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Chapter 4. The GOPPRR Meta Meta Model – An Extension of GOPRR
meta model. Neither, the proper definition of the static semantics is included in the original
GOPRR syntax description formalism.
A possible solution to these problems could be the extension of the already existing meta
model for the syntax definition. The fact that it does not provide possibilities to define syntax
for the graphical containment of objects opposed this option. Graphical containment means
that the graphical representation of an object o 1 consisting of a set of points P 1 graphically
contains another object o 2 if P 2 ⊆ P 1 . This modelling mechanism can also provide good
abstraction possibilities that should not be ignored. The additional integration of ports and
graphical containment in the original GOPRR syntax description meta model does not seem
very promising because a direct mapping of these meta meta model elements to model elements
is not possible, as it is done for the other GOPRR elements.
Thus, to use all GOPRR features and elements for dependable software, a new syntax
description formalism has to be developed that ideally can be defined as meta model in
GOPRR itself. The formalisms for defining the concrete syntax and static semantics are
introduced in the following sections. Furthermore, an abstract syntax model as C++ structure
and its intermediate representation as XML are presented because the abstract syntax is needed
for the generation process and the definition of the static semantics. Additionally, a possible
transformation from the new GOPPRR meta meta model to MOF can be found in Appendix A.
4.1. Concrete Syntax Description Formalism
The name for the new meta meta model was chosen as Graph, Objects, Properties, Ports,
Roles, and Relationships (GOPPRR) to emphasise the extension about ports. If the term
GOPPRR is used as meta meta model, it refers to the GOPRR meta meta model with the
GOPPRR extensions for the syntax definition, the new abstract syntax model, and the new
definition formalism for static semantics.
In general, the GOPPRR concrete syntax description formalism provides three different
graph types:
1. graph bindings syntax graph
2. sub-graph syntax graph
3. type property graph
Graph Bindings The syntax graph for graph bindings specifies how object types in a certain
graph type can be connected. Figure 4.1 shows the elements of such a graph. The root node of
a graph binding represents the graph type under consideration. Relationship and role types
are child nodes of the graph type. Object types can be children of role or of port types, which
are on the intermediate level between role and object types while the last possibility is an
extension compared to the original GOPRR syntax description formalism. Another important
addition is the definition of graphical inclusions. This means in other words that the graphical
placement of an object within the graphical representation of another one can be used for the
syntax definition. This graphical inclusion for a certain object type is a child node of the graph
type node, and the child nodes are the possible included object types.
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