SOFTWARE DESIGN METHODS AND REPRESENTATIONS - Software Design for Six-Sigma: A Roadmap for Excellence - page 88

architecture is the integration of software development methodologies and models
and is used to aid in managing the complex nature of software development.
One type of approach in particular that may be gaining some popularity recently
is model-driven architecture. Model-driven architecture provides a set of guidelines
for the structuring of specifications expressed as models. Model-driven architecture
was launched by the Object Management Group (OMG) in 2001. 22
Four general principles underlie model-driven architecture. First, models are ex-
pressed in a well-defined notation and are important for understanding systems for
enterprise-scale solutions. 23 Second, the building of systems can be organized around
a set of models by imposing a series of transformations between models. Third, de-
scribing models in a set of meta-models facilitates meaningful integration and trans-
formation among models, which is the basis for automation through tools. Finally,
acceptance and broad adoption of this model-based approach requires industry stan-
dards to provide openness to consumers and to foster competition among vendors.
Indeed, model-driven architecture encourages the efficient use of system models in
software development and supports the reuse of best practices when creating families
of systems.

4.5 SYSTEM-LEVEL DESIGN APPROACHES

There are three traditional main system-level design approaches: hardware/software
codesign, platform-based design, and component-based design (Cai, 2004).

Hardware/Software codesign (also referred to system synthesis) is a top-down
approach. It starts with system behavior and generates the architecture from
the behavior. It is performed by gradually adding implementation details to the
design.
Platform-based design: Rather than generating the architecture from the sys-
tem behavior as in codesign, platform-based design maps the system behavior
to predefined system architecture. Examples of platform-based design are in
(Keutzer et al., 2000), (Martin & Salefski, 1998) .
Component-based design: It is a bottom-up approach. To produce the predefined
platform, it assembles existing heterogeneous components by inserting wrappers
between these components. An example of component-based design is described
in Cesario et al., (2002).

In addition, in this topic, we are adding axiomatic design 24 as a new representation
method. It is presented in Chapter 13.

22 http://en.wikipedia.org/wiki/Model-driven architecture.
23 http://www.ibm.com/developerworks/rational/library/3100.html.
24 Axiomatic design is a systems design methodology using matrix methods to analyze systematically the
transformation of customer needs into functional requirements, design parameters, and process variables
(El-Haik, 2005).