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

Silverston c03.tex V2 - 11/21/2008 2:59am Page 107

Level 3 Contextual Role Pattern 107

Some enterprises may like or need the semantic rigor of forcing a

new contextual role to be linked to a declarative role.Inotherwords,

some enterprises may say that every specific contextual role must be

supported by an enterprise-wide role (declarative role). One reason for

doing this is to have a more consistent process for adding roles, which

could include always setting up the role first (adding the declarative

role) before using it (adding the contextual role).

Synopsis

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

enterprises to model the different contextual roles that a party may play. The

significance of this pattern lies in the fact the PARTY is directly related

to the contextual roles for another entity such as a PROJECT, ORDER,

or SHIPMENT. This allows any PARTY to play a role in another entity

such as a business transaction or activity without having to be specifically

declared as a declarative role. This approach may suit enterprises that don’t

subscribe to the PARTY ROLE approach, or it may provide an alternative that

allows contextual roles to be related to either a PARTY or a PARTY ROLE,

depending on the circumstances.”

Specific business rules also are easily implemented in this pattern, such as

allowing only a PERSON to be a PROJECT WORKER, or that a PROJECT can

be led by only ...