Web预取技术综述

A Survey of Web Prefetching

Web预取是减少用户访问延时、提高网络服务质量的关键技术之一,近年来已成为国内外的研究热点.通过利用WWW访问的空间局部性,Web预取使缓存机制从时间局部性向空间局部性扩展.归纳了Web预取技术的分类,概括和比较了不同类别的优势和局限性,给出了预取模型的基本框架及每部分的主要功能,并对各种评价标准进行了详细介绍.同时,深入分析和探讨了现有的几种典型预取算法,系统地比较了这些算法的优缺点.最后从在线性、协作预取、动态流行度、划分用户会话和基于语义与基于路径相结合等方面指出了Web预取技术的研究方向.

Web prefetching is one of the key techniques to reduce the user access latency and improve the quality of service of the network. It is a hot research topic that has gained increasing attention all over the world in recent years. The main advantage of employing prefetehing is to complement the existing Web cache mechanisms and overcome the inherent limitation of Web caching in capitalizing on the spatial locality of Web accesses. In this paper, the classification of Web prefetching techniques is summarized from the perspective of the location of Web prefetching. The limitation and superiority of different types of prefetching are compared and surveyed. Based on a lot of research results in the open literature, a basic prefetching model is given and the function of its each important component is described. The evaluation criteria of Web prefetching are discussed and analyzed in detail. As the key problem of the Web prefetehing model, Web prefetching algorithms are roughly classified into several categories, which are based on dependency graph, Markov model, data mining, cost function, and semantic preferences. The advantages and disadvantages of these algorithms are systematically analyzed and compared. Finally, several major issues and research directions of Web prefetching for further exploration are also pointed out.