The high competition among network providers places a demand for new ways to design network services with near zero development time, low cost, and high degrees of customization and evolution. Customization allows to fit the service according to the customers’ requirements, while evolution allows to adapt the service as soon as these requirements change. Moreover, customers are demanding the ability to manage the contracted services in order to keep service usage, configuration, and evolution under their control. This paper presents an approach based on service oriented architecture (SOA) for developing network services able to fulfill the requirements of rapid development, customization, and customer-side manageability. The approach considers the network service as the composition (orchestration) of a set of basic services. A generalization of the architecture primarily aimed at connection oriented networks is introduced, extending it to overlay networks. Two services for the management of tunnels on optical networks are presented as a case study.