As Web services composition arouses a growing interest, most research works address implementation and execution issues. As a consequence, many composition languages (BPEL, XLANG, WSFL, WSCI, to name a few of them) have been proposed in the past few years. However, a weakness of these languages is that they are difficult to use in early stages of development, such as specification. UML-S is an extension to UML 2.0 that was introduced to address this issue. UML-S allows to develop composite Web services according to model driven engineering (MDE) principles. In this paper, composite Web service development using UML-S will be described through a case study.