Alternate Name: Common Business Entities Domain::Policy ABE::Policy Structure ABE::Policy Variable ABE
Category: [a] Class
This is an abstract class for modeling different types of variables that can be used to form a PolicyStatement. The variable specifies an attribute or concept that should either be matched or in some way compared to a value when the condition is evaluated.\n\nThere are three important factors that must be taken into account in the design of variables. The first is that not every combination of a variable and a value creates a meaningful condition. For example, port numbers cannot be negative. Rather, the type of variable in the condition defines the set of matchable value types.\n\nSecond, just because a value has the correct datatype does not mean that it can be meaningfully compared to a variable. To continue the above example, a port of 1,000,000 is meaningless. This is handled in this model by specifying constraints (using OCL) that apply to a particular variable that must be obeyed by any value that it is being compared to. The ExpectedPolicyValuesForVariable association binds a PolicyVariable to a PolicyValue; any constraints that are required in this binding are added to an instance of this association using OCL.\n\nThird, while the DEN-ng model defines a set of useful PolicyVariables, there is a high likelihood that specific applications will need extensions to these variables. This is accommodated through the notion of implicit and explicit PolicyVariable classes.\n
This was created from the Frameworx 16.0 Model