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

Silverston c02.tex V2 - 11/21/2008 2:58am Page 65

Summary of Patterns 65

you obscure the fact that some of the roles are only for PEOPLE and

some of the roles are just for ORGANIZATIONS. At first glance, this pat-

tern seems to imply that all roles may be related to any type of PARTY.

However, there are other ways to show which roles are applicable to

people, organizations, or parties.

If parties do not ever play more than one role, then the advantage

of reducing redundancy may not be a factor. Thus, if there are not

situations where people or organizations play more than one role, the

application of this pattern may be overkill. However, in our experience,

people and organizations will often be involved in more than one role.

Synopsis

In this section we described a flexible pattern that can be used by many

enterprises to describe the different declarative roles that are applicable.

This pattern is significant because it captures all of the common attributes and

relationships that declarative roles have as part of the PARTY ROLE supertype

and it provides a ROLE TYPE entity to maintain information on role types. By

doing this, the enterprise makes it easier to add and change declarative roles.

The PARTY ROLE supertype helps by providing a convenient way to capture

all the different declarative roles that an enterprise is interested in with a

single structure, and it allows this supertype to be related ...