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Chapter 9. openETCS Generator Application
CGOPPRRTransformer to be able to provide a GOPPRR C++ abstract syntax model to
the generator classes. The m_ConstraintChecker composition is used to check the GOPPRR
C++ abstract syntax model validity according to the meta model constraints or rather static
semantics.
DSM For general domain-specific modelling issues, this package provides a composite design
pattern for transformer and abstract syntax model classes. Generally, transformer classes
convert an intermediate model from an XML file to an abstract syntax tree. Therefore, for
each one a base class (CSyntaxTransformer and CSyntaxTree) is defined, which corresponds
to the component participant [32, p. 165] of the design pattern. CGOPPRRTransformer and
CGOPPRRSyntaxTree are the concrete leafs [32, p. 165] for the GOPPRR meta meta model.
As already explained above, the integration of this pattern is mainly relevant for possible
extensions by further abstract syntax models in further work.
GOPPRR The detailed structure of the GOPPRR C++ abstract syntax model was already
introduced and discussed in Section 4.2 and sketched in Figure 4.4. New in this package is the
CConstraintChecker class for checking a certain CProject object for a set of constraints. Due
to the definition of GOPPRR and its C++ abstract syntax model, also the constraint checker
is completely independent from the meta model and can be easily implemented in one class.
xmlpp In the UML model, the xmlpp package only represents the external libxml++ library,
which is used for the parsing of XML files.
9.4. Deployment Design
The differentiation by the three MDA model categories, as in Section 8.5, is not necessary for
the generator application because it is not part of the model. Neither, the generator has to be
executed in a different execution environment, nor an IPC has to be established.
How the different packages are combined or rather deployed together to build an executable
binary is of special interest for the generator application development. Thus, the deployment
of the GOPPRR and DSM package is introduced first and at last the GEN package, which
combines all components.
GOPPRR Corresponding to its definition in Section 4.2, the GOPPRR C++ abstract syntax
model is independent from the meta model and accordingly heavily reusable. Hence, its
deployment as a library [77] seems to be the most appropriate. The deployment of the
libGOPPRR is sketched in Figure 9.3. The artefacts hold the corresponding classes with the
“C” prefix and all manifest the libGOPPRR component. The ExceptionTypes artefact holds
the exception classes used for the abstraction methods for easier accessing be graph bindings
in an abstract syntax model (see Section 4.2). The libGOPPRR component provides all classes
to other components, which accordingly have to import or rather link against the libGOPPRR
library. Figure 9.4 shows the corresponding component diagram.
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