Augmenting a Web Server with QoS by Means of an Aspect-Oriented Architecture

The handling of Quality of Service (QoS) parameters on a web server is a concern that generally spreads across the several modules responsible for fetching and delivering contents as per incoming requests. In order to avoid tangling between QoS and communication-related concerns, this paper proposes the use of aspect-orientation to handle QoS on top of an existing web server, Jigsaw. We show how an aspect-based architecture can be effective for providing the web server with several improvements when processing incoming requests. QoS parameters have been handled by associating requests with priorities and by introducing into the web server checks on resource-usage and tasks to be executed. Suggested aspects are connected at compile-time to existing classes, hence keeping the QoS-enforcing code separated from web server modules.