In the wake of the financial crisis of 2008, Bitcoin emerged as a radical new alternative to the fiat currencies of the traditional banking sector. Through the use of a novel kind of probabilistic consensus algorithm, Bitcoin proved it possible to guarantee the integrity of a digital currency by relying on network majority votes instead of trusted institutions. By showing that it was technically feasible to, at least to some extent, replace the entire banking sector with computers, many significant actors started asking what else this new technology could help automate. A subsequent, seemingly inevitable, wave of efforts produced a multitude of new distributed ledger systems, architectures and applications, all somehow attempting to leverage distributed consensus algorithms to replace trusted intermediaries, facilitating value ownership, transfer and regulation. In this thesis, we scrutinize distributed ledger technologies in terms of how they could help facilitate the digitization of contractual cooperation, especially in the context of the supply chain and manufacturing industries. Concretely, we consider them from three distinct technical perspectives, (1) performance, (2) interoperability and (3) integration. Voting systems, with or without probabilistic mechanisms, require significant time and resources to operate, for which reason it becomes relevant to investigate how the costs of running those systems can be mitigated. In particular, we consider how a blockchain, a form of distributed ledger, can be pruned to in order to reduce disk space requirements. Furthermore, no technical system part of a larger business is an island, but will have to be able to interoperate with other systems to maximize the opportunity for automation. For this reason, we also consider how transparent message translation between systems could be facilitated, as well as presenting a formalism for expressing the syntactic structure of message payloads. Finally, we propose a concrete architecture, the Exchange Network, that models contractual interactions as negotiations about token exchanges rather than as function invocations and state machine transitions, which we argue lowers the barrier to compatibility with conventional legal and business practices. Even if no more trusted institutions could be replaced by any forthcoming distributed ledger technologies, we believe contractual interactions becoming more digital would lead to an increased opportunity for using computers to monitor, assist or even directly participate in the negotiation, management and tracking of business agreements, which we see as more than enough to warrant the cost of further developing of the technology. Such computer involvement may not just save time and reduce costs, but could also enable new kinds of computer-driven economies. In the long run, this may enable new levels of resource optimization, and not just within large organizations, but also smaller companies, or even the homes of families and individuals.
Cryptocurrencies, blockchain technology and smart contracts could fundamentally change the way how financial products and financial services are implemented and operated. While many frameworks for implementing such blockchain applications already exist, these are usually implemented using languages either considered “fancy” today, like e.g. Go, or are traditionally used for system software, such as C++. On the other hand, the core business applications e.g. in financial services are typically implemented using enterprise platforms such as Java Enterprise Edition (EE) and/or COBOL. Therefore, to improve the integration of blockchain technology in such applications, in this paper we argue in favor of a legacy-friendly distributed ledger solution by introducing QWICSchain, an implementation build on web services using established open-source enterprise technologies such as Java EE and PostgreSQL. It supports the parallel execution of transactions on the blockchain and in existing legacy applications, thus enabling the blockchain-based modernization of existing IT infrastructures.
The significant growth and adoption of Internet of Things (IoT) solutions has led to tremendous increase in the generation of data. The need for high speed data processing has become very important to meet with the ever increasing volume and velocity of IoT data, due to the large scale and distributed nature of IoT infrastructure and networks. Present cloud based technologies are struggling to meet up with these needs for real time data processing in the midst of enormous amounts of data. The success of bitcoin has inspired more research in the application of Distributed ledger technologies in various domains. The decentralized nature of these platforms have enabled security and privacy of data in previous research and their architecture has a potential for enabling large scale decentralized data processing. In this paper, we identify some open areas of research in the use of distributed ledger technology and propose a framework for storing, analyzing and ensuring the security of large volumes of IoT data.
