Designing and Implementing Adaptive Distributed Systems

自适应计算系统是一种根据环境的变化来发展其行为的系统。对于构建在分布式体系结构上的适应性系统（其中多台机器通过网络连接），此类更改的范围可以从站点故障到更新的应用程序需求。当发生更改时所采取的演进操作也可能不同，从动态地重新配置系统软件以在更改的条件下保持相同的服务保证，到与应用程序协商新的服务保证。该项目的目标是开发设计和实现自适应分布式计算系统的基本新技术。具体的重点是提供一个分布支持层，这是一个软件层，实现了关于应用程序的分布式状态的强大执行保证，可以适应变化。本研究集中于两方面的研究：(1)为这种类型的系统开发一个概念模型；(2)基于称为微协议的细粒度代码模块实现自适应分布式系统的新方法。该框架正在被扩展以支持软件的动态演进，包括重新配置、动态代码链接和运行时代码生成。* * *

An adaptive computing system is one that evolves its behavior based on changes in the environment. For an adaptable system built on a distributed architecture where multiple machines are connected by a nework, such changes can range from site failures to updated application requirements. The evolutionary action taken when a change occurs can vary as well, ranging from dynamically reconfiguring the system software to maintain the same service guarantees under changed conditions, to negotiating new service guarantees with the application. The goal of this project is to develop fundamental new techniques for designing and implementing adaptive distributed computing systems. The specific focus is on providing a distribution support layer, a software layer implementing strong execution guarantees regarding the distributed state of the application, that can adapt to changes. The research concentrates on two lines of investigation: (1) the development of a conceptual model for systems of this type and (2) a new approach to implementing adaptive distributed systems based on fine-grain code modules called micro-protocols. The framework is being extended to support dynamic evolution of software, including reconfiguration, dynamic code linking, and runtime code generation. ***