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Message:

aggregation relationship in java

Posted by saqer on October 30, 2001 at 10:21 AM

> For a short discussion on this topic that packs in more than you ever
> wanted to know about it, look at an article by Brian
> Hendersen-Sellers in JOOP, the Nov-Dec. 97 issue.

> I heard Brian make a talk on the OPEN methodology and modeling
> language, where he
> distinguished between aggregation/composition (a whole made up
> of two or more parts in some configuration
> where the relationships are important -- e.g. you have to put the parts
> of a sailboat together in the right order for it to be useful),
> membership (a whole made up of one or more parts but in no particular
> relationship to each other -- e.g. a club of people), and containment (I
> suppose here there is even less connection between the parts, as
> with a bus filled with passengers).

> The OPEN notation includes symbols for each of the above. The one for
> aggregation/composition is a circle with a plus sign in it, intended
> to resemble a Phillips-head screw used to assemble things together.
> UML's open and filled diamonds don't get much respect in OPEN circles.

> The above-mentioned article also discusses relationships like
> stuff-object (a bicycle is partly steel, cappuccino is partly
> milk), portion-object (a slice of bread is the same substance as
> the entire loaf), place-area (Austin is part of Texas), member-bunch
> (a tree is part of a forest), member-partnership (an invariant
> form of the previous category; Ginger and Fred are a dance couple).
> The bibliography for the article lists sources for further reading,
> including one called "A Taxonomy of Part-Whole Relations."