Simulation Approach to Decision-Making

One of the main objectives of the ITIL strategy of IT services process is to define the strategic goals of organizations and the appropriate strategies for compliance. Strategic goals can be expressed in the form of different managerial business rules that aggregate different business rules that affect the structure and behavior of the services. Thus, the fulfillment of the business rules determines the fulfillment of the strategic goals. In this paper we focus on the business rules that indicate restrictions about services behavior. These business rules figure in the contracts service providers and their clients sign called service level agreement (SLA).

For the purpose of this study, we have considered a hypothetical e-commerce company that sells products on the Internet. The e-commerce company is a distribution company that buys the products to their manufacturers and sells them to their customer through the company website.

In SOA approach, the tasks that validate credit card details and verify that company's customers possess enough credit to make the purchase are handled by the credit card validation service provided by a banking validation service provider. In this context, the e-commerce company and the service provider sign a SLA in which issues such as service capacity contracted, service availability, service response time, service abandon rate, key performance indicators, and operation or billing model are set, among others. The billing model and the quantity the company has to pay to the service provider depend on the values estimated and specified for the SLA parameters. Errors in the estimation of these parameters will have a direct effect not only on the bill but also on the fulfillment of both business rules and strategic goals of the service provider.

With the aim of helping service providers in the decision-making process to define their strategic goals, a simulation model is built to allow evaluating the effects of different service capacities and service request tendencies on the fulfillment of our business rule and hence the strategic goal customer satisfaction.

In this study, we have focused mainly on the business rule that specifies the maximum percentage of service requests that are permitted to be abandoned (15%) because they have exceeded the waiting time established. Consequently, we have considered the SLA parameters most frequently used to define this business rule.

It is important to notice that we have focused only on the service requests rejections due to the delay in the response of the service for more than the maximum response time allowed by the company. We have not considered other reasons for service requests rejections such as server down, incorrect credit card data, and insufficient balance of the credit card, among others.