Hye-Young Paik, Xiwei Xu, H. M. N. Dilum Bandara, Sung Une Lee · 5 authors
In a blockchain-based system, data and the consensus-based process of recording and updating them over distributed nodes are central to enabling the trustless multi-party transactions. Thus, properly understanding what and how the data are stored and manipulated ultimately determines the degree of utility, performance, and cost of a blockchain-based application. While blockchains enhance the quality of the data by providing a transparent, immutable, and consistent data store, the technology also brings new challenges from a data management perspective. In this paper, we analyse blockchains from the viewpoint of a developer to highlight important concepts and considerations when incorporating a blockchain into a larger software system as a data store. The work aims to increase the level of understanding of blockchain technology as a data store and to promote a methodical approach in applying it to large software systems. First, we identify the common architectural layers of a typical software system with data stores and conceptualise each layer in blockchain terms. Second, we examine the placement and flow of data in blockchain-based applications. Third, we explore data administration aspects for blockchains, especially as a distributed data store. Fourth, we discuss the analytics of blockchain data and trustable data analytics enabled by blockchain. Lastly, we examine the data governance issues in blockchains in terms of privacy and quality assurance.
Jan 1, 2019·Proceedings of the ... Annual Hawaii International Conference on System Sciences/Proceedings of the Annual Hawaii International Conference on System Sciences
Taneli Hukkinen, Juri Mattila, Kari Smolander, Timo Seppälä · 5 authors
In recent years, information systems have not been largely evaluated by their operating costs, but mainly by their strategic benefit and competitive advantage. As blockchain-based decentralized applications become more commonplace, representing a shift towards fully consumption-based distributed computing, a new mode of thinking is required of developers, with meticulous attention to computational resource efficiency. This study improves on a blockchain application designed for conducting microtransactions of electricity in a nanogrid environment. By applying the design science research methodology, we improve the efficiency of the application’s smart contract by 11 %, with further improvement opportunities identified. Despite the results, we find the efficiency remains inadequate for public Ethereum deployment. From the optimization process, we extrapolate a set of general guidelines for optimizing the efficiency of Ethereum smart contracts in any application.
A purely peer-to-peer version of electronic cash would allow online payments to be sent directly from one party to another without going through a financial institution. Digital signatures provide part of the solution, but the main benefits are lost if a trusted third party is still required to prevent double-spending. We propose a solution to the double-spending problem using a peer-to-peer network. The network timestamps transactions by hashing them into an ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work. The longest chain not only serves as proof of the sequence of events witnessed, but proof that it came from the largest pool of CPU power. As long as a majority of CPU power is controlled by nodes that are not cooperating to attack the network, they'll generate the longest chain and outpace attackers. The network itself requires minimal structure. Messages are broadcast on a best effort basis, and nodes can leave and rejoin the network at will, accepting the longest proof-of-work chain as proof of what happened while they were gone.
Weilin Zheng, Zibin Zheng, Xiangping Chen, Kemian Dai · 6 authors
Blockchain, originated from Bitcoin system, has drawn intense attention from the academic community because of its decentralization, persistency, anonymity and auditability. In the past decade, the blockchain technology has evolved and became viable for various applications beyond the domain of finance. However, due to the complexity of blockchain technology, it is usually difficult and costly for most developers or teams to build, maintain and monitor a blockchain network that supports their applications. Most common developers or teams are unable to ensure the reliability and security of the blockchain system, which to a certain extent affects the quality of their applications. In this paper, we develop a BaaS platform called NutBaaS, which provides blockchain service over cloud computing environments, such as network deployment and system monitoring, smart contracts analysis and testing. Based on these services, developers can focus on the business code to explore how to apply blockchain technology more appropriately to their business scenarios, without bothering to maintain and monitor the system.
Blockchain is defined as a distributed ledger technology that can implement financial models. An improved blockchain provides a democratic virtual economic system (DVES) that can verify payments, reach consensus, and store encrypted data in virtual economic systems. In this paper, we review the latest progress and possibilities in improved blockchain with respect to openness, data security, and scalability. This paper outlines the challenges of value, existence, and status (VES) and the state-of-the-art solutions for improved blockchain. Then, this paper discusses the VES in terms of distributed energy, ownership certification, infrastructure, and other fields. More importantly, it analyzed the importance of scale out, which can be a key enabler to solve the main practical problems in constructing DVES.
