This thesis contributes to the business-driven management of IT systems at different levels. First, a management framework that links together business goals, Service Level Agreements (SLAs), and policy operation is proposed. Then existing policy and SLA specification formalisms are investigated and a specification for SLAs that is policy-driven is proposed. The major contribution of the thesis relates to policy analysis mechanisms. This work contributes to the off-line analysis of low-level policies for validity and consistency with regard to high-level goals and SLAs. On one hand, a policy test type is identified that helps in detecting a new type of abnormal behavior we name policy loops. Neither detecting nor resolving this type of behavior is easy to do in the general case. This work however shows how it can be done for the studied example application. Moreover, a new type of analysis is proposed, that we name policy dynamic analysis, which corresponds to the investigation of how to influence the scheduling of policy execution at runtime so as to achieve better optimization of the high-level business goals. Finally, this work identifies the critical need for simulating policy solutions and presents PS, which is a policy simulator tool that we developed for the purpose of experimenting, analyzing, validating, and optimizing policy solutions before they get to their actual deployment into a real scale environment. Business-driven management is a management paradigm wherewith low-level system configuration actions are derived and operated with a focus on fulfilling and optimizing the initial high-level business goals of a service provider. A set of requirements is needed for enabling such a management paradigm. These include the ability to specify high-level business goals and Service Level Agreements (SLAs), the refinement of these goals and SLAs into low-level configuration actions, as well as the validation of these low-level actions against the specified high-level behavior. A subsequent monitoring loop helps in enhancing future system performance by identifying and remedying defects learned from past operation. Policy-based management has emerged as a preferred mechanism for implementing business-driven management due to the promise to alleviate the configuration and maintenance cost of complex computerized systems by providing a management model that separates implementation functionality from the behavioral logic. Although there has been considerable effort in industry and academia regarding the specification and implementation of policies and SLAs, little focus has been given to the refinement of high-level goals into low-level policies. The interest in the investigation of policy refinement has gained interest only recently. Furthermore, there is a need to investigate the runtime behavior of policy and develop models and techniques that take the goal-oriented policy refinement a step further by considering the dynamics of policy behavior at runtime and how these can relate to the optimization of high-level business goals. This thesis contributes to the business-driven management of IT systems at different levels. First, a management framework that links together business goals, Service Level Agreements (SLAs), and policy operation is proposed. Then existing policy and SLA specification formalisms are investigated and a specification for SLAs that is policy-driven is proposed. The major contribution of the thesis relates to policy analysis mechanisms. This work contributes to the off-line analysis of low-level policies for validity and consistency with regard to high-level goals and SLAs. On one hand, a policy test type is identified that helps in detecting a new type of abnormal behavior we name policy loops. Neither detecting nor resolving this type of behavior is easy to do in the general case. This work however shows how it can be done for the studied example application. Moreover, a new type of analysis is proposed, that we name policy dynamic analysis, which corresponds to the investigation of how to influence the scheduling of policy execution at runtime so as to achieve better optimization of the high-level business goals. Finally, this work identifies the critical need for simulating policy solutions and presents PS, which is a policy simulator tool that we developed for the purpose of experimenting, analyzing, validating, and optimizing policy solutions before they get to their actual deployment into a real scale environment.
A Business-Driven Approach to Policy Optimization