Software Engineering

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CHAPTER 18 
Software Architecture Definition
into a complete functional hierarchy. It also derives the preliminary physical archi-
tecture that defines the conceptual components of the structural configuration. 
The second stage, detailed architecture definition, finalizes the physical architecture 
by establishing the specifications for structural units and components while estab-
lishing the software integration strategy. During the software architecture definition 
stage, the computing environment definition should be established to devise a uni-
fied software product architecture.
During the preliminary stage of architectural definition, the top-level functions 
are analyzed and decomposed into a complete functional hierarchy of components 
and units. There is no set number of levels for this decomposition. However, the 
decomposition should continue until the functional solution is well understood, 
complete, and noncomplex. When a functional element is recognized to represent 
an uncomplicated data processing action, then no further decomposition is neces-
sary. Uncomplicated elements should be labeled functional units, which represent 
the foundational piece of the architecture. Functional unit specifications should be 
prepared to reflect the functional characteristics established by the behavior model. 
The physical architecture definition is instigated by conceiving a conceptual struc-
tural solution. This structural solution represents an arrangement of conceptual 
components that coalesce principal data processing functionality that is ultimately 
provided by a set of underlying structural elements. This stage of development con-
cludes with the preliminary design review (PDR). The PDR is intended to demon-
strate that the functional decomposition and behavioral models are complete and in 
compliance with the software requirements.
During the detailed architecture definition stage, the lowest-level structural 
units must be conceived by aligning and grouping functional units around coherent