In Cache ? Object Expiry Time Reached ? Object Refresh Interval Time Reached ? from Cache

The continued increase in demand for information services on the Internet is showing signs of strain. While the Internet is a highly distributed system, individual data objects most often have only a single source. Host computers and network links can easily become overloaded when a large number of users access very popular data. Proxy-caching is currently a popular way to reduce network bandwidth, server load and to improve response time to the user. The original caching proxy, from CERN, is probably still the most widely used. This paper describes software developed by the author that investigates some alternative techniques for caching WorldWide Web objects. This software complements traditional proxy-caching by allowing servers to explicitly grant or deny permission to cache an object, and with support for server-initiated callback in-validation of changed objects.