This paper proposes and illustrates an
approach to identify and specify requirements on
information-based business services and their associated
derived software services. The approach proposes first
to identify business services by modeling business
requirements using the goal oriented modeling notation
i*. Then, in a second phase, the identified services are
refined according to these requirements using UML
activity and class diagrams. This specification is based
on a method and a supporting toolset, called "Efficient".
The approach is illustrated through the handling of a
case study in the tourism sector.