This paper presents a stochastic model for block arrival times based on the difficulty retargeting rule used in Bitcoin, as well as other proof-of-work blockchains. Unlike some previous work, this paper explicitly models the difficulty target as a random variable which is a function of the previous block arrival times and affecting the block times in the next retargeting period. An explicit marginal distribution is derived for the time between successive blocks (the blocktime), while allowing for randomly changing difficulty. This paper also aims to serve as an introduction to Bitcoin and proof-of-work blockchains for the controls community, focusing on the difficulty retargeting procedure used in Bitcoin.
Today's commercial model for edge computing services consists in lightweight devices at the network edge connected through the Internet to remote cloud data centers. Microclouds are an alternative vision of edge computing, where the cloud infrastructure runs at the network edge leveraging decentralized resource contributions of a community. But current attempts to build such microclouds lack a collaborative governance system to operate successfully. In this paper we discuss the opportunity to implement with blockchain technologies key services to enable the decentralized collaborative governance of microclouds. A multiagent approach could further contribute to improve the efficiency in the decision making in the collaborative governance service.
Blockchain is one of the most heavily invested technologies in recent years. Due to its tamper-proof and decentralization properties, blockchain has become an ideal utility for data storage that is applicable in many real world industrial scenarios. One important scenario is web log, which is treated as sources of technical significance and commercial revenues in major internet companies. In this paper, we illustrate our design of a web log storage system based on HyperLedger. HyperLedger yields higher throughput and lower latency compared with other blockchain systems. Alongside its efficiency advantages., HyperLeger is a permissioned blockchain, which is an ideal fit for enterprise software design scenario.
Reports on the development of Open and Interoperable Distributed Ledger Technology/Blockchain standards. Discusses how these standards drive global blockchain adoption and take development of the technology ecosystem to the next level. The field of blockchain or distributed ledger is growing rapidly. The lack of consensus on definitions, implementation, management, and core attributes is driving the need for standardization. Blockchain is often confused with cryptocurrencies like Bitcoin or Ethereum, but the potential applications of this technology in diverse fields, such as smart contracts, buying and selling energy, and so much more, make distributed ledger technologies one of the high-potential technologies for the future.
Nov 1, 2018·B. Varghese et al., "Realizing Edge Marketplaces: Challenges and Opportunities," in IEEE Cloud Computing, vol. 5, no. 6, pp. 9-20, Nov./Dec. 2018
Blesson Varghese, Massimo Villari, Omer Rana, Philip James · 7 authors
The edge of the network has the potential to host services for supporting a variety of user applications, ranging in complexity from data preprocessing, image and video rendering, and interactive gaming, to embedded systems in autonomous cars and built environments. However, the computational and data resources over which such services are hosted, and the actors that interact with these services, have an intermittent availability and access profile, introducing significant risk for user applications that must rely on them. This article investigates the development of an edge marketplace, which is able to support multiple providers for offering services at the network edge, and to enable demand supply for influencing the operation of such a marketplace. Resilience, cost, and quality of service and experience will subsequently enable such a marketplace to adapt its services over time. This article also describes how distributed-ledger technologies (such as blockchains) provide a promising approach to support the operation of such a marketplace and regulate its behavior (such as the GDPR in Europe) and operation. Two application scenarios provide context for the discussion of how such a marketplace would function and be utilized in practice.
