Software Engineering

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CHAPTER 11 
Functional Analysis and Allocation Practice
controlling function. The functional interface represents the mechanism for achiev-
ing encapsulation, the object-oriented approach to information hiding.
The passing of data between a software function and an external application or 
system represents a software interface that is specified by a software interface spec-
ification. Therefore, the functional architecture must identify these external applica-
tions or systems outside the boundary of the functional architecture to reflect the 
software interface. Software interfaces represent a multiparty contract that must be 
conformed to as it pertains to the definition of the interface design and implementa-
tion characteristics.
Global data items represent data that is accessible to any function. This type 
of data item does not represent a data flow due to the “global” availability of the 
parametric value. The global data value is available to all functions within the soft-
ware architecture. Local data items represent variable or constant parameters that 
are declared internal to a function and not accessible to other functions. Therefore, 
access to local data items does not represent a data flow.
The data flow diagram has been used to represent a data-centric view of the 
software data processing transactions. It represents the data items as the pri-
mary elements of interests and the functions as the connectors or transformation 
agents between data item states. The behavior model combines the functional flow 
sequences with the data flows to provide a more general and complete representation 
of the software data processing scenarios. A software data dictionary (nomenclature 
document) must be produced to ensure that each data item is uniquely identified and 
their characterization is available to all members of the software development team.