This paper stresses out the principles of abstraction, specialization, and separation of concerns in addition to the role of service-oriented architecture in smoothing the modelling and design of business processes by reducing the complexity and achieving the flexibility of these processes. A business process is considered as an artefact entity that is implemented using a set of concrete activities. The coordination of these activities happens through a state that reflects the execution progress of the business process. The activities and data that a business process requires are made available through specialized components known as business objects. The control of a business process, its state, its activities, and the data it requires are assigned to different services. Because of the multiple perspectives (e.g., design, invocation, and tracking) from which a business process can be examined, services are specialized into two types, namely Web service and data service. As a result, this specialization makes a business process flexible, reduces the complexity of controlling and coordinating its activities, and reinforces the access controls over these activities.