The Data Model Resource Book, Volume 3: Universal Patterns for Data Modeling

Silverston c06.tex V2 - 11/21/2008 3:09am Page 261

Level 3 Status Pattern 261

This pattern is not as effective as the Level 1 Status Pattern at graphi-

cally illustrating the scope of the different statuses that an entity may

have. The statuses are captured as instances of the STATUS TYPE and

not specifically as attributes. Therefore, they are not visible in the dia-

gram or as easy to understand for nontechnical audiences.

Synopsis

In this section you examined how Level 2 Status Pattern, Current Status, meets

the specific needs that some enterprises have.

First, this pattern captures all the different statuses that an entity has

by generalizing all of the different types of status into a STATUS TYPE

(and alternatively may include various subtypes) as seen in Figure 6-4 and

implemented in Figure 6-5.

Because the status types are captured in the STATUS TYPE entity and not

as specific attributes, the pattern accommodates change more easily because if

a new status type is needed, you can simply add a new instance to STATUS

TYPE and need not change the model.

This pattern has a somewhat narrow focus, to meet the specific need of only

capturing the current status of an entity. However, in one aspect, it provides

more flexibility than the Level 1 Pattern because it introduces the STATUS

TYPE for the first time in this chapter. This allows you to add new instances of

statuses when they are discovered.

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