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4.1. Concrete Syntax Description Formalism
GraphType
RelationshipType1
RelationShipType2
RoleType11
1...1
RoleType12
1...*
RoleType21
1...*
RoleType22
0...1
RoleType23
1...*
PortType1
0...1
PortType2
1...*
ObjectTypeWithPorts11
1...1
ObjectTypeWithPorts12
1...*
ObjectType21
1...*
ObjectType22
0...*
ObjectType23
1...1
ObjectType21
0...*
ObjectTypeWithPorts11
0...*
ObjectTypeWithoutBindings
1...1
Figure 4.1.: Example of a meta model graph bindings definition
Role, port, and object type nodes have a cardinality written below the name label, which
have different meanings for different nodes. The cardinality of roles define how often they can
or have to be used in a certain relationship instance. For object and port types, the cardinality
refers to their possible connections under the corresponding role type. The cardinality of
graphical inclusion nodes refers to their occurrence in the corresponding graph type.
The multiple, graphical occurrence of a certain relationship type node under the same graph
type node means a disjunction of the below defined role, port, and object types. In other
words, those relationship type definitions can be used alternatively. Also, other elements than
relationships in a certain graph (roles, ports, and objects) can be used multiple times since
their cardinality may differ for different parent nodes.
Sub-Graphs The syntax graph for sub-graphs and occurrences defines the interconnection
between different graph types and the occurrence of object types in a certain graph type. An
example is given in Figure 4.2. As in the definition for bindings, the root node is always
a graph type. Child nodes are object, relationship, and role types. As stated above, only
object types can have decompositions, but all three types may have explosions. To define more
complex, potentially recursive, graph interconnections, sub-graph nodes can have again object,
relationship, and role type child nodes.
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