Instances and Object Diagrams

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Instances and Object Diagrams

• Reporter???

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Abstractions and Instances

• Abstraction the ideal essence of a thing
• Instance a concrete manifestation of an
  abstraction
• a set of operations may be applied and may have a
  state that stores the effects of the operation
• not stands alone, always tied to an abstraction

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Objects

• is synonymous to instance
• something that takes up space in the real or
  conceptual world
• it is possible to change during the abstraction
  of that object
• lives within the context of an operation, a
  component, or a node

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Named, Anonymous, Multiple, and Orphan Instances
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Object State
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Standard Elements

• Stereotypes
• instanceOf
• instantiate
• become
• copy
• transient

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Modeling Concrete Instance
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Modeling Prototypical Instances
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Object Diagrams

• model the instances of things contained in class
  diagram
• a diagram that shows a set of objects and their
  relationship at a point of time
• covers a set of instances of the things found in
  a class diagram
• expresses the static part of an interaction

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An Object Diagram
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Contents

• Particular contents
• Objects
• Links
• Common contents
• name, notes, package and subsystem

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Common uses

• model the static design view or static process
  view of a system
• model static data structure
• visualize, specify, construct, and document the
  existence of certain instances in the system,
  together with their relationships to one another

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Modeling Object Structures
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Object Diagram Properties

• no single object diagram need capture everything
  about a systems design or process view
• reflect some of the concrete or prototypical
  objects that live in the running system