Consideration of Service Time in Placing Clients of Web-Based Services

Web-based services involving dynamic computation of the content are increasingly used on the Web. This computation may not only involve processing, but often involves access to other back-end services typically for database access. These multi-tiered Web-based services have different characteristics than traditional Web content and new models need to be considered not only how to manage them, but also how the DNS mechanism should map clients to the appropriate front-end server. In this work we study the potential of considering back-end service times in the decision of mapping clients to servers. We do so by gathering data from deployed platforms in the Internet today from client locations both scattered around the globe and around the United States. We use these data for the simulation of straightforward policies that account for back-end service time. Our results show that in the best case our simple policies have better performance than using current DNS decisions, while in the worst case they provide comparable performance for a range of performance metrics.