Developing a DSL Graphical Notation - Eclipse Modeling Project: A Domain-Specific Language Toolkit - page 198

Our Aggregation link is similar to a regular association, except for the ini-
tialization of the aggregation property to true and the hollow diamond decora-
tor at the source end. Another difference is with respect to link constraints,
which here prevents aggregation relationships from being created to archetypes
of differing type. The exception is the most common aggregation relationship in
color models—that is, between a Moment Interval and a Moment Interval
Detail. Table 4-42 shows the mapping.

Table 4-42 Aggregation Link Mapping

Element Property Value

Mapping

Link Mapping Containment Feature Class.features : StructuralFeature

Element Association → Reference

Target Feature TypedElement.type : Classifier

Diagram Link Connection Aggregation

Tool Creation Tool Aggregation

Constraint Body self.aggregation = true

Language ocl

Feature Seq Initializer Element Class Association → Reference

Feature Value Spec Feature Association.aggregation : EBoolean

Value Expression Body true

Language ocl

Feature Value Spec Feature TypedElement.upperBound : EInt

Value Expression Body -1

Language ocl

Feature Value Spec Feature Reference.opposite : Reference

Body Same as body above

Language java

Feature Value Spec Feature Reference.bidirectional : Boolean

Body true

Language ocl