CSR: Small: Elastic and Robust Cloud Programming

云计算的出现无疑是过去十年信息技术的主要范式转变之一，也是具有重大经济影响的转变之一。事实上，根据需要租用计算资源的能力（与获取和管理为可能很少发生的峰值工作负载提供的基础设施相反）支持许多不同类型和规模的企业。然而，虽然云基础设施允许非常动态地分配和释放计算资源，但是开发利用这种潜力来自动调整其资源使用以适应其工作负载的软件（例如，客户端连接的数量）和运行时的性能目标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开发此类弹性应用程序提供程序员支持。然而，设计这样一个通用的编程模型是非常具有挑战性的，因为它必须协调简单性（程序员）与可扩展性（通过促进并行性和分布）和鲁棒性（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的编程模型变体，称为原子事件和所有权网络（AEON）。AEON结合了简化的对象模型来推理应用程序状态单元，并结合了新型的多所有权来简化这些单元之间的交互，以及用于原子客户端-服务器交互的事件的新概念。(2)分布式运行时环境：实现了AEON的高度可扩展和分散的运行时环境，支持动态添加和移除计算单元，以及支持它们的关系的重构，而不妨碍一致性或相反地停止进展。启发式有效地（重新）分区AEON应用程序也提出了。(3)资源管理和容错：利用资源管理框架来促进应用程序单元和底层资源之间的映射;它被增强以提供实现容错的可靠资源的概念。(4)评估：在各种应用程序和不同的云基础设施上对开发的支持进行评估。所有开发都基于开源软件。

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.