These are flashcards an notes made by students on topics like 'catalog', 'relationship' and 'composition', originating from:

- Michael Jesse Chonoles
ISBN-10 0128096403 ISBN-13 9780128096406
1335 Flashcards & Notes
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Study Cards on catalog, relationship, composition

So far, except for the example with the datatype, we have modeled all the associations and links in this chapter as having symmetric strength.

What is symmetric strength?
That is, the two ends of the relationship, the roles, each an equivalently strong relationship to the other side.

We can consider the author:Person as an attribute of Book, just as we can consider the myBook:Book as an attribute of Person.
What is Asymmetric strength?
If we wish to indicate an asymmetric binding, we can model the relationship as a composition or an aggregation.

UML shows both relationships with a diamond (a solid diamond ♦ for COMPOSITION and

a hollow diamond for AGGREGATION),

which is placed in-line with the association and adjacent to the dominant side.
One possible way of looking at the differences between composition and aggregation is to compare physical parts vs catalog parts, check Fig. 10.27.
On the right side of the figure, we placed a Car in a catalog.

A catalog is a logical structure and not a physical structure.

In a catalog, a particular wheel model may be shared across many car models.

Therefore, the wheels are shared aggregation on the right, but a composition on the left.
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