Page 231 - DCAP405_SOFTWARE_ENGINEERING

Software Engineering

Notes Requirements Specification

For most engineering professions, the term “specification” refers to the assignment of numerical
values or limits to a product’s design goals. Typical physical systems have a relatively small
number of such values. Typical software has a large number of requirements, and the emphasis
is shared between performing the numerical quantification and managing the complexity of
interaction among the large number of requirements. So, in software engineering jargon,
“software requirements specification” typically refers to the production of a document, or its
electronic equivalent, which can be systematically reviewed, evaluated, and approved.
For complex systems, particularly those involving substantial non-software components, as
many as three different types of documents are produced: system definition, system
requirements, and software requirements. For simple software products, only the third of these
is required.

Figure 13.3: Types of Requirement Document

Specify the requirements
and read them to check
System customers that they meet their needs.
They specify changes to
the requirements.

Use the requirements
document to plan a bid
Managers for the system and to
plan the system
development process

Use the requirements to
System engineers
understand what system
is to be developed

Use the requirements
System test engineers to develop validation
tests for the system

Use the requirements to
System help understand the system
maintenance engineers and the relationships
between its parts

There are some approaches to requirements specification:
Natural language
Structured natural language

Design description language
Requirements specification language

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