Services based application and services compositions are used to improve cooperation between companies to increase the adaptability of information systems (IS) architecture.However, services as well as services compositions are designed in such a way that quality of services (QoS) policy cannot be dynamically adapted to the users needs. In fact, services and services compositions encapsulate the domain-specific business logic served by company IS, and orthogonal requirements called quality of services such as security, logging, and transaction. To adapt, in a dynamic way, the QoS to the business-logic of services in the services composition, we propose to deal with two kinds of services; business and quality early in the process. In this paper, we propose an intentional process that enables to differentiate a business service and quality of service, in a goal driven manner. The QoS is considered as a potential aspect. The paper presents the approach and illustrates it with a medical case study.