Software Engineering

32
CHAPTER 2 
Generic Software Development Framework
teams who produced the computer languages and compliers who translate code into 
machine-executable instructions. To discuss the software breakdown it is necessary 
to utilize terms that do not carry superfluous connotations. The terms must indicate 
a relative position within the product hierarchy or structural configuration. This will 
be facilitated by the use of 
component
 and 
unit
. Component infers a part, ingredi-
ent, or constituent forming a part of something larger. More importantly, per the 
Encarta Dictionary
, component is used to define an assembly as “a set of compo-
nents before they are put together to make a finished product.” From this it can be 
inferred that a software component represents an element of the software break-
down structure (SBS) from which the final product is assembled. Component also 
is flexible enough to accommodate its use to represent several layers of assembly, 
as illustrated in 
Figure 2.2
.
This structural concept works well with the exception that it implies a never-
ending hierarchy of components. Therefore, it is necessary to establish a soft-
ware building block that will terminate the hierarchy. For this, the term 
unit
 will 
be used. A software unit represents the basic element or part of a software product 
from which initial software components will be assembled. The 
Encarta Dictionary
 
defines unit as “an individual or discrete part or element into which something can 
be divided, especially for analysis.” Thus, a software unit represents a discrete ele-
ment of the SBS from which a software component can be assembled. 
Figure 2.3
 
depicts an example of a SBS.
Throughout the material presented in this book the terms 
component
 and 
unit
 
will refer to the position or station the software element has relative to the hierar-
chy of software elements. A software unit is the basic building block and does not 
involve any decomposition or further breakdown. A software component represents