Policy definition in application-domain-related classes

The definition of classes in an object oriented system is generally specified in terms of attributes and methods since they are represented in programming languages using these constructs. However, there is other information pertinent to application domain related objects (known as policies) that are embedded in methods. Since policies are complex statements that cannot be easily represented in terms of attributes or directly translated into method definition, they are usually realized by a combination of attribute and method implementation. Also, policies are highly volatile elements easily affected by changes in the business environment. One approach as proposed in the paper is to raise the level of representation of policies in class definitions. The purpose is to make policies more distinguishable from the rest of the class definition so that any maintenance effort in accommodating changes in policy definition can be reduced. The paper discusses how policies can be defined in a class definition, the advantages of the proposed approach, and how the proposed class definition can be implemented. An example from the library domain is used to illustrate the class definition approach discussed.