Software Engineering

180
CHAPTER 10 
Formulating the Functional Architecture
software requirements describe the software product from an operational or 
business process perspective, the identification of primary functions may not 
correspond to or coincide with the requirements. This may be reflective of the 
terminology used to describe the operational or business process. The software 
requirements must be translated into software functions that reflect semantics 
associated with the appropriate software domain. A software domain reflects a 
field of study that defines a set of common requirements, terminology, and func-
tionality for any software program constructed to solve a problem in that field.
2. 
Decompose primary functions.
 The primary functions can be assumed to be 
complex since they have been derived from the operational or business process 
descriptions. Each complex function represents a software task of which the 
solution is too extensive or challenging to comprehend. Functional decom-
position involves reducing complexity by investigating the problem space to 
improve the understanding from which a design solution can be conceived.
●
 
Functional decomposition.
 Functional decomposition identifies the proce-
dural operations by which a complex function will be performed. In most 
cases, there are multiple approaches by which a complex function can be 
accomplished, and each design approach or alternative will exhibit different 
performance and architectural quality characteristics.
●
 
Model functional behaviors.
 Construct a model of how the function behaves 
by identifying the functional sequences, data items, and control mechanism 
necessary to perform the source function. The performance characteristics 
and resource utilization criteria specified for the source function must be 
budgeted or allocated among subfunctions.
●
 
Evaluate alternative approaches.
 Every functional decomposition or behav-
ioral model involves design alternatives. Contending alternatives should 
utilize the software analysis activity to evaluate, prioritize, and select a pre-
ferred solution. Each solution should be assessed to understand its effective-
ness, suitability, and risks in terms of satisfying the specified performance 
requirements and desired software quality characteristics.
●
 
Identify implied behaviors.
 Functional solutions should be evaluated to iden-
tify inferred, complementary, or supplementary behaviors that enhance the 
data processing thoroughness. It should be assumed that the specification is 
incomplete and has converged on a suitable expression of the data process-
ing actions. The functional solution must be meticulously evaluated to iden-
tify behaviors needed to contend with every possible situation that may arise 
during data processing.
●
 
Optimize the functional solution.
 The functional solution should be evaluated 
to identify aspects that have the largest influence on software performance 
and resource utilization. Important aspects of the initial functional solution 
should be refined to increase the effectiveness of the solution, such as data 
integrity, possible causes of failure conditions, input/output data item defini-
tions, and the precision of data transformation algorithms.

---