After
import, the association class construct has changed so that the association,
the associated class (AC), and the relationship (dashed line) are represented
by one single element: an AssociationClass element named AC. In UML 2.0, an
AssociationClass element is both an association and a class, and it is displayed
as both on diagrams. Several other important changes also take place during
the import process:
- Because multiple XDE elements are merged into a single UML 2.0 element,
you have less control over the display of association classes on diagrams.
For example, the characteristics of the dotted line connecting the association
with the class, such as color and bend points, are not imported because there
is no element in UML 2.0 to which those characteristics can be applied.
- In most cases, the XDE class that is part of the association class is
transformed into the UML 2.0 association class and no longer exists as a separate
class. If the class and the association live in different models, the class
is migrated separately and its contents are merely copied into the association
class. The diagram in the following figure capture shows an example of the
latter, where the class is copied rather than transformed.
- If an XDE class uses a generalization relationship (as an association
class) to connect to a regular class, the generalization relationship is migrated
as a dependency relationship because an association class cannot specialize
a regular class in UML 2.0.
Important: These screen captures reflect how the diagram
imports when you select the Always retain XDE class option
in the Import Options page of the XDE Model
Import wizard. When you select this option, the XDE class imports
as UML2 Class even though its contents are copied into the newly created UML
2.0 AssociationClass (which combines the Association and AssociatedClass relationships
from XDE). If you select Retain XDE Class only if needed,
the XDE association, class and AssociatedClass relationship import as a UML
2.0 AssociationClass (when the association and class reside in the same XDE
model).