Server Selection in Emerging Information Delivery Environments

点击翻译按钮获取中文摘要

Timely delivery of information from content servers to clients is now clearly one of the primary roles of ubiquitous networking. As the number of people seeking information through networks increases, scalability of information delivery services becomes an important issue. Server replication is one common technique used by service providers to accommodate the increasing information demands. Effective server replication, however, demands appropriate server selection approaches, without which the full benefits of replication will not be realized. Poor server selection often leads to an array of associated system performance implications: degraded performance as perceived by the client, possible rejection of the request due to server overload, degraded performance observed by other clients accessing the selected server, and poor performance observed by other network connections due to hot spots resulting from unbalanced load.The focus of this proposal is on the design and evaluation of server selection approaches specifically in the context of wide-area server replication. We propose a research program that provides a systematic investigation of the server selection problem starting with the current state of services and networks but mostly concerned with future networking and service environments. Continuous evolution and innovation in the capabilities of wide-area networking and the nature of information services will result in a much more complex server selection problem with a wider diversity of performance and policy concerns that affect selection. The work will consider five types of service: traditional Web and FTP services, multicast services, multimedia streamed services, multi-source services and brokered services. The researchers consider these as different service dimensions that may be present in some combination in deployed services and explore the challenges in server selection for each dimension. The researchers will also consider how new network infrastructure capabilities (ranging from support for some form of differentiated service to the more far-reaching Active Networking proposals) can be used to enhance and support the server selection function.The main contributions of the research will be:1. Development and evaluation of techniques for the use of network support to aid the server selection function.2. Characterization, mechanisms, policies and their evaluation for the multicast server selection problem.3. Techniques for streamed video server selection in current and future network environments.4. The use of the Interactive Multimedia Jukebox (IMJ) (http://imj.gatech.edu) and the researchers' previously developed multicast web server to provide proof of concept for the proposed server selection protocols for multicast and multimedia stream servers. 5. Further characterization and server selection proposals for two novel service paradigms (multiple-source and brokered services).6. A reusable experimental platform for experimenting with server selection proposals.The proposed work will go beyond server selection mechanisms in today's environment which do not need to be complex; round-robin or other simple techniques for allocating clients to servers are currently adequate. Such simple and ad-hoc techniques will not, however, work well in the richer environment that the trends above will lead to. The work considers the architecture, mechanisms and policies by which server selection may be accomplished in this future networked service environment. The researchers believe that their research will, in fact, play an enabling role, since this future's benefits cannot be realized without a workable system for server selection.