Scalability and Composability in Distributed Ledgers

区块链是分布式计算的下一个前沿，它从白色论文迅速上升到顶级出版物和数百万美元的初创公司，引起了学术界和从业者的关注。 围绕区块链和更广泛的分布式账本的大部分讨论都围绕着两个基本问题：（i）它们是否会扩展以满足当前和新兴的需求，以及（ii）我们能否相信它们的正确性？ 这些问题将通过一个多方面的研究计划，将从事实证和理论方法来回答。 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伸缩性。 可扩展性已被认为是分布式账本的一个主要弱点，这导致人们寻求通过仔细组合其输出来组成多个独立服务的设计，以获得对交易的全局排序。这个目标将侧重于了解如何正确地实现这种组合，以及它们如何影响吞吐量和延迟之间的固有权衡。 目标2：在没有失败的情况下简化执行。 区块链协议很复杂，因为它们必须处理并发和故障，并且可以在没有故障的情况下大大简化。该目标将研究性能优化，以无故障操作加速区块链，同时即使在不利条件下也能保持正确性。 将开发模块化设计，可以与各种现有的区块链协议相结合。 目标3：了解一致性-延迟权衡。 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。 这个目标将了解在给定的概率阈值内检测双重花费需要多少延迟，这可以被视为与NoSQL存储系统中遇到的一致性延迟权衡。 目标4：基础和应用。 该目标将研究分布式账本的理论基础，并对其性能权衡进行更深入的实证理解。研究成果可能包括严格的正确性属性的定义，理论复杂性界限的证明，和经验的性能评估。 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最前沿。 参与NSERC资助的活动的学员将在体验式学习环境中蓬勃发展，他们将亲自使用最先进的云基础设施并与行业合作伙伴互动，同时开发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.