We introduce Fluidity, a framework enabling the flexible and adaptive deployment of serverless and modular applications in systems comprising cloud, edge, and mobile nodes. Based on a declarative description of application requirements, a custom placement policy, and a formal system infrastructure description, Fluidity plans and executes an initial deployment of application components in the cloud–edge–mobile continuum. Furthermore, at runtime, Fluidity monitors resource availability and the position of mobile nodes, and adapts the deployment of the application accordingly, without any manual intervention from the application owner or system administrator. These characteristics render Fluidity an enabler for serverless applications, allowing the application developers to focus on the application code itself while abstracting out the infrastructure management. Notably, Fluidity permits developers to provide their own deployment and adaptation policies as well as to switch between different policies while the application is running. We discuss the design and implementation of Fluidity in detail and provide a realistic evaluation using a lab testbed in which the mobile node is represented as a simulated drone. In addition, we evaluate the scalability of the proposed mechanisms. Our results show that the core mechanisms of Fluidity can support flexible application execution at a reasonable overhead and experimentation with different deployment policies with minimal effort.

中文翻译：

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流动性：为跨云-边缘-移动环境的无服务器和分布式应用程序提供灵活的部署和适应策略实验

我们推出 Fluidity，这是一个框架，支持在包含云、边缘和移动节点的系统中灵活、自适应地部署无服务器和模块化应用程序。基于应用程序需求的声明性描述、自定义放置策略和正式的系统基础设施描述，Fluidity 计划并执行云-边缘-移动连续体中应用程序组件的初始部署。此外，在运行时，Fluidity 监控资源可用性和移动节点的位置，并相应地调整应用程序的部署，而无需应用程序所有者或系统管理员的任何手动干预。这些特性使 Fluidity 成为无服务器应用程序的推动者，使应用程序开发人员能够专注于应用程序代码本身，同时抽象出基础设施管理。值得注意的是，Fluidity 允许开发人员提供自己的部署和适配策略，以及在应用程序运行时在不同策略之间切换。我们详细讨论了 Fluidity 的设计和实现，并使用实验室测试台提供了真实的评估，其中移动节点被表示为模拟无人机。此外，我们评估了所提出机制的可扩展性。我们的结果表明，Fluidity 的核心机制可以以合理的开销支持灵活的应用程序执行，并以最小的努力支持不同部署策略的实验。