Information Technology Reference
In-Depth Information
stream. In DeSCAS, OWL ontologies are used for the formal representation
of such domain knowledge. OWL (Web Ontology Language) is a widely-used
and open standard for describing ontologies and has been specified by the
W3C
3
. The benefit and advantage of using OWL is its formal semantics which
supports the application of a so-called
reasoner
. A reasoner is not only able
to verify the consistency of the concepts modeled within an OWL ontology
but also to perform logical deduction in order to automate analysis methods.
Domain standards such as ISO 26262 and the RESPONSE 3
Code of
Practice
supply domain terminology as in a glossary, reference process models
and meta-models, as well as process- and product-related requirements. In
order to show compliance of the development process to standards relevant
for the system to be developed, these standards shall be formalized as done
in DeSCAS with the committee draft of ISO 26262. The formalization of each
standard involves modeling on the meta-model level and the model level:
-
Derive an ontology from the standard (meta-model level):
This ontology
model is often related to the document structure of the standard. Con-
cerning the committee draft of ISO 26262, about 60 meta-model concepts
had to be modeled.
-
Model actual requirements and relations (model level):
This does not nec-
essarily mean that the requirements need to be presented in a formal way
(e.g. using formal languages) but rather documenting the relations and
connections between several requirements and the relevant methods and
measures, respectively, in a formalized way. The ontology of the commit-
tee draft of ISO 26262 exhibits up to 1000 instances of model concepts.
2.3
Semantic Reasoning
Fig. 1. Interweaving and reasoning within the DeSCAS methodology
Interweaving of models on the basis of formalized domain knowledge can
be structured as follows, with Fig. 1 locating the steps within the respective
development streams [2]:
3
OWL - http://www.w3.org/TR/owl-ref/
