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Instances for StateMachine::Trigger [message #478043]

Wed, 03 December 2008 12:44

Timothy Marc

Messages: 547
Registered: July 2009

Senior Member

Hey UMLer,

i have a question concerning the assignment of instance value (arguments) to
a transition in a StateMachine. In an Interaction, one can add arguments
(ValueSpecifications) to each messages, which are passed through the
Lifelines. Now, i have to model a similiar semantical behavior to
StateMachine. But i was wondering, that you can in fact define an operation
for a trigger, but it is not possible, to assign concrete instance
specifications or even values to a trigger.

I only found such a assignment-specification in the UML specification, that
points to a attribute in the owningClassifier of the StateMachine, but i
didn't get the idea behind this...

Any help would be appreciated.

Thx
Timothy

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Re: Instances for StateMachine::Trigger [message #478049 is a reply to message #478043]

Sun, 07 December 2008 16:03

james bruck

Messages: 1724
Registered: July 2009

Senior Member

Hi Timothy,

Although not exactly what you are looking for, you may want to have the
transition reference a trigger that in turn references a ChangeEvent. The
change expression is a ValueSpecification.

Another possible alternative is to use the guard of the transition. A guard
refers to a Constraint which in turn references a specification.

There however, doesn't seem to be an exact parallel to the arguments on
Message in a sequence diagram in the state machine semantics. Perhaps
consider using an Activity diagram and ValueSpecificationAction or use a
combination of StateMachine and Sequence diagram to fully describe your
model. The Event you use in the Sequence diagram would be the same used in
the StateMachine.

You mention that you saw something in the spec that may provide a clue.
What section were you looking at specifically?

Cheers,
- James.

"Timothy Marc" <timothymarc@freenet.de> wrote in message
news:gh5uqh$2ji$1@build.eclipse.org...
> Hey UMLer,
>
> i have a question concerning the assignment of instance value (arguments)
> to
> a transition in a StateMachine. In an Interaction, one can add arguments
> (ValueSpecifications) to each messages, which are passed through the
> Lifelines. Now, i have to model a similiar semantical behavior to
> StateMachine. But i was wondering, that you can in fact define an
> operation
> for a trigger, but it is not possible, to assign concrete instance
> specifications or even values to a trigger.
>
> I only found such a assignment-specification in the UML specification,
> that points to a attribute in the owningClassifier of the StateMachine,
> but i didn't get the idea behind this...
>
> Any help would be appreciated.
>
> Thx
> Timothy
>
>
>

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Re: Instances for StateMachine::Trigger [message #478050 is a reply to message #478049]

Sun, 07 December 2008 19:32

Timothy Marc

Messages: 547
Registered: July 2009

Senior Member

Hey James,

the section i mentioned was 13.3.25 SignalEvent, in the notation
subsections, the following was specified:

"Signal events are denoted by a list of names of the triggering signals,
followed by an assignment specification:
<signal-event> ::= <name> [‘(‘ [<assignment-specification>] ‘)’]
<assignment-specification> ::= <attr-name> [‘,’<attr-name>]*
where:
• <attr-name> is an implicit assignment of the corresponding parameter
of the signal to an attribute (with this name) of
the context object owning the triggered behavior.
• <assignment-specification> is optional and may be omitted even if
the signal has parameters."

The best "hack" you suggested is, in my opinion, the guard variant, but
this would only work, if the transition doesn't specifiy a "normal"
Constraint.

I was wondering, that StateMachines doesn't seem to be intended to
specifiy concrete ValueSpecification for a Call operation or Signal
reception...

Timothy

James Bruck schrieb:
> Hi Timothy,
>
> Although not exactly what you are looking for, you may want to have the
> transition reference a trigger that in turn references a ChangeEvent. The
> change expression is a ValueSpecification.
>
> Another possible alternative is to use the guard of the transition. A guard
> refers to a Constraint which in turn references a specification.
>
> There however, doesn't seem to be an exact parallel to the arguments on
> Message in a sequence diagram in the state machine semantics. Perhaps
> consider using an Activity diagram and ValueSpecificationAction or use a
> combination of StateMachine and Sequence diagram to fully describe your
> model. The Event you use in the Sequence diagram would be the same used in
> the StateMachine.
>
> You mention that you saw something in the spec that may provide a clue.
> What section were you looking at specifically?
>
> Cheers,
> - James.

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