Why We Model

1
Why We Model?

• Keng Siau
• University of Nebraska-Lincoln

2
Modeling and Model

• Modeling
• A central part of all the activities that lead up
  to the deployment of good software
• Model
• A simplification of reality
• Provides the blueprint of a system

3
Objectives of Modeling

• To communicate the desired structure and behavior
  of the system
• To visualize and control the systems
  architecture
• To better understand the system we are building
• To serve as a template that guide us in
  constructing a system
• To expose opportunities for simplification and
  reuse
• To document the decisions made
• To manage risk

4
Principles of Modeling

• The choice of what models to create has a
  profound influence on how a problem is attacked
  and how a solution is shaped
• Every model may be expressed at different levels
  of precision

5
Principles of Modeling

• The best models are connected to reality
• No single model is sufficient. Every nontrivial
  system is best approached through a small set of
  nearly independent models

6
Traditional vs. Object-Orientated Approach

• Traditional view
• an algorithm perspective
• main building block is the procedure or function
• OO view
• main building block is the object or class
• an object is a thing
• a class is a description of a set of common
  objects

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Object

• Every object has
• Identity
• you can name it or distinguish it from other
  objects
• State
• theres generally some data associated with it
• Behavior
• you can do things to the object
• the object can do things to other objects

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Purpose of UML

• To support object-oriented systems
• visualization
• specification
• construction
• documentation