Financial settlement systems have long depended on batch-oriented processing pipelines that introduce substantial operational latency, delayed reconciliation cycles, and significant infrastructure overhead, limiting their ability to support increasingly real-time financial ecosystems. With the rapid growth of digital payments, algorithmic trading, and instantaneous fund transfers, financial institutions now require settlement architectures capable of sustaining high throughput, low-latency execution while ensuring correctness, durability, auditability, and strict regulatory compliance. This paper proposes a fully streaming-based settlement architecture built on Apache Kafka Streams, which provides distributed, stateful stream processing with exactly-once semantics, deterministic event ordering, and fault-tolerant recovery, combined with Apache Cassandra as a linearly scalable, highly available distributed state store for ledger materialization and durable transaction history. We outline essential design patterns such as idempotent event handling, monotonic ordering within partitions, ledger versioning strategies, and continuous reconciliation pipelines and examine how these patterns have been validated through publicly available prototypes and industrial implementations across the financial sector. Experimental findings demonstrate that integrating Kafka Streams with Cassandra enables near-real-time settlement processing with millisecond-range end-to-end latency and predictable fault recovery while preserving strong application-level consistency, ultimately offering a resilient and future-ready foundation for modern financial settlement infrastructures.
Ankur Sharma, Felix Schuhknecht, Divya Agrawal, Jens Dittrich
Within the last few years, a countless number of blockchain systems have emerged on the market, each one claiming to revolutionize the way of distributed transaction processing in one way or the other. Many blockchain features, such as byzantine fault tolerance (BFT), are indeed valuable additions in modern environments. However, despite all the hype around the technology, many of the challenges that blockchain systems have to face are fundamental transaction management problems. These are largely shared with traditional database systems, which have been around for decades already. These similarities become especially visible for systems, that blur the lines between blockchain systems and classical database systems. A great example of this is Hyperledger Fabric, an open-source permissioned blockchain system under development by IBM. By having a relaxed view on BFT, the transaction pipeline of Fabric highly resembles the workflow of classical distributed databases systems. This raises two questions: (1) Which conceptual similarities and differences do actually exist between a system such as Fabric and a classical distributed database system? (2) Is it possible to improve on the performance of Fabric by transitioning technology from the database world to blockchains and thus blurring the lines between these two types of systems even further? To tackle these questions, we first explore Fabric from the perspective of database research, where we observe weaknesses in the transaction pipeline. We then solve these issues by transitioning well-understood database concepts to Fabric, namely transaction reordering as well as early transaction abort. Our experimental evaluation shows that our improved version Fabric++ significantly increases the throughput of successful transactions over the vanilla version by up to a factor of 3x.
Simona Ibba, Andrea Pinna, Maria Ilaria Lunesu, Michele Marchesi · 5 authors
An ICO (Initial Coin Offering) is an innovative way to fund projects based on blockchain. The funding is based on the selling of tokens by means of decentralized applications called smart contracts written in Solidity, a programming language specific for Ethereum blockchain. The ICOs work in a volatile context and it is crucial that the team is capable of handling constant changes. The Agile methods, proven practices enabling to develop software in presence of changing requirements, could be a means for managing uncertainty. The main goals of this work are to understand software engineering activities related to ICOs, recognize the ICOs developed using Agile methods, and make a comparison between ICOs and Agile ICOs. In addition, we perform a deeper analysis of Agile ICOs concerning project planning, software development, and code features. Our work shows that the roles of the people involved in an ICO can be compared to the typical roles of the SCRUM methodology. The majority of Agile ICOs use tool of testing before storing smart contract on blockchain. Finally, the application of volumetric and complexity software metrics shows that the files of Agile ICOs is on average shorter and less complex than in other smart contracts.
Sang‐Min Choi, Jiho Park, Quan Nguyen, André Cronje
We describe \emph{Fantom}, a framework for asynchronous distributed systems. \emph{Fantom} is based on the Lachesis Protocol~\cite{lachesis01}, which uses asynchronous event transmission for practical Byzantine fault tolerance (pBFT) to create a leaderless, scalable, asynchronous Directed Acyclic Graph (DAG). We further optimize the \emph{Lachesis Protocol} by introducing a permission-less network for dynamic participation. Root selection cost is further optimized by the introduction of an n-row flag table, as well as optimizing path selection by introducing domination relationships. We propose an alternative framework for distributed ledgers, based on asynchronous partially ordered sets with logical time ordering instead of blockchains. This paper builds upon the original proposed family of \emph{Lachesis-class} consensus protocols. We formalize our proofs into a model that can be applied to abstract asynchronous distributed system.
