Domain + Control + Policy  Reusability

Bindu Rama Rao
Integrated Solutions
brr@mcs.com

and

Lizette Velazquez
Lucent Technologies
lizette.velazquez@lucent.com
708-979-6695

Lizette Velazquez
Rm. IH 6S-213
2000 N. Naperville Rd 
Naperville, IL 60566

Abstract

Reusability of objects within the same product is possible if the
domain objects have no knowledge of the activities in which they are
employed. This requires the separation of activity-specific
information from objects in the domain. As a partial solution, control
objects are recommended [Jacobson, 95] for encapsulating control type
information that are associated with any activity. This scheme works
fine for modeling a product for a specific customer in terms of
reusable domain objects and activity-specific control
objects. However, when similar products for multiple customers are to
be modeled, the customer specific information are unfortunately
captured in control objects or domain objects or both. Hence, the
reusability of objects is often compromised. A complete solution would
require the use of policy objects along with control objects. This
paper presents a set of three patterns, Plurality of Customers and
Features, Control Information Decoupler, and Policy Decoupler. The
first of these employs the other two.