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TRAIL: Webel's ultimate guide to Systems Modeling Language (v1) with MagicDraw/Cameo

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01:03: UML Behavior: StateMachines quick start

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UML StateMachine Diagram

This content has been marked as discussing an ADVANCED topic!

NOTATION REFERENCE ONLY: This diagram is not meant to be executable!

The absence of explicit triggers or guards on Transition symbols in this diagram is for brevity only and does not imply completion Transitions with implicit triggers.

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Transitions of the kind internal are not shown explicitly in diagrams.

Transitions of type internal can however be shown in an Internal Transition compartment. For a more extensive listing of cases for local vs external Transitions please refer to UML-2.5.1 Figure 14.34 Local Transitions and Figure 14.35 External Transitions. Note however:

UML-2.5.1: 'kind = local ... However, for local Transitions the target Vertex must be different from its source Vertex. A local Transition can only exist within a composite State.'

UML-2.5.1: Has an incorrect local Transition with same source and vertex in 'Figure 14.34 Local Transitions'

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Completion transitions and implicit triggers

Notes

[ISSUE] UML-2.5.1: Has an incorrect local Transition with same source and vertex in 'Figure 14.34 Local Transitions'

Snippets (quotes/extracts)

[UML-2.5.1] A Transition represents an arc between exactly one source Vertex and exactly one Target vertex (the source and targets may be the same Vertex). It may form part of a compound transition, which takes the StateMachine from one steady State configuration...

[UML-2.5.1] internal - Implies that the Transition, if triggered, occurs without exiting or entering the source State (i.e., it does not cause a state change). This means that the entry or exit condition of the source State will not be invoked.

[UML-2.5.1] An internal Transition can be taken even if the S[t]ateMachine is in one or more Regions nested within the associated State.

[UML-2.5.1] external - Implies that the Transition, if triggered, will exit the composite (source) State.

[UML-2.5.1] local - Implies that the Transition, if triggered, will not exit the composite (source) State, but it will exit and re-enter any state within the composite State that is in the current state configuration.

[UML-2.5.1] Transitions of the kind internal are not shown explicitly in diagrams.

[UML-2.5.1] A Transition is a single directed arc originating from a single source Vertex and terminating on a single target Vertex (the source and target may be the same Vertex), which specifies a valid fragment of a StateMachine Behavior.

[UML-2.5.1] It may have an associated effect Behavior, which is executed when the Transition is traversed (executed).

[UML-2.5.1] NOTE. The duration of a Transition traversal is undefined, allowing for different semantic interpretations, including both “zero” and non-“zero” time.

[UML-2.5.1] Transitions are executed as part of a more complex compound transition that takes a StateMachine execution from one stable state configuration to another.

[UML-2.5.1] A Transition may own a set of Triggers, each of which specifies an Event whose occurrence, when dispatched, may trigger traversal of the Transition. A Transition trigger is said to be enabled if the dispatched Event occurrence matches its Event type.

[UML-2.5.1] When multiple triggers are defined for a Transition, they are logically disjunctive, that is, if any of them are enabled, the Transition will be triggered.

[UML-2.5.1] The semantics of a Transition depend on its relationship to its source Vertex. Three different possibilities are defined, depending on the value of the Transition’s kind attribute ...

[UML-2.5.1] kind = external means that the Transition exits its source Vertex. If the Vertex is a State, then executing this Transition will result in the execution of any associated exit Behavior of that State.

[UML-2.5.1] kind = local is the opposite of external, meaning that the Transition does not exit its containing State (and, hence, the exit Behavior of the containing State will not be executed). ...

[UML-2.5.1] kind = local ... However, for local Transitions the target Vertex must be different from its source Vertex. A local Transition can only exist within a composite State.

[UML-2.5.1] kind = internal is a special case of a local Transition that is a self-transition (i.e., with the same source and target States), such that the State is never exited (and, thus, not re-entered), which means that no exit or entry Behaviors are executed ...

Visit also

HOWTO simulate UML-2.5.1 'Figure 14.7 Composite State with two States' in Cameo Simulation Toolkit - Operation-driven Transition case study

HOWTO invoke an operation as a Transition guard in Cameo Simulation Toolkit

Screencast: Tutorial: UML/SysML: StateMachines vs Activities: Operation-driven Transition case study - UML-2.5.1 'Figure 14.7 Composite State with two States' in Cameo Simulation Toolkit

Screencast: Mini tutorial: UML/SysML: Cameo Simulation Toolkit: StateMachine with entry Activity and Transition guard

Screencast: Mini tutorial: UML/SysML: Cameo Simulation Toolkit: StateMachine with doActivity and a Transition with a ChangeEvent trigger

Visit also (backlinks)

HOWTO return chain on a CallBehaviorAction for an Operation trigger of a Transition with an effect

UML/SysML: HOWTO Consume a SignalEvent message in a StateMachine Transition 'effect' or State 'entry' or 'exit' Activity

Related slides (includes other tutorials)

UML2 StateMachine - metaclasses - ADVANCED REFERENCE ONLY

A quick look at accessing an Operation on a Transition or ActivityEdge guard with Alf vs ALH

UML Event types for triggering Transitions

Related slides (backlinks, includes other tutorials)

Consume a SignalEvent message in a StateMachine Transition 'effect' or State 'entry' or 'exit' Activity

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