Application-level document caching in the Internet

Abstract

With the increasing demand for document transfer services such as the World Wide Web comes a need for better resource management to reduce the latency of documents in these systems. To address this need, we analyze the potential for document c a c hing at the application level in document transfer services. We h a ve collected traces of actual executions of Mosaic, re ecting over half a million user requests for WWW documents. Using those traces, we study the tradeo s between caching at three levels in the system, and the potential for use of application-level information in the caching system. Our traces show that while a high hit rate in terms of URLs is achievable, a much l o wer hit rate is possible in terms of bytes, because most pro tably-cached documents are small. We consider the performance of caching when applied at the level of individual user sessions, at the level of individual hosts, and at the level of a collection of hosts on a single LAN. We show that the performance gain achievable by c a c hing at the session level (which is straightforward to implement) is nearly all of that achievable at the LAN level (where caching is more di cult to implement). However, when resource requirements are considered, LAN level caching becomes much more desirable, since it can achieve a g i v en level of caching performance using a much smaller amount o f c a c he space. Finally, w e consider the use of organizational boundary information as an example of the potential for use of application-level information in caching. Our results suggest that distinguishing between documents produced locally and those produced remotely can provide useful leverage in designing caching policies, because of di erences in the potential for sharing these two document t ypes among multiple users.

Thin-client Web access patterns: Measurements from a cache-busting proxy

“…Results for both the BPS sample and the entire client population are shown in Figure 10; the estimates of actual WebTV browser hit rates from Table 2 are included for comparison. Our results are comparable to the success function presented in Figure 5 of Bestavros et al, which assumes LFU replacement [12]. Aggregate browser cache success functions are needed in order to make informed tradeoffs between browser functionality and cache hit rates in thin-client systems such as WebTV.…”

Web servers under overload: How scheduling can help

“…Most of this work focuses on improving performance by reducing the load on the overloaded devices in the system. This is typically done in one of four ways: increasing the capacity of the system for example by using server farms or multiprocessor machines [20,22]; using caches either on the client or on the server side [26,15,13]; designing more efficient software both at the OS level [34,7,23,29] and the application level [37], and admission control [17,44]. Other means of avoiding overload are content adaptation [1] and offloading work to the client [3].…”

Theories and models for Internet quality of service

“…One method for dealing with delays due to congested end-to-end paths between servers and clients is to cache web objects close to the client [142], [143]. This is the primary rationale for the establishment of content distribution networks (CDNs) such as the Akamai network.…”