Dynamically Selecting Optimal Distribution Strategies for Web Documents

To improve the scalability of the Web it is common practice to apply caching and replication techniques. Numerous strategies for placing and maintaining multiple copies of Web documents at several sites have been proposed. These approaches essentially apply a global strategy by which a single family of protocols is used to choose replication sites and keep copies mutually consistent. We propose a more flexible approach by allowing each distributed document to have its own associated strategy. We propose a method for assigning an optimal strategy to each document separately and prove that it generates a family of optimal results. Using trace-based simulations, we show that optimal assignments clearly outperform any global strategy. We have designed an architecture for supporting documents that can dynamically select their optimal strategy, and evaluate its feasibility using a prototype implementation running in an emulated Internet environment.