UML was initially created as a general-purpose modelling language. As the UML developed and spread successfully, approaches to using UML not only as a modelling tool but also as a model-driven development (MDE) solution, were developed. But classical UML models are not always suitable for MDE because of imprecise semantics. The OMG offers for executable models the use of a special subset of the UML (Foundational UML Subset) and its textual counterpart (Action Language for fUML). The model can be described in both graphical and textual representations, transformed into each other. What can be the advantage of this approach? How will it affect the life cycle of software development? What roles will be required to organise such a process? Will the tasks of the analyst change?