Service orientation (SO) is a relevant promising candidate for accommodating rapidly changing user needs and expectations. One of the goals of adopting SO is the improvement of reusability, however, the development of service-based system in practice has uncovered several challenging issues, such as how to identify reusable services, how to determine configurations of services that are relevant to users’ current product configuration and context, and how to maintain service validity after configuration changes. In this paper, we propose a method that addresses these issues by adapting a feature-oriented product line engineering approach. The method is notable in that it guides developers to identify reusable services at the right level of granularity and to map users’ context to relevant service configuration, and it also provides a means to check the validity of services at runtime in terms of invariants and pre/post-conditions of services. Moreover, we propose a heterogeneous style based architecture model for developing such systems.