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

Silverston c07.tex V2 - 11/20/2008 5:44pm Page 329

Level 2 Contact Mechanism Pattern 329

Both CONTACT MECHANISM USAGE TYPE and CONTACT

MECHANISM PURPOSE are related to the entities ENTITY CONTACT

MECHANISM 1 and ENTITY CONTACT MECHANISM 2. Modeling the

purpose and the usage in addition to the CONTACT MECHANISM TYPE pro-

vides flexible combinations for maintaining contact mechanisms. For example,

imagine a person who works from home. This person (a PARTY) may have

a t elecommunications number of ‘‘Fax number’’ (CONTACT MECHANISM

TYPE) that is used for ‘‘Business’’ (CONTACT MECHANISM USAGE TYPE)

for the purpose of ‘‘Technical support’’ (CONTACT MECHANISM PURPOSE

TYPE). This same telecommunications number may be used as a ‘‘Telephone

number’’ (CONTACT MECHANISM TYPE) by that person’s husband for per-

sonal use (CONTACT MECHANISM USAGE TYPE) with no purpose. Usage

and purpose are relevant within the context of the PARTY’s relationship to the

CONTACT MECHANISM.

Figure 7-4 and Figure 7-5 further illustrate how to employ this pattern. For

illustration, we can build upon the scenario d escribed in the Level 1 Contact

Mechanism Pattern section of the chapter. Initially, ABC Building Corporation

wished to buy an off-the-shelf contact management software to manage its

contact mechanism. They used Figure 7-2, based on the Level 1 Contact Mech-

anism Pattern, to evaluate third-party vendor contact management