The Publish-Discover-Compose paradigm of Service- Oriented Computing (SOC) presents a new challenge on the service applicability and adaptability. Services in SOC are not just for dedicated service clients, rather for a group of diverse and unknown potential service clients. Hence, service providers try to develop and publish services which can be applicable to various potential clients. Service clients try to locate right services without knowing much about service providers in advance. A challenging problem with this little coupling between providers and clients is that available services should be highly adaptable to various service clients and various service contexts. To develop such adaptable services, the service variability among potential clients and contexts must carefully be analyzed and designed. However, current works on service oriented analysis and design (SOAD) largely focus on defining processes for developing business processes and services without considering variability in details. In this paper, we analyze the key artifacts of common SOAD methods and identify types of variation points over the artifacts. Then, we present a systematic SOAD process for developing highly adaptable business services. We also present a case study to show the feasibility of the process. By developing adaptable services by using our proposed framework, the applicability and reusability of such services can be increased.