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Conclusion and Outlook
This chapter provides the overall conclusion of this dissertation and proposes possible future
work for related research.
The chapters in the Background part (Part I) provided several concepts that are relevant for
the development of OSS/FLOSS for safety-critical train control applications. It was identified
that the current and typical principles of software development of OSS / FLOSS are not
sufficient for the certification for applicable safety standards. Thus, the principles of DSM
were discussed by examples of several state-of-the-art meta meta models. Additionally, an own
extension of the existing GOPRR meta meta model was introduced, which complies with all
requirements for defining a completely formal meta model. Besides a tree- and graph-based
graphical formalism for defining the concrete syntax of a meta model, also the definition of an
abstract syntax model and the integration of OCL for defining constraints as static semantics
were developed.
Part Dependability (Part II) dealt with issues related to safety and security in connection
with the idea of developing safety-critical software as OSS / FLOSS. Applicable safety standards
for the railway domain were illuminated and a possible concept developed to integrate the
usage of DSM in the software life cycles, which is defined by these standards. This also included
the new integration of V&V based on model properties. Furthermore, the new term open
model software was raised, which, in contrast to the the traditional open source software,
refers to a MDA developed under the principles and licenses of OSS / FLOSS. New security
problems caused by the usage of open model software were identified and discussed. The usage
of hardware virtualisation, in contrast to traditional operating system strategies, to oppose
those security risks was investigated and elaborated as possible strategy to be used together
with open model software.
To proof the correctness and applicability of the developed concepts, part openETCS Case
Study (Part III) introduced a completely developed case study for ETCS. This included all
required instances for a DSL: Starting from the meta model as formal specification language, to
the concrete formal model of a sub-subset of the ETCS SRS, and finally down to the generated
source code. Furthermore, all new generators between those instances or rather artefacts were
developed and discussed. The meta model description was identified as the most crucial part
of the development because any errors made in the definition of the concrete syntax or the
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