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

404 Conclusions and Future Work
13.1 Conclusions
This combined thesis establishes the base of the method Software/Hardware Engineering
(SHE). This method incorporates a framework for design activities, and a formal
description language called POOSL (Parallel Object-Oriented Specification Language).
SHE is a system level method for co-specification and design of distributed reactive
hardware/software systems. This method guides analysis, specification and design
activities. The application area is the specification and design of complex systems that
must be partitioned into in hardware and/or software implementations. Examples of
such systems are tele/data communication networks and switches, industrial control
systems, embedded systems and electronic consumer products. There is a typical combination
of carefully designed key features that distinguishes our method from other
ones. These features are:
From Informal Analysis to Formal Specification. Starting from informal object-oriented
analysis and architecture design, SHE produces rigorous behaviour and architecture
descriptions. The result of the use of the method is a formal executable
model and accompanying documents. Requirements that cannot be formalised
are described in a requirements catalogue. The executable model is described
in the formal specification language POOSL. POOSL has a formal mathematical
semantics. In contrast to informal methods, SHE therefore has the potential for
simulation, formal verification, design structure transformation, and automatic
translation for implementation.
View-Oriented Development. SHE supports the simultaneous evolutionary development
of several views, each focusing on particular system aspects. Important
views are behavioural views, architectural views and conceptual views. Abstractions
of these views are combined in an explicit unified formal model described
in POOSL. Behaviour-preserving transformations are offered to keep behavioural
views and architectural views consistent.
Instance-Oriented Approach. Most object-oriented methods use conceptual views.
These are built from class diagrams. Behavioural views in SHE are described by the
visualisation of collaborating instances, such as objects and clusters. A behavioural
view consists of process objects that perform complex interactions using message
passing. The instance-oriented approach visualises process objects that model
autonomous concurrent entities. Data objects are contained in process objects and
model dynamic data structures. Architectural views show a structure of modules
and channels. Architecture and implementation structure of a system is formalised
by representing modules as instances of clusters that group collaborating process
objects.
Scenarios. Behaviour views are build from scenarios. Separate scenarios are used
to model different discipline-oriented and function-oriented views. Scenarios are
developed using an event/response approach derived from Structured Analysis
and Structured Design Methods, combined with our instance-oriented approach.
Events represented by messages evoke responses. Methods model response behaviour.
Methods in process objects handle sequences of messages, mutually call