From: Gonzalo Génova (firstname.lastname@example.org)
Date: Fri 17 May 2002 - 11:10:07 BST
Simona, Your relation ass' can have a multiplicity only if it is an association, that is, if it is an instance of the metaclass Association; note that Association is a metaclass, not a meta-association. There are many meta-associations in the metamodel, which represent different relationships between model elements, the instances of which are not "associations" in the strict sense, therefore they do not have multiplicity specifications. For example, the metaclass Generalization has two metaassociations with the metaclass GeneralizableElement: child and parent (see Figure 2-6 in the UML Specification). This structure in the metamodel level is used to represent a generalization in the model level, which of course has no multiplicities. There isn't any associations in the model level that correspond to the meta-associations child and parent. The multiplicities in the metamodel mean that a generalization has exactly one parent and one child (it is a binary relationship), and that a GeneralizableElement can participate in several generalizations, as child or as parent. The multiplicities of an association at the model level are represented at the metamodel level by the metaattribute AssociationEnd.multiplicity. You can put any value in a multiplicity specification when you instantiate the metamodel to create a model. I hope I answered your question. Gonzalo -----Mensaje original----- De: Simona Bernardi [mailto:email@example.com] Enviado el: Wednesday, May 15, 2002 5:45 PM Para: firstname.lastname@example.org; email@example.com Asunto: associations defined in a metamodel Hello, I have a question about how associations defined in a UML meta-model are instantiated. What happens to the multiplicities of an association defined between two meta-classes ? For example an association "ass" is defined between two metaclasses A and B, with multiplicity * (not explicitly defined): ass |A| -----> |B| * An instantiated model can be made of a class A' (instance of the metaclass A) and a class B' (instance of B) and relation ass' between A' and B'. Does the multiplicity of ass' have to be a specific number or it can still remain unspecified with "*" ? Thanks, Simona. To remove yourself from this list please mail firstname.lastname@example.org with a message containing the word "unsubscribe".