CS%204233%20Review

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CS 4233 Review

• Feb 25 2003

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Outline

• Previous Business
• My.wpi.edu contains all grades to date for course
• Review and contact TA/prof for questions
• New Business
• HW5 solution due tomorrow 500 PM

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TAOO Questions

• What is the difference between links and
  associations?
• What is the practical impact of maintaining a
  bidirectional association?
• What is difference between aggregation and
  composition?
• What is difference between (1) Class C extends
  class A and (2) Class C uses class A as a
  servant class.

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TAOO Questions

• How are N-ary relationships implemented?
• Describe associations and links
• How are core operations relevant to N-ary
  relationships?
• How is a collection manager different from a
  container?
• Backward Containment vs. Forward Containment

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Java and OO

• Polymorphism, Sub-classes
• Interfaces, Sub-interfaces
• Methods
• Access (public, protected, private)
• Static methods

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Model View Controller

• MVC
• its variations
• responsibilities assigned to M, V, and C
• Use in GUIs
• Precursor to EBC

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Entity Boundary Controller

• EBC as consolidated approach to analysis
• Use cases ? Control, Boundary objects
• Domain Analysis ? Entity objects
• Describe interactions between controllers
• Controllers can be abstract to represent
  commonalities
• Specialized subclasses contain variations

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EBC

• All objects are not created equal
• Entity ? Represent persistent information
  required to implement desired system
• Boundary ? Represent interactions between actors
  and system
• Control ? Represent tasks that are performed by
  user and supported by system

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EBC

• Boundary object presented to user
• Event/action takes place
• Controller created (or invoked) to manage
  behavior
• Controller may display addl boundary
• Controller manages updates to entities and
  boundaries

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Object properties

• Cohesion
• Coupling
• Communication with other objects
• Sequence diagrams

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Law of Demeter

• Within a method, messages can only be sent to
• Its enclosing object
• A parameter of the method
• For pragmatic reasons includes global objects
• Attributes of the enclosing object
• Includes elements of a collection
• An object returned by a method of the enclosing
  object
• An object created within the method

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Demeter Summary

• Guideline for design
• Many reasons for breaking its laws
• Most are pragmatic and therefore unsound
• Replace micro-management with delegation

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Design Patterns

• Creational
• Singleton
• Restrict access to the instance(s) of a class
• Abstract Factory
• Provide an interface for creating families of
  related objects without specifying their concrete
  classes
• Concrete Factory
• Consolidate all constructors in one place
• Factory Method
• Delegate construction to subclasses

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Design Patterns

• Behavioral
• Iterator
• Access elements of an aggregate object
  sequentially without exposing underlying
  representation
• Visitor
• Define a new operation to be performed on
  elements of an object structure
• Avoid changing the classes of the elements on
  which the visitor operates

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Design Patterns

• Behavioral
• Template Method
• Define skeleton of an algorithm, deferring steps
  to subclasses
• Mediator
• Encapsulate how a set of objects interact
• Command
• Encapsulate a request as an object