Modeling Object State Types, Attributes

Modeling Object State Types, Attributes, and Associations... 

Chapter 2, Static Models Object Attributes and Invariants, describes how attributes abstract variations in the implementation of object state. Chapter 3, Behavior Models Object Types and Operations, describes how operation specifications describe externally visible behavior of an object, independently of algorithmic and representation decisions. 

UML treats attributes on a type as abstract but does not permit attributes to take parameters instead, you can use an operation that has been marked as read-only. Catalysis encourages a slightly different way of thinking about an object Some things are abstractions of its state, and others are abstractions of its behaviors. Attributes, parameterized attributes, and invariants all help to define the model of state operation specifications define the behaviors. There are no preconditions and postconditions on attributes, because they represent state there can be conditional invariants on an attribute, and there can be syntactic shortcuts for expressing them, but they are not pre- and postconditions ... 

In Catalysis, we can use refinement to model abstract objects that do not necessarily correspond to an instance of an OOP class and abstract actions that may not correspond to a single OOP message send. Based on this, we can use all the modeling techniques— including attributes, types, collaborations, refinement, justifications, interactions, snapshots, and states—to describe architectural models and their rationale. 

A model of real-world objects and their interactions—or rather, some users understanding of them—is called a business model. The outcome of each interaction depends on (1) the types to which its participant objects belong and (2) the states they are in at the time. For any participant types, you can describe the effects of an action by relating the values of the attributes before and after any occurrence of that action. 

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