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

Silverston c04.tex V2 - 11/21/2008 3:02am Page 180

180 Chapter 4 ■ Hierarchies, Aggregations, and Peer-to-Peer Relationships

prerequisite work effort has been completed, or the application may

make sure that any calculations d o not include numbers for work efforts

that have been ‘‘excluded’’ via work effort association rules.

There is a need to capture the rules of an enterprise to better under-

stand the enterprise. If an enterprise is very rule-driven when managing

data, this pattern will support its ethos.

What Are the Weaknesses of the Pattern?

The weaknesses of this p attern are as follows:

This pattern is a more generalized form of modeling. With general-

ization comes confusion on how to use this structure. Care needs to be

taken to ensure that the structure is well understood by all stake holders.

This is quite a new concept and takes time to gain buy-in with many

enterprises. Many enterprises will consider this overkill. However, we

have implemented this pattern in rule-driven enterprises with great suc-

cess.

NOTE

This pattern has similar strengths and weaknesses to those of the

previous pattern. This past section only focused on the strengths and weaknesses

of adding WORK EFFORT ASSOCIATION RULE to the pattern.

Synopsis

In this section you saw another way to view the relationships that exist

between the different associations in a recursive relationship. You saw how

we defined the behavior ...