Modeling the Dynamics of UML State Machines

Abstract

Abstract. We define the dynamic semantics of UML State Machines which integrate statecharts with the UML object model. The use of ASMs allows us (a) to rigorously model the event driven run to completion scheme, including the sequential execution of entry/exit actions (along the structure of state nesting) and the concurrent execution of internal activities; (b) to formalize the object interaction, by combining control and data flow features in a seamless way; and (c) to provide a precise but nevertheless provably most general computational meaning to the UML terms of atomic and durative actions/activities. We borrow some features from the rigorous description of UML Activity Diagrams by ASMs in [7].

On Integrating Structure and Behavior Modeling with OCL

“…For a TrafficLight class with three boolean attributes representing the red, yellow, and green bulbs, a protocol state machine allows the traffic light to step through four phases, where each phase is represented by a single state and a state invariant in form of an OCL expression characterizing the signal in terms of the bulbs. 2 The object diagram shows four test traffic lights equipped with randomly determined attribute values for the bulbs, not all representing valid signal configurations. The attribute values have been modified not by operations, but with direct attribute assignments.…”

“…However the authors refer to an older UML version, whereby postconditions of protocol state machine transitions are not handled. The dynamic semantics of state machines is discussed in [2]. Usage of State Machines.…”

An ASM Semantics of UML Derived from the Meta-model and Incorporating Actions

“…on several threads. 2 The active object's state machine may receive call events, but only if they do not correspond to calls directed towards the current active object. This is to avoid the situations when the target object could ignore a call.…”

“…Some UML formalization efforts using ASM already exist: [3] formalizes UML activity diagrams, by adapting ASM to natively support activity diagrams; [2] formalizes UML state machines by extending the basic ASM, with some new constructs to cover UML state machines specific features; [4] defines an ASM based toolset, focused on the state diagrams. These approaches disconnect state machines /activity diagrams of the rest of the language, and they do not consider all UML concepts (associations, inheritance, etc.…”

Abstract State Machines at the Cusp of the Millenium

“…But this year brought us a theoretical explanation of the observed phenomenon, namely via a proof [25] that the sequential version of the thesis follows from three fundamental system theory axioms. Once established, the thesis allows one to draw conclusions of practical importance, as is illustrated by an example in these Proceedings [7]: the thesis guarantees that there is no loss of generality in substituting the fundamental but vague UML concepts of action and activity by the mathematically rigorous concepts of ASM step and ASM run. It seems that in UML [31,2] the meanings of action/activity were intentionally left unspecified, namely to leave the space of possible implementations as open as possible.…”