Scalability and Composability in Distributed Ledgers

区块链是分布式计算的下一个前沿领域，它从白皮书迅速上升到顶级出版物和数百万美元的初创公司，引起了学术界和实践者的注意。围绕区块链以及更普遍的分布式账本的大部分讨论都围绕着两个基本问题：(i)它们是否能够扩展以满足当前和新兴的需求，以及（ii）我们是否可以相信它们的正确性？这些问题将通过一个多方面的研究计划来回答，该计划将采用实证和理论方法。nserc资助的研究活动将解决以下短期目标：目标1：通过可组合性实现可扩展性。可扩展性被认为是分布式账本的一个主要弱点，它导致人们寻找通过仔细组合其输出来组合多个独立服务的设计，以获得对事务的全局排序。本目标将侧重于理解如何正确实现这样的组合，以及它们如何影响吞吐量和延迟之间的内在权衡。目标2：在没有失败的情况下简化执行。区块链协议很复杂，因为它们必须同时处理并发性和故障，并且可以在没有故障的情况下大大简化。本目标将研究在无故障运行中加速区块链的性能优化，同时即使在不利条件下也能保持正确性。模块化设计将被开发，可以与各种现有的区块链协议相结合。目标3：理解一致性和延迟的权衡。区块链协议必须验证交易，以防止双重支出并确保数据一致性。这个目标将帮助理解在给定的概率阈值内检测双重花费需要多少延迟，这可以看作是一致性-延迟的权衡，类似于在NoSQL存储系统中遇到的问题。目标4：基础和应用。本目标将检查分布式账本的理论基础，并获得对其性能权衡的更深入的经验理解。研究成果可能包括正确性属性的严格定义，理论复杂性界限的证明和经验性能评估。拟议的研究计划将通过生成具体的软件原型以及描述协议、正确性证明和性能比较的科学出版物，将加拿大提升到区块链技术研究的前沿。参与nserc资助活动的学员将在体验式学习环境中蓬勃发展，在这里他们将亲身体验最先进的云基础设施，并与行业合作伙伴互动，同时培养对加拿大日益数据驱动的经济至关重要的技术技能。

Blockchain is the next frontier of distributed computing, and its rapid ascent from white papers to top-tier publications and multi-million dollar startups has caught the attention of both academics and practitioners. Much of the discussion surrounding blockchains, and more generally distributed ledgers, revolves around two fundamental questions: (i) will they scale to meet current and emerging demands, and (ii) can we trust their correctness? These questions will be answered through a multi-faceted research program that will engage both empirical and theoretical methodologies. NSERC-funded research activities will address the following short-term objectives: Objective 1: Scalability through composability. Scalability has been recognized as a major weakness of distributed ledgers, leading to a search for designs that compose multiple independent services by combining their outputs carefully to obtain a global ordering over transactions. This objective will focus on developing an understanding of how such compositions can be achieved correctly, and how they affect the inherent trade-off between throughput and latency. Objective 2: Streamlining execution in the absence of failures. Blockchain protocols are complex as they must handle both concurrency and failures, and can be simplified substantially in absence of failures. This objective will investigate performance optimizations that speed up blockchains in failure-free operation while maintaining correctness even under adverse conditions. Modular designs will be developed that can be combined with a variety of existing blockchain protocols. Objective 3: Understanding consistency-latency trade-offs. A blockchain protocol must validate transactions to prevent double-spending and ensure data consistency. This objective will develop an understanding of how much latency is required to detect double-spending within a given probability threshold, which can be viewed as a consistency-latency trade-off similar to those encountered in NoSQL storage systems. Objective 4: Foundations and applications. This objective will examine the theoretical foundations of distributed ledgers, and gain a deeper empirical understanding of their performance trade-offs. Research outcomes may include rigorous definitions of correctness properties, proofs of theoretical complexity bounds, and empirical performance evaluations. The proposed research program will elevate Canada to the forefront of research in blockchain technology by generating concrete software prototypes as well as scientific publications describing protocols, proofs of correctness, and performance comparisons. Trainees engaged in NSERC-funded activities will flourish in an experiential learning environment where they will work hands-on with state-of-the-art cloud infrastructure and interact with industry partners, while developing technical skills vital to Canada's increasingly data-driven economy.