System Support for Scalable Distributed Services

点击翻译按钮获取中文摘要

As internetworked computing becomes pervasive, common services will be accessed by a large number of widely distributed clients. Thus, scalable implementations of such services must deal with (1) large number of clients, and (2) high latencies that will be common among widely distributed nodes. One approach for reducing server load and communication costs is to create multiple instances of a service close to client groups that frequently access it. Also, when possible, resource rich clients can cache service state to avoid communication latency for common accesses. Service state replication and caching both lead to multiple copies of the service state and lead to the problem of consistency maintenance across copies when service state can be updated (e.g., to support interactions across clients). The focus of this project is on the characterizations of consistency levels that are appropriate in large scale systems with diverse sets of applications. In addition, scalable protocols will be developed to provide both read and write access to service state without requiring communication with all nodes that may have copies of the service state. A distributed object based middleware will be implemented to support scalable service and it will employ object caching and replication to enhance service access performance and scalability. This middleware will be used in the development and evaluation of services targeted to the home that are reached via a variety of communication media such as POTS and cable networks.