One key factor for successfully outsourcing of applications to a provider is to guarantee a certain level of service. Hence, service provider and service consumer agree on Service Level Agreements (SLA) that definne the behavior and quality of the non-functional properties. Unlike many existing approaches, which only allow the customer to choose between a small set of predefined service levels, our approach helps to cope with the situation that customers want to model their own service level according to their individual business needs. As a first step, we introduce an application model which enables the outsourcing of applications. In addition, we present corresponding models for describing QoS requirements and SLAs. To assure the requested QoS, the provider has to determine the QoS requirements of each application component. In this work, we determine the QoS requirement of a component by disaggregating the QoS requirements stated in the SLA. After the disaggregation the provider deploys each component of the application in an optimal way based on its QoS requirements, determined during the disaggregation.