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

Silverston c07.tex V2 - 11/20/2008 5:44pm Page 403

Summary of Patterns 403

modeling it as an attribute of an associative entity between a party and the

contact mechanism (except for the level 1 pattern, which does not have an

associative entity). This allows the general number to be shared (for example,

many people may have the number ‘‘1 917 555 2100’’ for the company) and

the telephone extension to be specific to that party and contact mechanism.

In the level 1 pattern, the telephone extension can be maintained as an

attribute of a PARTY. In the level 2 pattern it can be maintained as an attribute

of the PARTY TELECOMMUNCATIONS NUMBER. In the level 3 pattern it

can be maintained as an attribute of the PARTY CONTACT MECHANISM

and in the level 4 pattern, it can be maintained as an attribute of the CONTACT

MECHANISM APPLICATION. There is one wrinkle in that if multiple people

share an extension, there could be some redundancy in having to maintain that

same extension for each person. Therefore, this can be maintained as another

attribute of the telecommunications number or another solution could be to

have a TELEPHONE EXTENSION entity tied to the association entity for a

party and a contact mechanism; however, this is usually overkill for most

enterprises.

Synopsis

This section covered possible ways to model four additional aspects of con-

tact mechanism data: non-solicitation, instructions, directions, ...