The idea of the future internet of services is to combine several services of numerous service providers to new value-added services or applications. To sell these services on so-called service marketplaces the providers have to ensure a high quality of service execution. But how could a provider of a composed service ensure the quality of the whole application, if single services of other providers fail or do not reach the required level of quality? This article describes an approach for modeling adaptation in web service compositions to ensure a guaranteed quality of service for the whole composite service. A special adaptation mechanism is the rebinding of single services while the process is executed if the services fail or could not reach the needed QoS level. We will present a solution for modeling these rebinding concepts in BPEL processes and the infrastructure to support this adaptation mechanism at run-time.