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I am bit new to all this UML, so I hope you all would bear with me and my rookie question.

During OOA when you'll alway draw a domain model. It shows the concepts, it's attributes, and the relations (association) between each concepts.

But I haven't understood Whole - to - part associations yet. As far as i've understood, it has something to do with a concept beeing associated to multiple concepts, am i right?..

And is it possible to aggregate an association, or is it strictly concepts which can be aggregated???

My confusing may be due to the fact that i am bit unclear on when to use aggregation in the first place...?? could someone clarify it for me??

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Your question is vague, but let's start here from IBM's description:


Search for aggregation and composition.

Basically, aggregation is used for a class with multiple dependent components, like a car and its parts. When a car is totaled, the wheels can be removed. The wheels and may have other purposes (inventoried, repaired, recycled, etc.). Composition exists when a component's lifecycle is dependent on the parent class lifecycle. An example of composition is a business and its operations (like its loading dock). When the business closes, the loading dock is no longer necessary so both instances are deleted.

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Is it like having a class (concept) called animal and from animal it has attributes. Each attribute can bee seen as an component?? To be more specifik about my question, does Aggregation only apply to classes, or also association between classes (Consepts) –  user3139171 Dec 27 '13 at 17:11
Not like an animal and its attributes. The attributes are the variables of a given class. Aggregation is an association between classes. It's really a question of how complex your system is. If you have multiple non-trivial components then you model can model each component as associated classes. I would suggest reading a book about object oriented analysis and design. This type of problem is well understood and described. –  Bruce Dec 27 '13 at 18:14
But could an aggregation or composition exist for an association. –  user3139171 Dec 28 '13 at 11:05
Aggregation and composition are forms of association. One would not associate associations. One associates classes, components, subsystems, and systems. –  Bruce Dec 28 '13 at 19:05
Could you do anything on an association?? –  user3139171 Dec 30 '13 at 14:28
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