Designing Communication Support for Mobile Hosts in Distributed Systems

蜂窝通信、无线局域网和卫星服务技术的迅速发展，将使用户随时随地获取信息成为可能。在这种环境中，用户将是移动的，使用低性能计算机，并通过窄带宽链路与网络通信。这样的环境给通信机制的设计带来了新的挑战，因为带宽、能量、成本和主机移动性导致的计算资源可用性等限制。因此，通信协议的设计应该适应移动性带来的环境变化。研究项目将使用以下方法设计和构建对移动通信应用程序的支持，这些应用程序明确考虑到带宽限制、能源限制和移动性：(1)客户端和服务器之间的通信将通过中介进行。间接交互允许优化和开发无线链路和移动主机的专用协议，而不必更改在固定主机上运行的任何协议。(2)设计环境感知通信原语，该原语将可以访问当前环境状态，并在发生任何更改时得到通知。因此，要使用的通信类型可以根据当时的情况进行调整。

The rapidly expanding technology of cellular communications, wireless LAN, and satellite services will make it possible for users to access information anywhere and at anytime. In this environment, users will be mobile, use low powered computers, and communicate with the network over narrow bandwidth links. Such an environment introduces new challenges in the design of communication mechanisms due to constraints such as bandwidth, energy, cost, and the availability of computing resources due to host mobility. Hence, communication protocols should be designed for adaptability to changing environments brought by mobility. The research project will design and build support for mobile communications applications that explicitly take into account bandwidth limitations, energy limitations, and mobility using the following approaches: (1) The communication between the client and the server will be via an intermediary. Indirect interaction allows for optimization and development of specialized protocols for the wireless link and mobile host without having to change any protocol that is running on the fixed hosts. (2) Design environment aware communication primitives that will have access to the current environment state and also be notified about any changes. Thus, the type of communication to use can be tailored to the prevailing conditions.