[Uml-devel] UML question

[P. Fleury]

Hi Anthony,

I also think that an aggregation give an information about the relations 
of the life-time of the related objects. Hence the filled and unfilled 
diamonds in some relations (aggregation is filled). The 1..* relation 
does not indicate any life-time issue, and my understanding of UML is 
that you can use it for things which can be dynamically associated. This 
also matches your car+wheel+people example.

--pascal

Lea Anthony wrote:

>Hi Steinchen,
>
>What I mean is, there is a definate distinction between relationships and 
>aggregations. Relationships have straight lines and aggregations are the same 
>but with diamonds on the end. So given that, what's the difference between a 
>1 to many relationship and a 1 to many aggregation. I think the answer is 
>that a class exists in it's own right when a 1 to many relationship is used, 
>but when an aggregation is used, it means the class is _comprised_ of that 
>aggregate too. 
>
>I think, a car would have a 1...*  aggregation of wheels, but not a 1...* 
>aggregation of persons. 
>
>If that makes any sense...
>
>-Lea.
>
>On Sunday 25 May 2003 19:05, Sebastian Stein wrote:
>  
>
>>Lea Anthony <lea at fluidenterprises.co.uk> [030523 19:51]:
>>    
>>
>>>I've been looking at UML more lately and have a simple question: What's
>>>the difference between a 1..* relationship and an aggregation?
>>>      
>>>
>>Well, I'm not really sure what you mean, because I think you are mixing
>>some things... 1..* is called multiplicity (better known as cardinality).
>>An aggregation could have 1..* multiplicity. This means, that class A could
>>have an unfinite number of objects of class B.
>>
>>Steinchen
>>    
>>
>
>
>
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