Service-centric systems exist in a very dynamic environment, which requires these systems to adapt at runtime in order to keep fulfilling its QoS requirements to its users. In order to create self-adaptive service centric systems, developers not only design the service architecture, but need to design the self-adaptability aspects in a structured way. Current service standards and technologies do not provide a general architecture in which all aspects for self-adaptability can be designed. In this paper we propose DySOA (Dynamic Service-Oriented Architecture), an architecture that extends service-centric applications to make them selfadaptive. DySOA allows developers to explicitly model the process and components that deal with determining the QoS of the running system, with evaluating the QoS, and with reconfiguring the system when necessary. Having the DySOA elements explicit enables separation of concerns, making the DySOA elements adaptable at runtime and reusable in next versions. We demonstrate how to use DySOA with an example.