CSR: Small: Elastic and Robust Cloud Programming

云计算的出现无疑是过去十年来信息技术领域的重大范式转变之一，并对经济产生了重大影响。事实上，根据需要租用计算资源的能力(而不是获取和管理为极少发生的高峰工作负载配置的基础设施)支持许多不同类型和规模的企业。然而，尽管云基础设施允许非常动态地分配和释放计算资源，但开发利用这一潜力在运行时根据其工作负荷(例如，客户端连接的数量)和性能目标自动调整其资源使用的软件对于软件工程师来说是一项艰巨的任务。因此，该项目的目标是以编程模型和运行时环境的形式为程序员提供支持，以开发这样的弹性应用程序。然而，设计这样的通用编程模型是非常具有挑战性的，因为它必须兼顾简单性(对于程序员)、可伸缩性(通过促进并行性和分布)和健壮性(通过处理部分故障)。不幸的是，这些属性可能会发生冲突。该项目通过以下贡献应对挑战。(1)编程模型和语言：提出了一种新的面向对象编程模型变体原子事件和所有权网络(AEON)。永旺将简化的对象模型与一种新型的多重所有权相结合来推理应用程序状态的单元，以简化这些单元之间的交互，并结合了用于原子客户端-服务器交互的新颖的事件概念。(2)分布式运行环境：为永旺实现了一个高度可扩展和分散的运行环境，支持动态添加和删除计算单元，并支持它们之间的关系重组，而不会阻碍一致性或相反地阻碍进度。还提出了有效(重新)划分AEON应用程序的启发式算法。(3)资源管理和容错：利用资源管理框架来促进应用单元和底层资源之间的映射；对其进行扩充，以提供实现容错的可靠资源的概念。(4)评估：开发的支持在各种应用程序和不同的云基础设施上进行评估。所有的开发都是基于开源软件。

The emergence of cloud computing is undoubtedly one of the major paradigm shifts of the last decade in information technology, and one with substantial economic impact. Indeed, the ability to rent computing resources on a need basis (as opposed to acquiring and managing infrastructure provisioned for peak work loads that may occur only rarely) supports many businesses of different kinds and sizes. However, while cloud infrastructures allow computing resources to be allocated and released very dynamically, developing software that leverages this potential to automatically adjust its usage of resources to its workload (e.g., the number of client connections) and performance goals at runtime is a hard task for software engineers. The goal of this project is thus to provide programmers support in the form of a programming model and runtime environment for developing such elastic applications. Devising such a generic programming model is however very challenging as it must reconcile simplicity (for programmers) with scalability (by facilitating parallelism and distribution) and robustness (by handling partial failures). Unfortunately, these properties may conflict. This project addresses the challenges through the following contributions. (1) Programming model and language: a novel object-oriented programming model variant called Atomic Events and Ownership Network (AEON) is proposed. AEON combines a simplified object model to reason about units of application state with a novel type of multiple ownership to streamline interaction between these units, and a novel notion of events for atomic client-server interaction. (2) Distributed runtime environment: a highly scalable and decentralized runtime environment for AEON is implemented, with support for dynamically adding and removing computational units, as well as for supporting the restructuring of their relationships without hampering consistency or conversely stalling progress. Heuristics to efficiently (re-)partition AEON applications are also proposed. (3) Resource management and fault tolerance: a resource management framework is leveraged for facilitating the mapping between application units and underlying resources; it is augmented to provide a notion of dependable resources achieving fault tolerance. (4) Evaluation: the developed support is evaluated on a wide variety of applications and across different cloud infrastructures. All developments are based on open-source software.