Specification of Reactive Hardware/Software Systems - Electronic ...

132 Concepts for the Integration of Specification and Design
Initial
Requirements
Maintenance
Reliability
Standards
Timing
Test
Conceptual
(Object classes)
Manufacturing
Packaging
Other views..
Unified
Behaviour Architecture
Model
Legislation
Figure 5.8: View-Oriented Refinement
appear in the specification document. However, they are not integrated in the Unified
Model. Another part of the safety view will lead to refinement of Behaviour and/or
Architecture. Figure 5.8 visualises the growth of both these fields. Behaviour and
architecture refinement will be formalised into a Unified Model. We define such a view
based refinement as view-oriented refinement. Notice that this form can lead to horizontal
and (de)composition refinement of the behaviour model. The purpose will always be the
same. Firstly a complete model must be found, which means with all necessary objects.
Secondly a hierarchical structure must be found. This structure must be adequate for
the problem domain and consistent with all views. In general, both steps add details at
various levels of abstraction. Objects may be added at various levels. Clustering affects
the levelling itself.
View-oriented refinement leads to finding new objects and/or new messages between
collaborating objects. For an optimal communication with domain experts we defined an
operating procedure that enables highlighting of the appropriate information. Specific
views will be represented in the form of Object Instance Models. In the next chapter,
Section 6.5, we introduce scenarios as a view specific abstraction of collaborating objects.
Safety