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CHAPTER 12 ANALYSIS MODELING 303

FIGURE 12.2 Objects: Attributes: Relationships:
Data objects,
attributes and Name
relationships Address
Age
Driver's license
Number

owns

Make
Model
ID number
Body type
Color

Data objects. A data object is a representation of almost any composite informa-
tion that must be understood by software. By composite information, we mean some-
thing that has a number of different properties or attributes. Therefore, width (a single
value) would not be a valid data object, but dimensions (incorporating height, width,
and depth) could be defined as an object.
A data object is a
representation of any A data object can be an external entity (e.g., anything that produces or consumes
composite information information), a thing (e.g., a report or a display), an occurrence (e.g., a telephone call)
that is processed by or event (e.g., an alarm), a role (e.g., salesperson), an organizational unit (e.g., account-
computer software.
ing department), a place (e.g., a warehouse), or a structure (e.g., a file). For example,
a person or a car (Figure 12.2) can be viewed as a data object in the sense that either
can be defined in terms of a set of attributes. The data object description incorporates
the data object and all of its attributes.
Data objects (represented in bold) are related to one another. For example, per-
son can own car, where the relationship own connotes a specific "connection” between
WebRef
person and car. The relationships are always defined by the context of the problem
Useful information on
data modeling can be that is being analyzed.
found at A data object encapsulates data only—there is no reference within a data object
www.datamodel.org 1
to operations that act on the data. Therefore, the data object can be represented as
a table as shown in Figure 12.3. The headings in the table reflect attributes of the
object. In this case, a car is defined in terms of make, model, ID number, body type,
color and owner. The body of the table represents specific instances of the data object.
For example, a Chevy Corvette is an instance of the data object car.

1 This distinction separates the data object from the class or object defined as part of the object-ori-
ented paradigm discussed in Part Four of this book.