The UML as a Formal Modeling Notation

The Uni ed Modeling Language UML is rapidly emerging as a de facto standard for modelling OO systems Given this role it is imperative that the UML needs a well de ned fully explored semantics Such semantics is required in order to ensure that UML concepts are precisely stated and de ned In this paper we motivate an approach to formalizing UML in which formal speci cation techniques are used to gain insight into the semantics of UML notations and diagrams and describe a roadmap for this approach The authors initiated the Precise UML PUML group in order to develop a precise semantic model for UML diagrams The semantic model is to be used as the basis for a set of diagrammatical transformation rules which enable formal deductions to be made about UML diagrams A small example shows how these rules can be used to verify whether one class diagram is a valid deduction of another Because these rules are presented at the diagrammatical level it will be argued that UML can be successfully used as a formal modelling tool without the notational complexities that are commonly found in textual speci cation techniques