concept. It has to be questioned whether all of these new approaches still adequately could be described as blockchain technology. We propose to use the term Decentralized Consensus Technology as a general category instead. Decentralized Consensus Technology consists of decentralized ledger and non-ledger technologies. Blockchain technology in turn is only one of multiple implementations of the Decentralized Ledger Technology. Furthermore, we identified three main characteristics of Decentralized Consensus Technology: decentralization, trustlessness and ability to eventually reach consensus. Depending on the use case of the specific implementation the following additional properties have to be considered: privacy, participation incentive, irreversibility and immutability, operation purpose, confirmation time, transaction costs, ability to externalize transactions and computations and scalability possibilities.
Santiago Bragagnolo, Matteo Marra, Guillermo Polito, Elisa Gonzalez Boix
Analysing the blockchain is becoming more and more relevant for detecting attacks and frauds on cryptocurrency exchanges and smart contract activations. However, this is a challenging task due to the continuous growth of the blockchain. For example, in early 2017 Ethereum was estimated to contain approximately 300GB of data [1], a number that keeps growing day after day. In order to analyse such ever-growing amount of data, this paper argues that blockchain analysis should be treated as a novel type of application for Big Data platforms. In this paper we explore the application of parallelization techniques from the Big Data domain, in particular Map/Reduce, to extract and analyse information from the blockchain. We show that our approach significantly improves the index generation by 7.77 times, with a setup of 20 worker nodes, 1 Ethereum node and 1 Database node. We also share our findings of our massively parallel setup for querying Ethereum in terms of architecture and the bottlenecks. This should help researchers setup similar infrastructures for analysing the blockchain in the future.
Jan 1, 2019·Proceedings of the ... Annual Hawaii International Conference on System Sciences/Proceedings of the Annual Hawaii International Conference on System Sciences
Blockchain is a decentralized digital ledger that challenges existing business models and theories by shifting the trust from institutions towards algorithms. However, the number of successfully developed blockchain-based systems remains low. This points towards a research gap between blockchain applications and technical blockchain characteristics. We answer the research question: What application areas fit blockchains with what technical characteristics? We develop a taxonomy, which comprises six blockchain application areas that are classified across eight technical dimensions. We demonstrate the utility of the taxonomy on ninety-nine blockchain-based systems. We contribute to the scientific literature by delimiting blockchain application areas, identifying new technical dimensions, and linking application and technical knowledge on blockchain to guide development of blockchain-based systems. For practitioners, we present an overview of current blockchain-based systems.
An inclusive project is classified and alienated into several tasks where as task management is one of the foremost components of project management, since the roles and tasks assigned by the manager of this component to each employee working on a project. In scrupulous there are several ways to track the status of work and this monitoring is also required to find the efficiency of an individual and at the time of the annual and mid- term appraisal and all these monitoring records can be used to give qualifications to associates and employees. In this work, the authors have proposed a system along with the solution based on the ERC20 token which is identified as blockchain platform based on Ethereum in which they can implement Project Task Management which is tamper proof and as well as can track the assigned task of an employee on real time basis.