Serverless Function-as-a-Service (FaaS) platforms provide applications with resources that are highly elastic, quick to instantiate, accounted at fine granularity, and without the need for explicit runtime resource orchestration. This combination of the core properties underpins the success and popularity of the serverless FaaS paradigm. However, these benefits are not available to most cloud applications because they are designed for networked virtual machines/containers environments. Since such cloud applications cannot take advantage of the highly elastic resources of serverless and require run-time orchestration systems to operate, they suffer from lower resource utilization, additional management complexity, and costs relative to their FaaS serverless counterparts. We propose Imaginary Machines, a new serverless model for cloud applications. This model (1.) exposes the highly elastic resources of serverless platforms as the traditional network-of-hosts model that cloud applications expect, and (2.) it eliminates the need for explicit run-time orchestration by transparently managing application resources based on signals generated during cloud application executions. With the Imaginary Machines model, unmodified cloud applications become serverless applications. While still based on the network-of-host model, they benefit from the highly elastic resources and do not require runtime orchestration, just like their specialized serverless FaaS counterparts, promising increased resource utilization while reducing management costs.

翻译：无服务器函数即服务（FaaS）平台为应用程序提供高度弹性、快速实例化、细粒度计费且无需显式运行时资源编排的资源。这些核心特性的结合支撑了无服务器FaaS范式的成功与普及。然而，大多数云应用无法获得这些优势，因为它们是为网络化虚拟机/容器环境设计的。由于此类云应用无法利用无服务器平台的高度弹性资源，且需要运行时编排系统才能运行，相较于专门的FaaS无服务器应用，它们存在资源利用率较低、管理复杂度增加和成本更高的问题。本文提出"虚拟机器"——一种面向云应用的新型无服务器模型。该模型（1）将无服务器平台的高度弹性资源以云应用所期望的传统主机网络模型形式呈现；（2）通过基于云应用执行过程中生成的信号透明管理应用资源，消除了对显式运行时编排的需求。借助虚拟机器模型，未经修改的云应用即可转变为无服务器应用。虽然仍基于主机网络模型，它们却能获得高度弹性资源且无需运行时编排，正如专门的无服务器FaaS应用一样，有望在降低管理成本的同时提升资源利用率。