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The Pros and Cons of Web Caching--and How to do it Right

July 9, 2001

Sebastopol, CA--There are many arguments for the practice of web caching, and it seems, almost as many against. In his just-released book, Web Caching (O'Reilly, US $39.95), Duane Wessels explains the theory and benefits of web caching. He also explores the politics that surround web caching, touching on the fears of security, privacy, and copyright infringement that accompany the topic. Rather than dismissing these fears outright, Wessels examines the thinking behind them, and provides insightful solutions in a way that administrators will thoroughly understand the issues and the choices they have for dealing with them. As Wessels shows, web caching, when properly done, can be a boon to network administrators and users alike.

The practice of web caching has exploded within recent years. It is estimated that between 40,000 and 60,000 organizations are operating web caches; among these two-thirds are using open source caching software. Types of web caches range from familiar browser caches to caching proxies that serve many different users at once, all the way to clusters of caches that talk to each other.

"Web caching is important for a number of reasons," Wessels explains. "First of all, it saves organizations time and money. People that use web caches spend less time waiting for pages to download. Web caching improves the utilization of network connections so organizations that pay for bandwidth get more for their money. Many caching proxies also have features that protect users privacy and improve network security."

Web Caching provides network administrators with all the information they will need to design, implement, and tune a web cache system. The book lays out the basics of cache design, including protocols and operation, and describes implementation issues and performance monitoring. Also discussed in full detail is Squid, one of the most popular open source caching programs.

Topics covered in Web Caching include:

  • Designing an effective cache solution
  • Configuring web browsers to use a cache
  • Setting up a collection of caches that can talk to each other
  • Configuring an interception cache or proxy
  • Monitoring and fine-tuning the performance of a cache
  • Configuring web servers to cooperate with web caches
  • Benchmarking cache products

"Web caching is as important now as it ever has been," Wessels says. "There has been a lot of buzz recently about Content Distribution Networks. These CDNs, however, only improve the performance of content providers who can afford the high subscription fees. A web cache located on an organization's network improves the performance of all sites visited by users. Furthermore, CDNs do not offer any of the privacy and security features that caching proxies do."

According to Wessels, Web Caching is relevant to administrators who are responsible for the day-to-day operation of one or more web caches, such as administrators for ISPs, corporations, or educational institutions. Content providers and developers should also be knowledgeable about the workings of web caches. For example, anyone developing an application that uses HTTP will need to understand how web caching works, as many of their users are behind firewalls and web caches. As Wessels explains, "A significant amount of HTTP traffic is automatically intercepted and sent to web caches. Failure to take caching issues into consideration may adversely affect the operation of your application."

Online Resources:

Web Caching
By Duane Wessels
July 2001
ISBN 1-59692-536-X, 300 pages, $39.95 (US)

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