An Introduction to the Unified Modeling Language

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An Introduction to the Unified Modeling Language

• Craig A. Struble, Ph.D.
• Department of Mathematics, Statistics, and
  Computer Science
• Marquette University

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Overview

• History
• Views
• Use Cases
• Object Modeling
• Dynamic Modeling
• Turning models into code
• Tools, etc.

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History

• Three Amigos
• Rumbaugh, Booch, Jacobson
• Several competing methods for OO design and
  modeling
• Developed 1994-1997
• Submitted to OMG and approved
• UML 2 approved in 2003

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UML

• Modeling
• Creating an abstraction of a system, process,
  etc.
• Language
• A means of communicating between stakeholders
• Process (not strictly UML)
• The steps taken to analyze, model, and implement
  a software system.

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Views of Software

• Many perspectives exist on software
• User
• What the users see and interact with
• Static
• The code when it is not being executed
• Classes, modules, directory structure, etc.
• Dynamic
• The behavior of the code and data as the system
  is executed
• Objects, traces of method/function calls, log
  files, etc.

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When to Model?

• Depends on software development process
• Waterfall, modeling is done before coding starts
• Spiral, modeling and coding are interleaved
• Rapid prototyping, modeling happens as needed
• In general, modeling is a good idea whenever a
  user, analyst, or developer on the team does not
  completely understand the system
• Remember, documentation is a communication tool
  for all parties

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Use Case Modeling

• Primarily used to gather requirements
• Define functionality of the system
• Forms the basis of system tests
• Provides ability to track requirements to
  classes/objects
• Communicate with all stakeholders
• Users, designers, marketing, etc.

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Use Case Modeling

• The system is what is being modeled
• An actor is someone or something that interacts
  with the system
• A use-case represents functionality for an actor

Use Case
System
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Example
From UML 2 Toolkit
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Use Cases

• a set of actions performed by a system, which
  yields an observable result that is, typically,
  of value for one or more actors or other
  stakeholders of the system.
• Use cases
• Are initiated by some actor
• Provides value to some actor
• Are complete

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Use Cases

• Constructing a complete use case diagram is
  usually easier (and less time consuming) than
  writing the requirements for each use case
• The use case descriptions are typically written
  textually (like weve already done) and in full
  detail.

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Relationships

• Actors and use-cases can have relationships.
• Actors are associated with use-cases
• Actors may be generalizations of other actors
• Use cases may generalize, extend, or include
  other use cases.

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Another Example
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Exercise

• Lets draw a reasonably complete use case diagram
  for the antisense project.

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Modeling Static Aspects

• What most developers think about when modeling
  software
• What are the major data being manipulated?
• How should system behavior be organized?
• Leads to identifying objects and classes in the
  system

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Objects vs. Classes

• An object is a concrete example of something
  being modeled
• E.G. my 2003 Toyota Matrix, the dead birch tree
  in my back yard, me
• A class is a family of objects having similar
  characteristics or attributes
• E.G. automobiles, trees, people, etc.
• An object is an instance of a class

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Representing Classes
Attributes
Car
Name
- registration number String speed
Integer direction Real
Operations
accelerate(rate Integer) void turn(angle
Real) void
Visibility - is private is public is package
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Associations
Multiplicity
Multiplicity
Assocation gt
Class1
Class2
lt Association
1..
0..
Owns gt
Person
Car
lt Owned By
A person owns 0 or more cars. A car is owned by
1 or more people.
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Relationships

• Identifies how classes/objects are related to one
  another
• Association
• A connection between classes
• Generalization
• One class is more general than another
• Dependency
• One (dependent) class/object is changed when
  another (independent) class/object is changed
• Abstraction
• Two or more descriptions of the same thing at
  different levels. A class is an abstraction of an
  object