Web performance modeling issues

The Web has experienced phenomenal growth and has become an important element of the information infrastructure of many organizations. Web performance and around-the-clock availability are the major concerns of Webmasters of sites that support mission-critical applications, such as electronic commerce, Web sites are complex computer systems consisting of many interconnected computers, networks, and routers. Some of the computers have specific functions such as authorization or caching. Workloads on Web sites are often unpredictable in nature. Heavy-load spikes and a large variability of the objects requested over the Web are unique characteristics of Web workloads. This paper reviews the important issues and challenges in modeling Web-based systems. Workload characterization, predictive models, and their use in various situations are discussed.