Cryptocurrencies and their foundation technology, the Blockchain, are reshaping finance and economics, allowing a decentralized approach enabling trusted applications with no trusted counterpart. More recently, the Blockchain and the programs running on it, called Smart Contracts, are also finding more and more applications in all fields requiring trust and sound certifications. Some people have come to the point of saying that the "Blockchain revolution" can be compared to that of the Internet and the Web in their early days. As a result, all the software development revolving around the Blockchain technology is growing at a staggering rate. The feeling of many software engineers about such huge interest in Blockchain technologies is that of unruled and hurried software development, a sort of competition on a first-come-first-served basis which does not assure neither software quality, nor that the basic concepts of software engineering are taken into account. This paper tries to cope with this issue, proposing a software development process to gather the requirement, analyze, design, develop, test and deploy Blockchain applications. The process is based on several Agile practices, such as User Stories and iterative and incremental development based on them. However, it makes also use of more formal notations, such as some UML diagrams describing the design of the system, with additions to represent specific concepts found in Blockchain development. The method is described in good detail, and an example is given to show how it works.
The Bitcoin protocol is a significant milestone in the history of money. However, its adoption is currently constrained by the transaction limits of the system. As the chief problem of blockchain technology, the scaling issue has attracted many valuable solutions both on-chain and off-chain. In this paper, our goal is to explore the notion of unspent transaction outputs (UTXOs) to propose an augmented Bitcoin protocol that can scale gracefully. Our proposal aims to increase the transaction throughput by partitioning the UTXO space and splitting the blockchain. In addition, a new type of Bitcoin node is introduced to preserve the capability to run validating nodes in low-bandwidth environments, despite the increased transaction throughput.
Blockchain platforms such as Ethereum and several others execute complex transactions in blocks through user-defined scripts known as smart contracts. Normally, a block of the chain consists of multiple transactions of smart contracts which are added by a miner. To append a correct block into the blockchain, miners execute these transactions of smart contracts sequentially. Later the validators serially re-execute the smart contract transactions of the block. If the validators agree with the final state of the block as recorded by the miner, then the block is said to be validated. It is then added to the blockchain using a consensus protocol. In Ethereum and other blockchains that support cryptocurrencies, a miner gets an incentive every time such a valid block successfully added to the blockchain. In most of the current day blockchains the miners and validators execute the smart contract transactions serially. In the current era of multi-core processors, by employing the serial execution of the transactions, the miners and validators fail to utilize the cores properly and as a result, have poor throughput. By adding concurrency to smart contracts execution, we can achieve better efficiency and higher throughput. In this paper, we develop an efficient framework to execute the smart contract transactions concurrently using optimistic Software Transactional Memory systems (STMs). Miners execute smart contract transactions concurrently using multi-threading to generate the final state of blockchain. STM is used to take care of synchronization issues among the transactions and ensure atomicity. Now when the validators also execute the transactions (as a part of validation) concurrently using multi-threading, then the validators may get a different final state depending on the order of execution of conflicting transactions. To avoid this, the miners also generate a block graph of the transactions during the concurrent execution and store it in the block. This graph captures the conflict relations among the transactions and is generated concurrently as the transactions are executed by different threads. The miner proposes a block which consists of set of transactions, block graph, hash of the previous block, and final state of each shared data-objects. Later, the validators re-execute the same smart contract transactions concurrently and deterministically with the help of block graph given by the miner to verify the final state. If the validation is successful then proposed block appended into the blockchain and miner gets incentive otherwise discard the proposed block. We execute the smart contract transactions concurrently using Basic Time stamp Ordering (BTO) and Multi-Version Time stamp Ordering (MVTO) protocols as optimistic STMs. BTO and MVTO miner achieves 3.6x and 3.7x average speedups over serial miner respectively. Along with, BTO and MVTO validator outperform average 40.8x and 47.1x than serial validator respectively.
