Re: Relationship between regions and transitions



Re: Relationship between regions and transitions

From: Tony Simons <A.Simons_at_dcs.shef.ac.uk>
Date: Mon, 11 Dec 2006 14:26:20 +0000 (GMT)
Message-Id: <200612111426.kBBEQKrb009887@holly.dcs.shef.ac.uk>
In reply to Alessandro:

> I need a clarification about the State Machine Diagrams. I have read the UML
> 2.0 Superstructure specification and I can't understand how the relationship
> between regions and transitions exactly works.
> 
> I have found the specification of a previous version of UML. Regions were
> not present and it explains the realtionship between StateMachine e
> Transitions in this way:
> 
> "Transition Associations: Associates the StateMachine with its Transitions.
> Note that internal Transitions are owned by the State and not by the
> StateMachine. All other Transitions which are essentially relationships
> between States are owned by the StateMachine. Multiplicity is '0..*'. "
> 
> Anyway maybe this concept is still valid and the transitions are contained
> by the top-level region, but it's not really well defined. Talking about
> region's associations the Specification 2.0 says: "Transition: The set of
> transitions owned by the region. Note that internal transitions are owned by
> a region, but applies to the source state."
> 
> Is it correct if I consider that the transitions are contained by the
> top-level region?
> 
> Thank you.
> 
>   Alessandro


I think that the basic notion of a 'region' comes from the idea that a
composite state may consist of one or more regions (more, if there are
parallel substate machines).  In UML 2.0 the notion of region also seems
to relate to the extension of state machines, whereby you show an extended
state in dotted outline as a region of interest in which further substates
or transitions are defined.  I would find it consistent to assume that
the transitions of the top-level states exist within a top-level region
bounded by the top-level diagram.

--Tony





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Dr Anthony J H Simons                   a.simons@dcs.shef.ac.uk
Senior Lecturer in Computer Science     http://www.dcs.shef.ac.uk/~ajhs

Department of Computer Science          tel:  (+44) 114 22 21838
University of Sheffield                 dept: (+44) 114 22 21800
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Received on Mon 11 Dec 2006 - 14:26:23 GMT