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CHAPTER

SYSTEM ENGINEERING
10

KEY lmost 500 years ago, Machiavelli said: "there is nothing more difficult
CONCEPTS to take in hand, more perilous to conduct or more uncertain in its suc-
application Acess, than to take the lead in the introduction of a new order of things."
architecture . . . 253
During the past 50 years, computer-based systems have introduced a new order.
business process Although technology has made great strides since Machiavelli spoke, his words
engineering. . . . . 251
continue to ring true.
data Software engineering occurs as a consequence of a process called system
architecture . . . . 252
engineering. Instead of concentrating solely on software, system engineering
hierarchy. . . . . . . 247
focuses on a variety of elements, analyzing, designing, and organizing those
product elements into a system that can be a product, a service, or a technology for the
engineering. . . . . 254
transformation of information or control.
requirements The system engineering process is called business process engineering when
elicitation . . . . . . 256
the context of the engineering work focuses on a business enterprise. When a
requirements product (in this context, a product includes everything from a wireless tele-
engineering. . . . . 256
phone to an air traffic control system) is to be built, the process is called prod-
system
elements. . . . . . . 246 uct engineering.
Both business process engineering and product engineering attempt to bring
system
modeling. . . . . . . 262 order to the development of computer-based systems. Although each is applied
in a different application domain, both strive to put software into context. That
validation. . . . . . 260

QUICK What is it? Before software can est” is the system, and the trees are the technol-
LOOK be engineered, the ”system” in ogy elements (including software) that are
which it resides must be under- required to realize the system. If you rush to build
stood. To accomplish this, the overall objective of technology elements before you understand the
the system must be determined; the role of hard- system, you’ll undoubtedly make mistakes that
ware, software, people, database, procedures, will disappoint your customer. Before you worry
and other system elements must be identified; and about the trees, understand the forest.
operational requirements must be elicited, ana- What are the steps? Objectives and more detailed
lyzed, specified, modeled, validated, and man- operational requirements are identified by elicit-
aged. These activities are the foundation of system ing information from the customer; requirements
engineering. are analyzed to assess their clarity, completeness,
Who does it? A system engineer works to under- and consistency; a specification, often incorpo-
stand system requirements by working with the rating a system model, is created and then vali-
customer, future users, and other stakeholders. dated by both practitioners and customers. Finally,
Why is it important? There’s an old saying: “You can’t system requirements are managed to ensure that
see the forest for the trees.” In this context, the ”for- changes are properly controlled.

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