Service-based development has attracted an increasing number of practitioners over recent years. The use of standard component technologies and more recently web services enable the construction of software systems by combining the individual services provided by a number of independent functional entities, called components.

Several approaches to service-based development have been proposed recently, most of them based on the standard modelling notation Unified Modeling Language (UML). These approaches are usually complex because they are general purpose. In this sense, this paper presents a methodology for the design of service-based applications based on UML that is both simple and systematic, and yet comprehensive. The paper also presents some guidelines for design refinement assessment.