2 cissp ® Official Study Guide Eighth Edition

Message
A message is a communication to or input of an object.
Method
A method is internal code that defines the actions an object performs in response 
to a message.
Behavior
The results or output exhibited by an object is a behavior. Behaviors are the 
results of a message being processed through a method.
Class
A collection of the common methods from a set of objects that defines the behavior 
of those objects is a class.
Instance
Objects are instances of or examples of classes that contain their methods.

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Introducing Systems Development Controls 
875
Inheritance
Inheritance occurs when methods from a class (parent or superclass) are 
inherited by another subclass (child).
Delegation
Delegation is the forwarding of a request by an object to another object or del-
egate. An object delegates if it does not have a method to handle the message.
Polymorphism
A polymorphism is the characteristic of an object that allows it to respond 
with different behaviors to the same message or method because of changes in external 
conditions.
Cohesion
Cohesion describes the strength of the relationship between the purposes of the 
methods within the same class.
Coupling
Coupling is the level of interaction between objects. Lower coupling means less 
interaction. Lower coupling provides better software design because objects are more inde-
pendent. Lower coupling is easier to troubleshoot and update. Objects that have low cohe-
sion require lots of assistance from other objects to perform tasks and have high coupling.
Assurance
To ensure that the security control mechanisms built into a new application properly imple-
ment the security policy throughout the lifecycle of the system, administrators use 
assur-
ance procedures
. Assurance procedures are simply formalized processes by which trust is 
built into the lifecycle of a system. The Common Criteria provides a standardized approach 
to assurance used in government settings.