Orchestrating network services using multi-domain, heterogeneous resources / Hadi Razzaghi Kouchaksaraei ; [Referees: Prof. Dr. Holger Karl, University of Paderborn, Germany, Asst. Prof. Dr. Panagiotis Papadimitriou, University of Macedonia, Greece, Additional committee members: Prof. Dr. Stefan Böttcher, University of Paderborn, Germany, Prof. Dr. Christian Scheideler, University of Paderborn, Germany, Jun. Prof. Dr. Sevag Gharibian, University of Paderborn, Germany]