Collaborative Research (NSF-CNPq): Application Level Adaptation and Control for Retrieval and Delivery of Continuous Media over the Internet

未来的网络化多媒体信息系统将承载广泛的应用，包括数字图书馆、视频、音频和图像服务、远程学习和协作、网络虚拟环境和娱乐。导致端到端系统设计困难的多媒体应用的主要特征是它们具有非常大的带宽和存储需求，具有非常不同的性能和可靠性要求，并且经常伴随着实时约束。伴随着这些特点，高度的相互可靠性要求，往往伴随着实时约束。伴随着这些特点，各种多媒体应用的高度交互特性导致了相当不可预测的工作量，使得网络多媒体信息系统的设计和评估成为一个特别具有挑战性的问题。在该方案中，我们概述了这一问题的三个方面的研究：(1)设计和评估CM服务器的服务器资源分配算法，以便高效地根据应用程序的服务质量检索信息；(2)开发用于评估新服务器设计的性能评估技术。(3)这个项目的参与者带来了来自数据库、远程教育、多媒体、网络和绩效评估等广泛领域的专业知识，以解决这些领域的问题。这项提案的另一个重要特点是，与会者拥有最先进的多媒体系统的四个原型：加州大学洛杉矶分校开发的虚拟世界数据服务器(VWDS)：巴西作为巴西机构合作研究项目的一部分开发的视频点播服务器的原型；以及马萨诸塞州大学开发的多媒体异步联网个性化课程(MANIC)和互联网多媒体代理(IMP)。这些应用程序将被用来推动开发新的算法，以便在广域网上发送数据后检索信息和保持所需的服务质量。它们还将构成许多实验和分析研究的基础，这些研究将被执行以评估这些新算法。为了帮助进行这项评估，我们团队还开发了三个性能评估和建模工具：与加州大学洛杉矶分校联合在巴西开发的用于构建性能和可靠性模型的最先进工具(Tangram-II)；符号模型检查工具(VERUS)：以及促进UMD正在开发的多媒体存储层次结构(Viper-HISS)设计的设计、开发和后续性能评估的工具。因此，我们实验室的环境以及它们之间的远距离将为这类评估提供独特的试验台，因为我们的应用程序可用的连接性截然不同，从千兆位低利用率链路到洲际拥塞链路。拟议的研究是下一代信息服务器和将在其上运行的联网应用程序的设计和性能评估的重要一步。通过我们的研究，我们希望更好地了解存储服务器资源管理策略、通道分配策略和网络适配策略如何相互作用，以满足CM应用程序所需的服务质量，尽管存在相当不可预测的网络延迟。

Future networked multimedia information systems will carry a wide variety of applications including digital libraries, video, audio and image services, distance learning and collaboration, networked virtual environments, and entertainment. The main characteristics of multimedia applications that lead to difficulties in end-to-end systems design are that they have very large bandwidth and storage requirements, with vastly different performance and reliability requirements, often coupled with real-time constraints. Along with these characteristics, the highly interreliability requirements, often coupled with real-time constraints. Along with these characteristics, the highly interactive nature of a variety of multimedia applications, resulting in fairly unpredictable workloads, makes the design and evaluation of networked multimedia information systems an exceptionally challenging problem. In this proposal, we outline research on three aspects of this problem: (1) the design and evaluation of server resource allocation algorithms for CM servers in order to retrieve information efficiently and according to the QoS demanded by the application; (2) the development of performance evaluation techniques for evaluating new server designs. (3) the participants of this project bring expertise from a wide variety of areas: databases, distance learning, multi-media, networking, and performance evaluation to bear on problems in these areas. Another important feature of this proposal is that the participants have available four prototypes of state of the art multimedia systems: the Virtual World Data Server (VWDS) developed at UCLA: the prototype of a Video-on-Demand server developed in Brazil as part cooperative research project among Brazilian institutions; and the Multimedia Asynchronous Networked Individualized Courseware (MANIC) and the Internet Multimedia Proxy (IMP) both developed at UMass. These applications will be used to motivate the development of new algorithms for retrieving information and for maintaining the desired quality of service after sending the data over a wide area network. They will also form the basis of the many experimental and analytical studies that will be performed to evaluate these new algorithms. To aid in this evaluation, our group also developed three performance evaluation and modeling tools: a state-of-the-art tool for constructing performance and reliability models (Tangram-II) developed in Brazil jointly with UCLA; a symbolic model checking tool (VERUS): and a tool which facilitates design, development, and subsequent performance evaluation of designs of multimedia storage hierarchies (ViPEr-HiSS) under development at UMD. Thus, the environment of our labs as well the long distance among them will provide a unique testbed for this type of an evaluation due to the drastically different connectivities available to our applications, from gigabit low utilized links to intercontinental congested links. The proposed research represents a fundamentally important step in the design and performance evaluation of next generation information servers and the networked applications that will operate on top of them. As a result of our research we expect to have a better understanding of how storage server resource management policies, channel allocation policies, and network adaptation policies interact to satisfy the required QoS of CM applications, despite the fairly unpredictable network delays.