Schaum's Outline Series

Requirements
8.1 Introduction
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The goal of the requirements phase is to elicit the requirements from the user. This
is usually achieved by the development of diagrams and the requirement specification
after discussions with the user. The user then reviews the diagrams and
specification to determine if the software developer has understood the requirements.
Thus, it is essential that the diagrams and specifications communicate back
to the user the essential aspects required of the software to be produced.
The following sections describe the diagrams and requirement specification that
are useful in achieving this communication.
8.2 Object Model
The basic approach in an object-oriented (OO) methodology is to develop an
object model (see Section 2.4) that describes that subset of the real world that is
the problem domain. The purpose is modeling the problem domain and not
designing an implementation. Thus, entities that are essential to understanding
the problem will be included even if they are not going to be included in the
solution. The attributes and methods included in the object model will also be
those needed for understanding the problem and not those that will just be important
for the solution.
The following are rules for object models for requirements:
1. All real-world entities that are important to understanding the problem
domain must be included.
2. All methods and attributes that are important to understanding the
problem domain must be included.
3. Objects, attributes, and methods that are only significant for the implementation
should not be included.
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