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Reviewer: Pascal V. Calarco

The phenomenal growth of the Web and Internet networking over the last several years has created a new problem for IT professionals: how to enable Web servers to keep up with the content demands of a rapidly increasing user population. This book provides technical background relevant to this issue, and offers detailed coverage of two currently popular strategies. The book’s intended audience is, first and foremost, IT professionals and engineers. Graduate students and researchers can also use the book as a textbook for topics on Internetworking. The book is divided into four parts. The first, containing six chapters in 75 pages, provides a background in fundamental Internet infrastructure, including TCP/IP, Web application protocols, and HTTP support for caching. This part also offers some rules of thumb for benchmarking Web behavior. Part 2, “Web Caching,” contains seven chapters in 151 pages, covering the technical specifics of Web proxy caching, proxy deployment, prefetching, and strategies for caching dynamic and cookie content. Part 3 of the book, “Web Replication,” has three chapters in 71 pages. This section first provides some background for Web request distribution, then offers a particularly valuable discussion of content delivery networks, and finally offers some server selection criteria for Web replication, including metrics and algorithms to evaluate servers for this purpose. Part 4, “Further Directions,” delves more deeply into emerging areas, including content filtering, distributing Web applications, and an interesting presentation of content distribution internetworking. A 10-page glossary ends the book, along with an extensive bibliography and an index with good granularity and organization. The book offers a useful combination of technical background, academic research, and commercial application of standards and techniques. It is versatile enough to meet the demands of its diverse intended audience. Working professionals and academics alike will appreciate the rich references to the literature, including conference proceedings, papers, and Web standards documents from the late 1990s. There are a few other books available on this topic, although none provides as thorough a treatment of both caching and replication. I suggest two as compliments to this book. The first, Web caching by Duane Wessels [1], provides a more technical approach, but does not go into replication at all. It is focused more narrowly towards the system administrator. The second is the Web caching and content delivery conference proceedings [2]. These two additional works provide more practical hands-on coverage [1], and expanded information concerning academic and technical aspects [2]. Overall, the authors have provided a good mix of fundamentals, technical specifics, commercial technologies, and academic research. Their work will serve as a useful tool for the IT professional, researcher, or graduate student who is interested in findin g a single source for discussions of the state of the art of—and recent developments in—the complementary areas of Web caching and replication. Online Computing Reviews Service

Reviewer: Nguyen Ngoc Thanh

Web technologies represent one of the fastest growing fields of IT over the last decade. This is because Web technologies are applicable to almost every aspect of human life, and not merely to IT specialists. Textbooks covering these technologies are popular, and this up-to-date book should have a wide appeal. The book is well organized and well written, and covers not only caching and replication methods on the Web, but also basic Internet technologies. The book is divided into four parts, with a total of 18 chapters. Part 1 (chapters 1 to 6) includes background and prerequisite information, and provides a broad characterization of Web behavior. It contains a brief introduction to the protocols and concepts of the Web, focusing on aspects that are relevant to caching and replication. It delivers the background needed to understand the remainder of the book. Topics covered include network layers and protocols, Internet routing, the transmission control protocol, application protocols for the Web, HTTP support for caching and replication, and rules of thumb for Web behavior. Part 2 (chapters 7 to 13) presents a discussion about caching. It concentrates on issues surrounding forward proxies, and contains concrete mechanisms to implement this method. The text presents realistic expectations about proxy caching, proxy deployment, cooperative proxy caching, cache consistency, replacement policy, prefetching, and methods for caching the uncacheable. Chapter 7 considers proxies and their performance, and analyzes techniques for increasing the utility (and also the benefits) of proxies, and of caching in general. Chapter 8 discusses various alternatives for developing forward proxy caching in enterprises and Internet service providers. A mechanism to deliver a client request to the proxy, instead of the origin server specified in the request URL, is also considered. Chapter 9 discusses different methods of cooperative proxy caching, which is defined as individual proxies sharing their cached objects with each other’s clients. Chapter 10 concentrates on approaches to the cache consistency problem on the Web. Two fundamental approaches to assure cache consistency are presented: validation and invalidation. Chapter 11 presents various options for replacement policy. Chapter 12 explains commercial and research approaches to prefetching: performing work in anticipation of future needs. In chapter 13, the authors discuss how a content provider can achieve its legitimate goals in a cache-friendly way. They describe new technologies that extend cache benefits to some uncacheable content. Part 3 (chapters 14 to 16) is devoted to replication. The authors only consider transparent replication: those replication techniques that require no user involvement or even awareness of whether or not a Web site uses replication. Chapter 14 presents the basic alternatives for request redirection. Chapters 15 and 16 are devoted to the request distribution problem. They describe the basic mechanisms for request distribution on the Web, and show how these mechanisms are applied in a content delivery network environment. The authors also consider the issues of replica consistency, the performance implications of providing secure Web access via a content delivery network, and delivery of streaming content. Chapter 16 discusses the server selection problem. In part 4 (chapters 17 to 18), the authors outline new directions in caching and replication. They discuss how new services can be implemented on servers used for caching and replication. One concept presented is technology that allows caching and replication platforms operated by different enterprises to cooperate in improving overall Web performance. Chapter 17 describes several interesting services that can be implemented with the help of highly flexible and powerful proxies on the network. Chapter 18 discusses content distribution internetworking (CDI). Overall, this book contains very interesting coverage of cache and replication mechanisms on the Web. It is written in an intelligible style, and will be understandable for most readers. As the authors suggest, this book should be useful for IT professionals and to engineers at companies providing Internet services or equipment. A second group of potential readers is researchers and graduate students in fields such as information systems and networking. Finally, the book could be of interest to anyone who would like to use the Internet in a more active way. Online Computing Reviews Service