A Hospital information system (HIS) has been proposed to respond to some challenges of the complex business process in a hospital. The business processes undergo constant change and the HIS needs to swiftly adapt to reflect these changes. This paper proposes an approach, which is used to define services and solutions for hospital applications according to the business-entity changes in the hospital business processes. The objective of this approach is to minimize the effect of business requirement changes on the system development. Focusing on the transition from the process-oriented to the application-oriented perspectives, some central development considerations are also presented, which can be used to guide the design of service-based interoperability and illustrate these aspects with examples from our current work. This solution will improve the robustness and extensibility of HIS.