CS551 Behavior Models: Object Types and Operations (Chap. 3 of UML)

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CS551 Behavior Models Object Types and
Operations (Chap. 3 of UML)

• Yugi Lee
• STB 555
• [phone]
• yugi_at_cstp.umkc.edu
• www.cstp.umkc.edu/yugi

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Subtypes and Type Extension

• Class
• an object-oriented programming (OOP) construct
  (implementation of some objects)
• Type
• a specification of a set of objects
• Subclassing
• inheriting implementation with certain forms of
  overriding of implementation
• Subtyping
• no overriding of specifications, only extension.

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Classes Types
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Type Expression

• Subtype
• Cow Mammal
• Multiple Supertypes
• Bat Mammal Flier
• Type Exclusion
• TA1 TA2
• Type Partitioning
• TA TA1TA2

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State Type

• A set of objects defined by a predicate
• Objects are classified based on a condition and
  define resultant properties they will have
• An employee is a person with an employer
  employees have a salary and can get fired.

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State Chart

• Each state is a Boolean attribute
• The structure of states defines invariants across
  these attributes.
• States are
• mutually exclusive.
• can be nested inside a state.
• can be divided into concurrent sections

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State Transitions as Actions
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Translating State Transitions to Actions
action Typea1 pre s1 precond post s2
postcond

• action Pumphangup
• pre ready
• post idle
• action Pumppickup
• pre idle
• post ready

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State Charts of Specification Types
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State Charts of Specification Types
action Drawing_Editorselect (shapeShape) post
current_doc_contents -gt forAll ( s
((s.selected sshape)_at_pre gt
s.unselected) ((s.unselected sshape)_at_pre
gt s.selected))
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Sequence Expression

• S1 S2
• S1 always precedes S2
• S1 S2
• S1 or S2
• S1
• Any number of repetitions
• of S1
• S1 S2
• S1 concurrent with S2

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The Meaning of Containment
Containment represents a localized view, which is
a state type of the common usage.
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Type Specifications Summary

• An objects behavior (or part of it) can be
  described with a type specification.
• A type specification is a set of action
  specifications
• A postcondition a relationship between the
  states before and after any of its occurrences
  takes place.
• A precondition when the associated postcondition
  is applicable.