This presentation details methods for analyzing a use case in order to determine it is complete. It derives requirements from the use case.

1. 2009 copyright Leslie Munday University
Realizing The Application Use Case
Analysis And Design Discipline

2. Leslie Munday 2008
Precursor
 In order to understand the material in this
course, you should have a knowledge of
UML, a UML modeling tool and equivalent
knowledge of the following presentations:
 Working With AUC Documents.
 Use Case Modeling Notation.
 Working With Class Diagrams.
 What Is A State Transition Diagram?
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3. Leslie Munday 2008
Overview
 In this lesson you will learn :
 how to add analysis information to a use case
diagram.
 how to identify classes, their attributes and
relationships from the use case model.
 how to discover class operations.
 how to map the use case to an analysis class
diagram.
 how to map an activity diagram to an analysis
sequence diagram.
 how to map state transition diagrams to classes.
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4. Leslie Munday 2008
Use Case Recap
 A use case comprises the following components as a minimum:
 Description – High level view of the contents of the use case.
 Maximum Usage – How often that this use case could potentially
be executed.
 Primary Actor – The actor that initiates the use case.
 Secondary Actors – Non-initiating actors that interface with the use
case.
 Preconditions – The state of the system prior to the use case
executing.
 Basic Flow – The main or expected path the use case executes.
 Alternate Flows – Alternate paths the use case may execute in
order to achieve its goal.
 Extension Flows – Alternate paths that cause the use case to fail to
achieve its goal.
 Postconditions – The possible states of the system after the use
case has completed.
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5. Leslie Munday 2008
Modeling Recap
 The initial node takes the name
of the preconditions.
 A control flow takes the name
of an externally visible event.
 A decision describes an
alternate of extension point.
 A merge describes an alternate
path returning to the basic flow.
 A final node describes a
postcondition of the system.
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6. Leslie Munday 2008
Adding Objects
 For every activity in the activity diagram
discover what information is input to the
activity and what information is output from
the activity.
 Identify the appropriate object for this data
and indicate whether the activity is writing
to the object or reading from the object
using directed object flows.
 Label the object flow with the name of the
data.
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7. Leslie Munday 2008
Dematerializer Objects 1
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8. Leslie Munday 2008
Dematerializer Objects 2
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9. Leslie Munday 2008
The Objects
 Notice that the objects take the name of the ‘real-
life’ object that they interface with.
 door – operates the door to the dematerializer.
 transmitter – interfaces to the Transmitter actor.
 cargoHandler – controls securing the cargo.
 vacuumPump – controls removing air.
 deconstructor – controls the heart of the dematrializer.
 blueprintManager – is an interface to the
BlueprintManger actor.
 airSensor – monitors the air pressure.
 airValve – controls the air pressure.
 powerManager – controls the power to the
dematerializer.
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10. Leslie Munday 2008
Class Diagram
 Create a class diagram and copy the object
classes onto the diagram.
 Add the operations and data from the
activity diagram to the classes.
 Connect the classes with relationships and
add new classes as required.
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11. Leslie Munday 2008
Dematerializer Class Diagram
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 The Cargo
class has
been added
to identify
the attributes
of the cargo.
These will be
input to the
system as
parameters
of the
‘deconstruct’
command.

12. Leslie Munday 2008
Draw A Sequence Diagram
 Create a sequence diagram.
 Add an instance of the primary actor of the use case
on the left side of the sequence diagram.
 Add instances of secondary actors on the right side
of the sequence diagram.
 Place instances of the classes on the diagram,
roughly in the sequence in which they are accessed
by the use case.
 For every control flow in the basic flow of the use
case activity diagram, draw equivalent message
flows on the sequence diagram.
 Add operations, as necessary, to the classes that
represent the messages on the sequence diagram.
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13. Leslie Munday 2008
Corresponding Sequence Diagram
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14. Leslie Munday 2008
Sequence Diagram Explained
 The sequence diagram is only complete up
to step 5 of the use case.
 Notice that the Cargo object is used to
control the internal messages between the
other objects.
 Because the sequence diagram implies a
time scale running vertically down the page,
it is very difficult to show parallel flows on a
sequence diagram.
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15. Leslie Munday 2008
Updated Class Diagram
 The cargo
class has
been
updated to
reflect the
operations
discovered
on the
sequence
diagram.
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16. Leslie Munday 2008
Alternative and Extending Flows
 Repeat drawing a sequence diagram for
each alternative and extending flow.
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17. Leslie Munday 2008
State Transition Diagrams
 Another tool that helps us to determine if there
is any missing data or operations from our
model, is the STD.
 For each class in the class diagram, where its
states are non-trivial, i.e. there is more than
one state, create a STD.
 Identify all of the possible states that the class
may take and all potential transitions between
those states.
 Ensure that all data and operations used by
the STD are captured within the class that the
STD is modeling.
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18. Leslie Munday 2008
AirValve STD
 Notice that from the
class diagram we see
2 states, ‘Open’ and
‘Closed’.
 Once we start
modeling, we
discovered another 2
states and a potential
data element, ‘failed’.
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19. Leslie Munday 2008
Update The Class Diagram
 We have
added a
‘failureState’
attribute to
the valve
class.
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20. Leslie Munday 2008
Revisit the Use Case Activity
 The use case did not consider what to do if the air valve
failed.
 We need to add an alternate path to the use case
describes the action to be taken in the event of a valve
failure, extension point A3.
 Notice the new extension does not mention the valve, it
abstracts the functionality to the vacuum equipment
without stating what that comprises.
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Extension Points
•A3 Vacuum equipment broke:
•12 At step 6 the system cannot create a vacuum, the system unsecures the cargo.
•13. When the cago is released the system opens the door.
The use case ends.

21. Leslie Munday 2008
Summary
 In this presentation you learned:
 how to add objects to a use case activity diagram.
 how to convert those objects into classes on a class diagram, and
add preliminary data and operations.
 how to model the use case and its associated classes using
sequence diagrams.
 how the sequence diagrams are used to capture more detailed
operations of the classes.
 how to model a class with a STD.
 how to identify more information for the class diagram from the
events in the STD.
 how to add identify functionality from a use case by analyzing the
classes that implement the use case.
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22. Leslie Munday 2008
Test Your Knowledge
 Add objects to the ATM example use case.
 Create a class diagram for the ATM application.
 Create a sequence diagram for each path through
the ATM application use case.
 Model the ATM classes with STDs.
 Update the use case from operations that are
discovered during the modeling process.
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