Date Added: May 2010
A Service-Level Agreement (SLA) provides surety for specific quality attributes to the consumers of services. However, the current SLAs offered by cloud providers do not address response time, which, from the user's point of view, is the most important quality attribute for web applications. Satisfying a maximum average response time guarantee for web applications is difficult for two main reasons: first, traffic patterns are unpredictable; second, the complex nature of multi-tier web applications increases the difficulty of identifying bottlenecks and resolving them automatically. This paper presents a working prototype system that automatically detects and resolves bottlenecks in a multi-tier web application hosted on a EUCALYPTUS-based cloud in order to satisfy specific maximum response time requirements.