Unified Modeling Language

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Unified Modeling Language

• A common vocabulary for talking about software
  design

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Models

• One of the most important steps in OO problem
  solving is the construction of a model.
• The model abstracts the essential details of the
  underlying problem from its usually complicated
  real world.
• The domain is the actual world from which the
  problem comes.
• Models consist of objects interacting by sending
  messages.

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The Importance Of UML

• UML provides tools for modeling problems in order
  to create software.
• UML provides a common vocabulary to the
  participants in the problem solving (whether a
  business analyst, designer, or programmer).

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UML Breakdown

• UML actually consists of several tools
• Use case diagrams
• Class diagrams
• Object diagrams
• Sequence diagrams
• Collaboration diagrams
• Statechart diagrams
• Activity diagrams
• Component diagrams
• Deployment diagrams

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Use Case Diagrams

• Use case diagrams depict the system from an
  external observers perspective.
• They describe what the system does rather than
  how.
• A scenario describes what happens when someone
  interacts with the system.
• Example scenario A patient calls the clinic to
  make an appointment for a yearly checkup. The
  receptionist finds the nearest empty time slot in
  the appointment book and schedules the
  appointment for that time slot.
• A use case is a summary of scenarios for a single
  task.

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Use Case Diagrams

• Use case diagrams consist of
• Actors
• Use cases
• Communications
• An actor is who or what initiates the events in a
  task.
• A communication association (or simply a
  communication) is a connection between actors and
  use cases.

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Example Use Case Diagram
Figure 1 Simple use case diagram
Figure 2 More complicated use case diagram
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Use Case Diagrams

• Use case diagrams are helpful in
• determining features new use cases generate new
  requirements
• communicating with clients simple notation can
  be understood by non-technical people
• generating test cases the scenarios suggest
  tests that can verify correct behavior

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Class Diagrams

• Class diagrams show the classes in the system and
  their relationships.
• Class diagrams are staticthey display who
  interacts but not how they interact.
• A class in UML is shown as a rectangle divided
  into three parts class name, attributes, and
  operations.

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Class Diagrams
Customer
class name
name address
attributes
getName
operations
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Example Class Diagram
Figure 3 Customer order example
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Class Diagrams

• Class diagrams can describe the following
  relationships
• association an association exists between two
  classes if an instance of one class must know
  about the other to perform its work.
• aggregation an association in which one class
  belongs to a collection.
• generalization inheritance

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Associations

• An association has two ends. One end may have a
  role name to clarify the relationship.
• A navigability arrow on an association shows the
  direction the association can be traversed.
• Multiplicity of an association end is the number
  of possible instances of the class associated
  with a single instance of the other end.

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Common Multiplicities
Multiplicities Meaning
0..1 zero or one instance
0.. or no limit on the number of instances (including none)
1 exactly one instance
1.. at least one instance
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Composition Aggregation

• Associations in which an object is part of a
  whole are aggregations.
• Composition is a strong association in which the
  part can belong to only one wholethe part cannot
  exist without the whole.
• Composition is denoted by a filled diamond at the
  whole end.

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Example Composition
Figure 4 Composition example
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Visibility

• Visibility (private, public, protected) can also
  be shown in class diagrams.
• Static members are underlined.
• Operations have the form
• ltaccess specifiergt ltnamegt ( ltparameter listgt)
  ltreturn typegt
• The parameter list shows each parameter type
  preceded by a colon.

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Visibility
Symbol Access
public
- private
protected
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Example Visibility
Figure 5 Visibility example
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Interfaces

• Interfaces can be shown in two ways
• shown similar to regular classes
• shown as lollipops or circles shows less
  detail
• Both notations use the inheritance arrow.

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Example Interface (1st notation)
Figure 6 Interfaces
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Example Interface (2nd notation)
Figure 7 Lollipop notation
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Object Diagrams

• Object diagrams show instances instead of
  classes. They are especially useful in
  describing recursive relationships.
• Each rectangle in the diagram corresponds to a
  single instance.
• Rectangles are labeled instanceNameclassName.

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Example Object Diagram
Figure 8 Class diagram
Figure 9 Object diagram (instantiation of above
class diagram)
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Interaction Diagram

• Interaction diagrams are dynamicthey describe
  how objects collaborate.
• There are two kinds of interaction diagrams
• sequence diagrams
• collaboration diagrams

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Sequence Diagrams

• A sequence diagrams shows what messages are sent
  to whom and when.
• They are organized according to time.
• Time progresses down the page.
• Objects are displayed left to right as they
  become relevant.

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Example Sequence Diagram
Figure 10 Making a hotel reservation
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Sequence Diagrams

• Each vertical dotted line is a lifeline
  representing the time the object exists.
• Each arrow is a message call.
• The arrows go from the sender to the top of the
  activation bar of the receiver.
• Activation bars represent the duration of the
  message.
• All UML diagrams can contain notes dog-eared
  rectangles containing clarifying text.
• Conditions are in square brackets.

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Collaboration Diagrams

• Collaboration diagrams focus on object roles
  rather than times that messages are sent.
• Each message in a collaboration diagram has a
  seqence number. The top-level message is
  numbered 1.
• Messages at the same level (sent during the same
  call) have the same prefix but with consecutive
  suffixes according to when they occur.

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Example Collaboration Diagram
Figure 11 Collaboration diagram for hotel
reservation
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Statechart Diagrams

• A statechart diagram depicts the possible states
  an object can be in and the transitions that
  change states.
• States are rounded rectangles.
• Transitions are arrows.
• Events or conditions that trigger transitions are
  written beside the arrows.
• Initial state is solid black circle.
• Final states are concentric white/black circles.

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Example Statechart Diagram
Figure 12 Online banking login
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Statechart Diagrams

• An action that occurs as a result of an event or
  condition is expressed as /action.
• Actions can occur inside states too. The enter,
  do, and exit events on a state trigger actions
  when the state is entered, once inside, and
  exited respectively.

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Activity Diagrams

• Activity diagrams are fancy flowcharts.
• Activity diagrams focus on the flow of activities
  involved in a single process.
• Activities are rounded rectangles.

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Example Activity Diagram
Figure 13 Withdrawing money from a bank account
through an ATM
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Activity Diagrams

• Swimlanes divide activities according to who
  performs them.
• A transition may branch into two or more mutually
  exclusive transitions.
• Guard expressions label transitions leaving a
  branch.
• A merge brings together multiple transitions
  (those created in the branch).
• A fork denotes parallel execution.
• A join is where parallel execution meets up.
  (One waits on another to complete before
  continuing).

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Component And Deployment Diagrams

• A component is a code module.
• Components are shown as rectangles with two tabs
  at upper left.
• Deployment diagrams show the physical
  configurations of software and hardware.
• Physical hardware is made up of nodes.
• Each components belongs on a node.

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Example Deployment Diagram
Figure 14 Real estate transactions
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UML Tools

• Software exists for UML creation.
• Some software can synchronize UML diagrams and
  code.
• Some software can generate code once UML diagram
  is completed.
• Rational Rose is currently the most popular
  software for UML creation.

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Works Cited

• Practical UML A Hands-On Introduction for
  Developers. http//www.togethersoft.com/services/
  practical_guides/umlonlinecourse/