Web Caching and Its Applications

By S.V. Nagaraj

262 pages

US$105

Springer, 2004

ISBN: 1-4020-8049-2

Web caching technology improves client download times and reduces network traffic by caching frequently accessed copies of Web objects close to the clients. The primary research issues in Web caching are where to cache copies of objects (cache placement), how to keep the cached copies consistent (cache consistency), and how to redirect clients to the optimal cache server (client redirection).

Web caching systems' design space is huge, and building a good caching system involves several issues. Over the past decade, researchers have carried out a tremendous amount of work in addressing these issues. In Web Caching and Its Applications, S.V. Nagaraj aims to provide a bird's eye view of this research. He has exhaustively surveyed the literature and summarized the results of several research publications.

Nagaraj organizes the literature into six parts. The first part covers cache placement issues: cache servers' organization, cache placement, and dynamic document caching. The second part surveys results on cache replacement, routing cache requests, and cache consistency. The third part surveys studies on Web traffic analysis and forecasting access patterns. The fourth part presents works on prefetching and replication techniques, and the fifth surveys solutions to fault tolerance and load-balancing problems. Finally, the book discusses measuring Web cache performance.

The first three parts are reasonably well done and are the book's forte. Nagaraj has done a commendable job of covering research addressing cache server organization and cache replacement.

However, the material he presents in the final three parts, addressing issues such as fault tolerance, load balancing, and replication, are fairly superficial. The book doesn't clearly distinguish between caching and replication, which introduces some redundancy. Moreover, Nagaraj barely discusses caching techniques that address flash crowds (huge surges in client load) or handle distributed denial-of-service attacks. Also, he doesn't provide any case studies that detail the design of popular caching systems such as Squid (http://www.squid-cache.org) or content-delivery networks such as Akamai (http://www.akamai.com). This, unfortunately, makes the book less attractive for Web proxy administrators or system designers.

Another drawback is the book's style. Aiming to be exhaustive, each chapter summarizes all the research publications that address the problem it discusses. For example, the chapter concerning dynamic document caching presents the abstracts of all research publications that address this problem. A clearer approach would have been to present the problem and the key ideas behind the solutions that address it. This would have significantly improved the book's readability.

Web Caching and Its Applications can serve as a reference tool for researchers and for graduate students working on Web systems. However, its approach isn't suitable for Web administrators or students who are new to the field. If you're a student trying to understand Web caching issues, I recommend skipping the "Further Reading" section in each chapter; this will help narrow the focus on the problem each chapter presents.

Swaminathan Sivasubramanian is a PhD student at Vrije Universiteit, Amsterdam. Contact him at swami@cs.vu.nl.