Introduction to UML

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Introduction to UML

• By
• Prof. Aiman Hanna
• Department of Computer Science, Concordia
  University,
• Montreal, Canada

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What is UML?

• It is a notation that is a set of diagrams and
  diagram elements that may be arranged to describe
  the design of a software system.
• UML is not a process, nor is it a method
  comprising a notation and a process.
• The OMG specification states
• The Unified Modeling Language (UML) is a
  graphical language for visualizing, specifying,
  constructing, and documenting the artifacts of a
  software-intensive system. The UML offers a
  standard way to write a system's blueprints,
  including conceptual things such as business
  processes and system functions as well as
  concrete things such as programming language
  statements, database schemas, and reusable
  software components."

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Why use UML?

• In a software context, formal design becomes
  increasingly important as the size and complexity
  of the software grows.
• UML provides facilities for visualizing,
  specifying, constructing, and documenting the
  software this will likely increase the success
  chances of the software and possibly
  significantly reduces its cost.

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Why UML, is there something else?

• The complexity and nature of different software
  vary tremendously. As a result it is unlikely
  that single set of notation be the best when
  representing any software.
• UML however claims to be a universal notation
  that is suitable for all problems.
• After practically (and intensively) utilizing
  UML, you might be able to judge whether or not
  this claim holds.

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History of UML

• In the beginning, there were three principal
  methods
• The Booch method, devised by Grady Booch,
• Object-oriented Modeling Technique (OMT), devised
  by Jim Rumbaugh,
• Object-oriented Software Engineering (also known
  as Objectory), devised by Ivar Jacobson.
• The three methods had many ideas on common, yet
  different notation for expressing those ideas
  (for example, OMT classes were represented by
  rectangle boxes, whereas in Booch methods they
  were represented as cloud shapes). Other ideas
  were introduced only by one or the other of the
  three methods.
• UML combined the best bits of all three with a
  common notation.

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History of UML

• In terms of time, here is the history
• 1994 Jim Rumbaugh left General Electric to join
  Grady Booch ar Rational Software, so as to merge
  their methods and achieve standardization across
  the industry.
• 1995 Booch and Rumbaugh published version 8 of
  the Unified method. Rational Software buys
  Objectory and Ivar Jacobson joins the company.
• 1997 Booch, Rumbaugh and Jacobson release
  (through Rational) a proposal of version 1 of
  UML.
• 1997 UML version 1.1 was adopted by The Object
  Management Group (OMG), a non-profit
  organization, previously best known for the CORBA
  standard. It is advisable that you visit
  www.omg.org for much more information on UML.

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Few Notes Possibly Negative!

• A diagramming notation should be as simple as
  possible. UML is very complex. The notation
  summary is relatively big and consists of many
  sections.
• Due to its diagram complexity, it is not easy to
  use hand-writing for UML representation. One must
  use some other software, such as MS-Visio, in
  order to draw UML diagrams.
• Due to its complexity, a significant amount of
  time, and an intensive amount of work, may be
  needed before becoming familiar with UML.

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Types of UML diagrams

• Each UML diagram is designed to let developers
  and customers view a software system from a
  different perspective and in varying degrees of
  abstraction. UML diagrams commonly created in
  visual modeling tools such as Describe include

Use Case Diagram Displays the relationship among actors and use cases.
Class Diagram Models class structure and contents using design elements such as classes, packages and objects. It also displays relationships such as containment, inheritance, associations and others.
State Diagram Displays the sequences of states that an object of an interaction goes through during its life in response to received stimuli, together with its responses and actions.
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Types of UML diagrams
Collaboration Diagram Displays an interaction organized around the objects and their links to one another. Numbers are used to show the sequence of messages.
Activity Diagram Displays a special state diagram where most of the states are action states and most of the transitions are triggered by completion of the actions in the source states. This diagram focuses on flows driven by internal processing.
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Types of UML diagrams
Component Diagram Displays the high level packaged structure of the code itself. Dependencies among components are shown, including source code components, binary code components, and executable components. Some components exist at compile time, at link time, at run times well as at more than one time.
Deployment Diagram Displays the configuration of run-time processing elements and the software components, processes, and objects that live on them. Software component instances represent run-time manifestations of code units.
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Useful UML Links Tutorilas

• There is a mass of useful UML resources and
  tutorials in the Internet, here are few of them
  
• http//www.omg.org
• http//www.holub.com/goodies/uml/index.html
• http//www.smartdraw.com/resources/centers/uml/uml
  .htm
• http//www.sparxsystems.com.au/UML_Tutorial.htm