It is commonly believed that blockchain is a revolutionary technology for doing business on the Internet. Blockchain is a decentralized, distributed database or ledger of records. It ensures that the records are tamper-proof but publicly readable. Blockchain platforms such as Ethereum [3] and several others execute complex transactions in blocks through user-defined scripts known as smart contracts. Normally, a block of the chain consists of multiple transactions of smart contracts which are added by a miner. To append a correct block into the blockchain, miners execute these transactions of smart contracts sequentially. Later the validators serially re-execute the smart contract transactions of the block. If the validators agree with final state of the blocks as recorded by the miner, then the block is said to be valid and added to the blockchain using a consensus protocol.
Marco Conoscenti, Antonio Vetrò, Juan Carlos De Martin, Federico Spini
The Lightning Network (LN) is one of the most promising off-chain scaling solutions for Bitcoin, as it enables off-chain payments which are not subject to the well-known blockchain scalability limit. In this work, we introduce CLoTH, a simulator for HTLC payment networks (of which LN is the best working example). It simulates input-defined payments on an input-defined HTLC network and produces performance measures in terms of payment-related statistics (such as time to complete payments and probability of payment failure). CLoTH helps to predict issues and obstacles that might emerge in the development stages of an HTLC payment network and to estimate the effects of an optimisation action before deploying it. We conducted simulations on a recent snapshot of the HTLC payment network of LN. These simulations allowed us to identify network and payments configurations for which a payment is more likely to fail than to succeed. We proposed viable solutions to avoid such configurations.
A wide range of services and applications can be improved and/or solved by\nusing distributed ledger technology (DLT). These services and applications have\nwidely varying quality of service (QoS) requirements. However, most existing\nDLT systems do not distinguish different QoS requirements, resulting in\nsignificant performance issues such as poor scalability and high cost. In this\nwork, we present vDLT -- a service-oriented blockchain system with\nvirtualization and decoupled management/control and execution. In vDLT,\nservices and applications are classified into different classes according to\ntheir QoS requirements, including confirmation latency, throughput, cost,\nsecurity, privacy, etc. This is a paradigm shift from the existing\n"blockchain-oriented" DLT systems to next generation "service-oriented" DLT\nsystems. Different QoS requirements are fulfilled by advanced schemes inspired\nby the development of the traditional Internet, including classification,\nqueuing, virtualization, resource allocation and orchestration, and\nhierarchical architecture. In addition, management/control and execution of\nsmart contracts are decoupled to support QoS provisioning, improve\ndecentralization, and facilitate evolution in vDLT. With virtualization,\ndifferent virtual DLT systems with widely varying characteristics can be\ndynamically created and operated to accommodate different services and\napplications.\n
In 2008, Satoshi Nakamoto famously invented bitcoin, and in his (or her, or their, or its) white paper sketched an approximate formula for the probability of a successful double spending attack by a dishonest party. This was corrected by Meni Rosenfeld, who, under more realistic assumptions, gave the exact probability (missing a foundational proof); and another formula (along with foundational proof), in terms of the Incomplete Beta function, was given later by Cyril Grunspan and Ricardo Pérez-Marco, that enabled them to derive an asymptotic formula for that quantity. Using Wilf-Zeilberger algorithmic proof theory, we continue in this vein and present a recurrence equation for the above-mentioned probability of success, that enables a very fast compilation of these probabilities. We next use this recurrence to derive (in algorithmic fashion) higher-order asymptotic formulas, extending the formula of Grunspan and Pérez-Marco who did the leading term. We then study the statistical properties (expectation, variance, etc.) of the duration of a successful attack.