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composite aggregation [message #628223]

Wed, 10 February 2010 00:57

Hector Chavez

Messages: 34
Registered: February 2010

Member

Hi, I have a question about the composite aggregation. If we have the following case:

classA::target:B
classB::source:A

I normally would assume that setting the aggregation to composite on the target will result having a black diamond right next to classA, is that correct?

If that is the case... I found this text in the UML Spec v2.2. on page 42 that says:

"... An association with aggregationKind = composite likewise has a diamond at the aggregate end... "

Doesn't that mean that the diamond should be on the target(right next to classB instead of classA)?

I'm confused about this statement.

Thanks for the help!!

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Re: composite aggregation [message #628225 is a reply to message #628223]

Wed, 10 February 2010 12:43

Vlad Varnica

Messages: 546
Registered: July 2009
Location: Milton Keynes - UK

Senior Member

What is important is to have the good information in the association property which is saved in the model. Look in the Property View to check it.
In the association creation wizard it is just a question of being or not used.

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Re: composite aggregation [message #628229 is a reply to message #628225]

Wed, 10 February 2010 21:58

Hector Chavez

Messages: 34
Registered: February 2010

Member

I'm sorry, I don't think I get what you are trying to tell me.

I'm just trying to understand the meaning of the statement. It seems to me that the way models are set up and what the UML specification says about the placement of diamond is not consistent.

When they say "diamond at the aggregate end" wouldn't that be right next to classB if we set the composite on the target(classA::target:B[composite])?

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Re: composite aggregation [message #628230 is a reply to message #628229]

Thu, 11 February 2010 11:29

Vlad Varnica

Messages: 546
Registered: July 2009
Location: Milton Keynes - UK

Senior Member

Hi Hector,

I have created a small video on the association :d
This video explains how should be saved a standard association, an aggregation & composition in the UML Editor, the property view and in the model (e.g. the xmi metamodel).
It also explain that the full association information is contained in the association end attribut and not in the association itself.

See the 2minutes video at:
Flash demo: http://www.download-omondo.com/AggregationAndComposition.swf
exe file for windows: http://www.download-omondo.com/AggregationAndComposition.exe
hqx file for Mac: http://www.download-omondo.com/AggregationAndComposition.hqx

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Re: composite aggregation [message #628231 is a reply to message #628230]

Thu, 11 February 2010 11:56

Carsten Reckord

Messages: 139
Registered: July 2009

Senior Member

Hi Hector, Hi Vlad,

Vlad: I think what Hector is confused about is the term 'aggregate end' being used with regard to the Property (in your example class9) vs.
the (perhaps more intuitive) notion of the "aggregate class" (Class10).

Hector: I think this is a bit of a wording problem in the Superstructure. I agree that the notion of class B being the "aggregate end" is
more intuitive when looking at the diagram, but the Superstructure is explainging this in terms of the Properties making up the association
ends. So, in your example the 'target' property is specified as aggregation, making it the aggregating end of the association and 'source'
the aggregate end. Therefore, in terms of the involved properties, the diamond really is shown at the aggregate end (since 'source' is shown
next to class 'A', where the diamond is).

HTH,
Carsten

On 11.02.2010 12:29, Vlad Varnica wrote:
> Hi Hector,
>
> I have created a small video on the association :d
> This video explains how should be saved a standard association, an aggregation & composition in the UML Editor, the property view and in the model (e.g. the xmi metamodel).
> It also explain that the full association information is contained in the association end attribut and not in the association itself.
>
> See the 2minutes video at:
> Flash demo: http://www.download-omondo.com/AggregationAndComposition.swf
> exe file for windows: http://www.download-omondo.com/AggregationAndComposition.exe
> hqx file for Mac: http://www.download-omondo.com/AggregationAndComposition.hqx
>
>

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