In this chapter
The real and conceptual world of instances
The terms "instance" and "object" are largely synonymous, so, for the most part, they may be used interchangeably. An instance is a concrete manifestation of an abstraction to which a set of operations may be applied and which may have a state that stores the effects of the operation.
|
See Chapter 15 for a discussion of internal structure, which is preferable when dealing with prototypical objects and roles. |
You use instances to model concrete things that live in the real world. Almost every building block in the UML participates in this class/object dichotomy. For example, you can have use cases and use case instances, nodes and node instances, associations and association instances, and so on.