Innovation in technologies such as XML and Web Services, has led to an interest in business processes. Consequently, several languages for the execution of business processes have been created. Nevertheless, as these languages cannot be used in the early stages of the development process of Web information systems (WIS), it is necessary to include methodologies that allow the systems analysts to understand the business process as well as to model the services composition. This work presents a process for the business process development based on Web Services, which starts with the identification of the services that will be offered to the user and ends with the definition of a service composition model. This process is illustrated by means of a WIS for the management of medical images that we have taken as a case study. Because it is one of the most widely used for Web services composition, we have chosen the BPEL4WS language for the implementation of the business processes. However, we have found several limitations in such language which are also described in this paper.