Transition::guard

Figure 29: State machine in SysML

Gallery

Tutorial

TRAIL: SysPhS-1.1 specification body figures in MagicDraw/Cameo SysML vs Modelica [using Wolfram SystemsModeler]

Section

Slide kind

hybrid diagram

SysML Block Definition Diagram (BDD)

SysML StateMachine Diagram

Screencast: UML/SysML StateMachines: How a completion transition works (and why you should avoid them)

Keywords

Video style

Explains what a completion transition is and how to simulate and explore it in Cameo Simulation Toolkit for MagicDraw UML, MagicDraw SysML, or Cameo Systems Modeler.

Please note that this is NOT a recommendation to use completion transitions!

UML-2.5.1 does NOT permit a trigger or guard on a Transition from an initial pseudostate in a StateMachine but Cameo/MagicDraw does (please avoid).

Transition::guard : Constraint [0..1] ... If the guard is true at that time, the Transition may be enabled, otherwise, it is disabled. Guards should be pure expressions without side effects. Guard expressions with side effects are ill formed.

Source

Unified Modeling Language 2.5.1

Transition::guard : Constraint [0..1] ... A guard is a Constraint that provides a fine-grained control over the firing of the Transition. The guard is evaluated when an Event occurrence is dispatched by the StateMachine. ...

Source

Unified Modeling Language 2.5.1

uml101 - StateMachines - NOTATION REFERENCE CARD

Gallery

Tutorial

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

Section

01:03: UML Behavior: StateMachines quick start

Slide kind

UML StateMachine Diagram

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

Gallery

Tutorial

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

Section

Slide kind

UML Activity Diagram

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

Keywords

Video style

This video accompanies this detailed tutorial trail: HOWTO simulate UML-2.5.1 'Figure 14.7 Composite State with two States' in Cameo Simulation Toolkit - Operation-driven Transition case study.

This full length tutorial is a case study of the telephone dialer StateMachine shown in 'Figure 14.7 Composite State with two States' of the UML-2.5.1 specification.

Read more about 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

The number validation guard

Gallery

Tutorial

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

Section

Slide kind

UML StateMachine Diagram

StateMachine for the Dialer class

Gallery

Tutorial

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

Section

Slide kind

UML StateMachine Diagram

Figure 14.7 Composite State with two States

Gallery

Tutorial

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

Section

Slide kind

UML StateMachine Diagram

StateMachine diagram for comparing action language access to an operation for a guard

Gallery

Tutorial

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

Section

Slide kind

UML StateMachine Diagram

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

Jump to first slide

Class diagram for comparing action language access to an operation for a guard

Sections

junction – ... If more than one guard evaluates to true, one of these is chosen. The algorithm for making this selection is not defined.

Source

Unified Modeling Language 2.5.1

choice – ... If none of the guards evaluates to true, then the model is considered ill formed. To avoid this, it is recommended to define one outgoing Transition with the predefined “else” guard for every choice Pseudostate.

Source

Unified Modeling Language 2.5.1

choice – ... If more than one guard evaluates to true, one of the corresponding Transitions is selected. The algorithm for making this selection is not defined.

Source

Unified Modeling Language 2.5.1

choice – This type of Pseudostate is similar to a junction Pseudostate ... and serves similar purposes, with the difference that the guard Constraints on all outgoing Transitions are evaluated dynamically ...

Source

Unified Modeling Language 2.5.1

NOTE. Such guard Constraints are evaluated before any compound transition containing this Pseudostate is executed, which is why this is referred to as a static conditional branch.

Source

Unified Modeling Language 2.5.1

.. a junction Pseudostate ... can be used to split an incoming Transition into multiple outgoing Transition segments with different guard Constraints.

Source

Unified Modeling Language 2.5.1

The Transitions outgoing from a fork Pseudostate cannot have a guard or a trigger.

Source

Unified Modeling Language 2.5.1

Transitions terminating on a join Pseudostate cannot have a guard or a trigger.

Source

Unified Modeling Language 2.5.1

initial - ... It is the source for at most one Transition, which may have an associated effect Behavior, but not an associated trigger or guard.

Source

Unified Modeling Language 2.5.1

Any guards associated with these entry point Transitions must evaluate to true in order for the specification to be well formed.

Source

Unified Modeling Language 2.5.1

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

Keywords

Video style

A very simple demonstration of a StateMachine with an entry Activity and Transitions that use guards to check a value. Uses SysML but the same applies to UML.

Uses Cameo Simulation Toolkit for MagicDraw SysML and Cameo System Modeler.

Subscribe to Transition::guard