Formal Action Semantics for a UML Action Language

The abstractsyntax and static semantics of UML, the widely-used general- purpose graphical modeling language, have been standardized in a four-layer meta- modeling framework. However UML’s dynamic semantics, such as UML Precise Action Semantics and the behaviors like activities, interactions and state machines, are only standardized in a naturallanguage—English. It is commonly argued that suchinformal description inevitably involves ambiguities and lacks rigorousness, precluding the early simulation and reasoning about a UML system design. Here we select Action Semantics (AS)as the vehicle to formalize UML. AS is a mature semantics description framework which has advantages of intelligibility, modularity and practicability. In our approach, we formalize UML indirectly by formalizing its textual correspondent—an extended Action Language, which plays a key role as the interface between UML and its action semantics.