E (informative) UML notions used within MAF
E.1 Introduction
MAF complies with the specifications and modeling principles of UML as
defined by OMG [32]. UML is well defined and broadly used in the
industry. MAF uses a subset of UML that is relevant for linguistic
description.
The following notions are used:
-
The notion of class
- The notion of relationship
- The notion of instance
- The notion of package
E.2 The notion of class
A class is a named descriptor for a set of objects that share the same
attribute s and relationships. Classes are described within a class
model.
E.3 The notion of attribute
An attribute is the description of a named element of a specified type
in a class; each object of a class separately holds a value of the
type.
E.4 The notion of relationship
A relation is a connection between classes. This includes association
and generalization. Relations are described within a class model.
E.5 The notion of association
An association is a relationship between two specified classes that
describes connections among their objects. The extension of the
association is a collection of such links. Associations are the
glue that holds together the model: without associations, there
is only a set of isolated classes. An association holds two ends. Each
end has "a multiplicity" and an ordering qualifier.
The multiplicity is the specification of the range of allowable
cardinality values that a collection may assume. The multiplicity
range is an integer interval with its minimum and maximum values.
An ordering qualifier specifies whether the connection forms a set (an
unordered collection) or a list (an ordered collection).
E.6 The notion of aggregation
An aggregation is a form of association that specifies a whole-part
relationship between an aggregate (a whole) and a constituent part. It
is not permissible for both ends to be aggregates.
E.7 The notion of generalization
A generalization relationship is a directed relationship between two
classes. On e class is called the parent or the super-class, and the
other is called the child or the sub-class. The parent is the
description of a set of objects with common properties over all
children. The child is a description of a subset of those objects that
have the properties of the pa rent but that also have additional
properties peculiar to the child. A parent may have more than on e
child and a child may have more than one parent. Generalization is a
transitive and anti-symmetrical relationship. No directed
generalization cycles are allowed. A child inherits the attributes
and associations of its parent.
E.8 The notion of instance
An instance is an object that conforms to a class. Instances are not
described within a class model but within an instance model (sometimes
called an object model).
E.9 The notion of package
A package is a grouping of classes and relations. Usually there is a
single root package that owns the entire model for a system. A package
may contain nested packages. Packages may have dependencies to other
packages.
E.10 Graphical notations
Each notion has a graphical notation that is precisely defined as
follows: