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3.1. Meta Meta Models
additional syntax for the meta meta model has to be investigated for understanding it. In
other words, UML is the meta model and MOF the meta meta model. This grants a high
duality between software design and meta model.
MOF can be generally divided in EMOF (Essential MOF) [60], which specifies the essential
elements of MOF, and CMOF (Complete MOF) [60], which holds all available MOF elements.
Due to the complexity of CMOF, only EMOF is explained here, beginning with all general
EMOF types in Figure 3.6.
Element
NamedElement
name : String
annotatedElement
0...*
ownedComment
0...*
TypedElement
type
0...1
Type
Comment
body : String
Figure 3.6.: EMOF types
Element is the most general and abstract base class for any element in MOF. It holds a set of
comments (ownedComment).
NamedElement is the abstract base class for all elements with an additional, internal name.
Hence, it has the attribute name.
Type is the abstract super class for all classes and data types.
TypedElement is the abstract base class for all typified elements.
Comment is used for commenting any element. Thus, it provides the attribute body, in which
the literal comment is stored. It has an aggregation to its possessing element (element).
All classes marked with are abstract classes [79], which generally means they
cannot be instantiated directly, only by generalisation / inheritance [62, 79].
Furthermore, EMOF provides the possibility of modelling data types. Figure 3.7 introduces
the relations between the built-in data types. New elements are:
DataType is the general class for all data types.
PrimitiveType is a class for all primitive data types.
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