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Short

Use Associations for Classes and Attributes for DataTypes

Purpose

Make an informed choice between Attributes and Associations when modeling a relation between two Classifiers.

Details

When modeling the structure of your system there are basically two ways to express a structural relationship between two Classifiers. You could use an Association between the two Classifiers, or you could create an Attribute owned by one Classifier with it’s type set to the other Classifier.

Both ways, Association or Attribute are pretty much equivalent.… Read more

What makes a UML Composition different from an Aggregation or a regular Association?

The concepts of Association, Aggregation and Composition exist in UML since the first published versions, but the exact meaning of these concepts, especially the Aggregation still leads to heated debates among UML experts.

But before we go into the details, let’s have a look at how these concepts are defined in UML. I guess every UML user is familiar with the graphical notation, but how do these concepts look like in the UML (v 2.5) meta model?… Read more