Web Service Availability ― Impact of Error Recovery

摘要

Growing usage and diversity of applications on the Internet make the issue of assessing the web service availability increasingly important. The Internet is often used for transaction based applications such as online banking, stock trading, shopping, where the service interruption or outages are unacceptable. Therefore, it is important for the developers of such applications to analyze during the design phase how hardware, software and performance related failures affect the quality of service delivered to the users. This paper presents analytical models in order to study the availability of web services implemented on web clusters. In particular, a composite performance and availability modeling approach is considered where various causes of service unavailability and two different recovery strategies are taken into account. For illustration purposes, sensitivity analysis results are presented to show the impact on the web service availability of various assumptions concerning the architecture, the servers load, as well as the failure and recovery processes.