CISE Research Instrumentation: Semantics-based Prefetching for Mobile Computing

Kaiser, Gail E. Duchamp, Daniel J.哥伦比亚大学基于语义的移动计算预取该提案研究了协作工作流环境，并且先前构建了一个假设传统高速网络的基础设施。凯泽教授正在开发新的算法和技术来支持移动主机。该研究解决了基于用户下一步可能做什么的语义信息的预取问题，这些信息来自定制特定环境实例的工作流定义，以允许协作企业中的参与者进行低带宽和暂时分离的操作。Duchamp教授正在开发操作系统支持，以智能地从文件系统中预取文件或从对象库中预取对象。目标是通过两种类型的预取来提高性能并在断开网络连接之前自动加载缓存：第一种由文件系统执行，对应用程序透明；文件系统“学习”文件访问模式，并在模式重复出现时使用这些模式预取。第二种类型的预取是面向应用程序的；了解未来数据访问的应用程序可以使用一个特殊的接口来指示操作系统预取什么。Kaiser教授的工作流系统是这类预取的主要示例应用程序。协作工作和操作系统方向都需要移动笔记本计算机来进行原型支持的开发、测试和度量。

CDA 95-29304 Kaiser, Gail E. Duchamp, Daniel J. Columbia University Semantics-based Prefetching for Mobile Computing This proposal investigates collaborative workflow environments, and previously constructed an infrastructure that assumes conventional high-speed networking. Professor Kaiser is developing new algorithms and techniques to support mobile hosts. The research addresses prefetching based on semantic information on what the user is likely to do next drawn from the workflow definition tailoring the specific environment instance, to permit low-bandwidth and temporarily detached operation by participants in collaborative enterprises. Professor Duchamp is developing operating system support for intelligently prefetching files from a file system or objects from an objectbase. The goal is to improve performance and automate cache loading prior to disconnecting from the network, via two types of prefetching: The first is performed by the file system, transparent to applications; the file system ``learns'' file access patterns and uses these patterns to prefetch if/when the patterns recur. The second type of prefetching is application-directed; applications with knowledge of their future data accesses can use a special interface to instruct the operating system what to prefetch. Professor Kaiser's workflow system is the major example application for this type of prefetching. Both the collaborative work and operating systems directions require mobile notebook computers for development, testing, and measurement of the prototype support.