This work focuses on characterizing information about Web resources and server responses that is relevant to Web caching. The approach is to study a set of URLs at a variety of sites and gather statistics about the rate and nature of changes compared with the resource type. In addition, we gather response header information reported by the servers with each retrieved resource. Results from the work indicate that there is potential to reuse more cached resources than is currently being realized due to inaccurate and nonexistent cache directives. In terms of implications for caching, the relationships between resources used to compose a page must be considered. Embedded images are often reused, even in pages that change frequently. This result both points to the need to cache such images and to discard them when they are no longer included as part of any page. Finally, while the results show that HTML resources frequently change, these changes can be in a predictable and localized manne...
Craig E. Wills, Mikhail Mikhailov