Automatic QoS control

User sessions, usually consisting of sequences of consecutive requests from customers, comprise most of an e-commerce site´s workload. These requests execute e-business functions such as browse, search, register, login, add to shopping cart, and pay. Once we properly understand and characterize a workload, we must assess its effect on the site´s quality of service (QoS), which is defined in terms of response time, throughput, the probability that requests will be rejected, and availability. We can assess an e-commerce site´s QoS in many different ways. One approach is by measuring the site´s performance, which we can determine from a production site using a real workload or from a test site using a synthetic workload (as in load testing). Another approach consists of using performance models. I look at the approach my colleagues at George Mason and I took that uses performance models in the design and implementation of automatic QoS controller for e-commerce sites.