Web Caching and Replication

Chapter 10. Cache Consistency

As we have seen, caching creates numerous copies of Web objects scattered throughout the Internet. If an object is updated at the origin server, copies of that object cached elsewhere become stale. Without special mechanisms to enforce the freshness of cached data, a proxy may continue using a stale cached copy of the object. The problem of ensuring that proxies and browsers use only fresh cached content is called the cache consistency problem. While the cache consistency problem arises in numerous computer environments, it is especially difficult in the Web context, due to its scale and to loose coupling between origin servers on one side and proxies and browsers on the other. This chapter concentrates on approaches ...