Thomas Feng 1
The history of action semantics, including the pros and cons of its predecessor, denotational semantics, is briefly introduced. Comparison is made on different attempts to achieve an executable UML. The basics of action semantics, including all the defined action types, is discussed in detail. From this discussion, the conclusion is drawn that, though flaws still exist, action semantics is a powerful tool to describe behavior in the level of both modelling and meta-modelling.