A protocol for improved user perceived QoS in Web transactional applications

Quality-of-service (QoS) provisioning in the Internet has been a topic of active research in the last few years. However, due to both financial and technical reasons, the proposed solutions are not commonly employed in practice. As a consequence, the Internet architecture is still mainly oriented to a best effort delivery model, which does not provide any guarantee neither on the message delivery latency, nor on the probability that a service residing at some host becomes temporarily unreachable due to network congestion. We address this issue by presenting an innovative, application level protocol tailored for Web transactional applications, which attempts to reduce the impact of network congestion on the latency experienced by the end-users. The intuition underlying our proposal is to exploit the intrinsic potential of parallelism commonly exhibited by application service provider (ASP) infrastructures, where the application access point is replicated over a large number of geographically distributed edge servers. At this purpose, we allow privileged classes of users to concurrently contact multiple, replicated access points so to increase the probability to timely reach at least one of them and to promptly activate the application business logic for the interaction with a back-end database system. We complete our proposal with an efficient mechanism that prevents multiple, undesired updates on the back-end database and, at the same time, strongly limits the additional load on the ASP infrastructure due to the increased amount of requests from the privileged users.