The World Wide Web can be considered as a large distributed information system that provides access to shared data objects. As one of the most popular applications currently running on the Internet, the World Wide Web is of an exponential growth in size, which results in network congestion and server overloading. Web caching has been recognized as one of the effective schemes to alleviate the service bottleneck and reduce the network traffic, thereby minimize the user access latency. In this paper, we first describe the elements of a Web caching system and its desirable properties. Then, we survey the state-of-art techniques which have been used in Web caching systems. Finally, we discuss the research frontier in Web caching.

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A survey of web caching schemes for the Internet

This article presents a detailed workload characterization study of the 1998 World Cup Web site. Measurements from this site were collected over a three-month period. During this time the site received 1.35 billion requests, making this the largest Web workload analyzed to date. By examining this extremely busy site and through comparison with existing characterization studies, we are able to determine how Web server workloads are evolving. We find that improvements in the caching architecture of the World Wide Web are changing the workloads of Web servers, but major improvements to that architecture are still necessary. In particular, we uncover evidence that a better consistency mechanism is required for World Wide Web caches.

/pdf/a-workload-characterization-study-of-the-1998-world-cup-web-38km64wyjd.pdf

A workload characterization study of the 1998 World Cup Web site

This article presents a detailed workload characterization study of the 1998 World Cup Web site. Measurements from this site were collected over a three-month period. During this time the site received l .35 billion re uests, making this the largest throu h comparison with existing characterization studies, we are able to determinelow W eb server workloads are evolving. We find that improvements in the caching architecture of the World Wide Web are changing the workloads of Web servers, but major im rovements to that architecture are still necessary. In particular, we uncover evilence that a better consistency mechanism is required for World Wide Web caches. Web workload analyzed to date. By examining a t is extremely busy site and

/pdf/a-workload-characterization-study-of-the-7998-world-cup-web-1z2o4mwvoj.pdf

A Workload Characterization Study of the 7998 World Cup Web Site

While algorithms for cooperative proxy caching have been widely studied, little is understood about cooperative-caching performance in the large-scale World Wide Web environment. This paper uses both trace-based analysis and analytic modelling to show the potential advantages and drawbacks of inter-proxy cooperation. With our traces, we evaluate quantitatively the performance-improvement potential of cooperation between 200 small-organization proxies within a university environment, and between two large-organization proxies handling 23,000 and 60,000 clients, respectively. With our model, we extend beyond these populations to project cooperative caching behavior in regions with millions of clients. Overall, we demonstrate that cooperative caching has performance benefits only within limited population bounds. We also use our model to examine the implications of future trends in Web-access behavior and traffic.

/pdf/on-the-scale-and-performance-of-cooperative-web-proxy-3whsdgplxc.pdf

On the scale and performance of cooperative Web proxy caching

While residential broadband Internet access is popular in many parts of the world, only a few studies have examined the characteristics of such traffic. In this paper we describe observations from monitoring the network activity for more than 20,000 residential DSL customers in an urban area. To ensure privacy, all data is immediately anonymized. We augment the anonymized packet traces with information about DSL-level sessions, IP (re-)assignments, and DSL link bandwidth.Our analysis reveals a number of surprises in terms of the mental models we developed from the measurement literature. For example, we find that HTTP - not peer-to-peer - traffic dominates by a significant margin; that more often than not the home user's immediate ISP connectivity contributes more to the round-trip times the user experiences than the WAN portion of the path; and that the DSL lines are frequently not the bottleneck in bulk-transfer performance.

/pdf/on-dominant-characteristics-of-residential-broadband-350xuzyi25.pdf

On dominant characteristics of residential broadband internet traffic

Much work on the performance of Web proxy caching has focused on high-level metrics such as hit rates, but has ignored low level details such as "cookies", aborted connections, and persistent connections between clients and proxies as well as between proxies and servers. These details have a strong impact on performance, particularly in heterogeneous bandwidth environments where network speeds between clients and proxies are significantly different than speeds between proxies and servers. We evaluate through detailed simulations the latency and bandwidth effects of Web proxy caching in such environments. We drive our simulations with packet traces from two scenarios: clients connected through slow dialup modems to a commercial ISP, and clients on a fast LAN in an industrial research lab. We present three main results. First, caching persistent connections at the proxy can improve latency much more than simply caching Web data. Second, aborted connections can waste more bandwidth than that saved by caching data. Third, cookies can dramatically reduce hit rates by making many documents effectively uncacheable.

/pdf/performance-of-web-proxy-caching-in-heterogeneous-bandwidth-2urw7b3yro.pdf

G. Glass

Papers

Performance of Web proxy caching in heterogeneous bandwidth environments