Part VI: Design Continuous
Activity Diagams
State Diagrams
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Content
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Activity Diagams
State Diagrams
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Activity Diagrams
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Activity Modeling
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a specialized type of behavioral modeling
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a special form of state machine to model
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not states of objects
applied in conjunction with
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the computations
and workflow
Represents the state of execution
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concerned with modeling the activities
and responsibilities of elements.
sequence and collaboration modeling
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Activity Diagrams
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widely used in analysis to model
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but also in design to model
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a use case flow
flow between the use cases
with no use of classes, objects, etc.
details of operation
details of algorithm
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Using Activity Diagrams
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activity diagram can be
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Activity diagrams are typically attached to
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attached to any modeling element
for the purpose of modeling the behavior of that
element.
use cases
classes
interfaces
components
nodes
collaborations
operations and methods
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Action States
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Operation of Object Oriented systems
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a society of objects
Elements communicate with one another
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each element has
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An action state processing
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as an element fulfills a responsibility
Example (the project management system states)
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the responsibility of reacting
to the communications it receives.
Project Manager Enters Report Criteria
Project Management System Generates Report
Printer Prints Report
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Types of action states
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Initial action state
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A final action state
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the last action state
is shown using “a bull's eye”
An activity diagram
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the first action state
may have only one initial action state,
but may have any number of final action states.
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Flow Transitions
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shows how action states
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are ordered
or sequenced.
Whenever
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an action or subactivity state
finishes its work,
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there is a transition
out of the state into the next state
types of flow transitions:
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control-flow
object-flow transitions
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Control-Flow Transitions
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indicates
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Once a source action state
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completes its processing,
a target action state
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the order of action states
starts its processing
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Example Control Flow Transitions
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task of generating a report
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for the project management system
order of action states:
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The Project Manager Enters Report Criteria
The Project Management System
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Generates Report
The Printer Prints Report
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Control-flow transitions
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Default transitions
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Control-flow transitions
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are also known as default transitions
or automatic transitions,
because
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they are unlabeled
and are immediately triggered
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after the source action state
completes processing.
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Decisions
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A decision involves
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selecting one control-flow
transition
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out of many control-flow
transitions
based upon a condition
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Swimlanes
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a visual region in an activity
diagram
Represents
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use cases
classes
components
organizational units
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roles
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in business modeling
in workflow modeling
indicates the element
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has responsibility
for action states within the
region
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Object-Flow Transitions
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Indicates an action
state
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input or output an
object
can modify object state
An object-flow
transition
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is shown as
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a dashed arrow
between
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an action state
and an object.
Activities may input and output objects and can modify object state
show this on an activity diagram as an object flow
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Types of Object-Flow Transitions
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An action state uses an object as input:
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show with object-flow transition arrow
Point
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An action state updates or produces an object:
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Show with the object-flow transition arrow
Point
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from the object
to the action state.
from the action state
to the object
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Control-flow and object-flow transitions
Without unnecessary control-flow transitions
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Signals
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A signal is a way of representing
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a package of information
that is communicated asynchronously
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A signal event occurs
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when an object receives a signal
When an event is received
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between two objects.
by an object
it may trigger a state transition in it
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Sending & Receiving Signals
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the signal called
Order is sent to the
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:MailOrderCompany
external object
we wait in the signal
receipt
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for a signal called
Goods delivered
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Signals are classifiers
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Modeled as stereotyped classes.
The purpose of a signal is
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to provide asynchronous communication of information
between objects and so,
unlike ordinary classes,
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they only have attributes
and the single implicit operation
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send(targetSet)
allows them to be sent to a set of target objects.
As this operation is implicit,
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The signal attributes
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it is never actually shown on signal diagrams
it is just assumed that it is there for every signal.
specify the information content of the signal
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Example: GUI events
a generalization hierarchy of raw GUI events modeled as signals
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Concurrency
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selecting multiple transitions simultaneously
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State Diagrams
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State Diagrams
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also known as
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depict the lifecycle of elements
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statechart diagrams
state machines (in UML 2.0)
that make up a system
State modeling
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is a specialized type of behavioral modeling
concerned with modeling
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the lifecycle of an element
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States: Definition
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A state
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is a condition of being at a certain time.
is drawn as a rounded rectangle
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with the name of the state in the center
can be
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a passive quality,
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an active quality (object is doing something
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Example: light object=> On and Off.
Example: Person => moving, sleeping, reading, …
Example: coffeemaker => Brewing
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Simple States
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indicates a condition or situation of an element.
Example:
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the project management system
Inactive
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Active
 started and available to its users
Suspended
 has encountered some severe error,
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Possible reason:
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is running low on secondary storage
requires user intervention
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Initial and Final States
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Initial state
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the state of an element ,
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when it is created.
is shown with a small solid filled circle.
A final state
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the state of an element
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is shown with
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when it is destroyed.
a circle surrounding a small solid filled
circle
a bull's eye
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Transitions
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A transition,
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shown with an arrow
represents
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a change of states
from a source state to a
target state
A transition description,
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written along the arrow,
describes the
circumstances
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causing the state change to
occur.
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Trigger
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A trigger is
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an event cause a transition.
Example:
User input processing systems
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a keystroke trigger
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may cause the system to change states
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from Gathering input
to Processing input.
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Transition Variations
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A trigger with no guard
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the transition is taken
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This is useful
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for modeling a state change
in response to an event.
A trigger with a guard
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the transition is taken
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when the trigger occurs
if the guard evaluates to true.
Otherwise, the transition isn't taken.
Combining a trigger and a guard is
useful
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when the trigger occurs.
for modeling a transition is blocked
depending on a condition.
Neither a trigger nor a guard are
specified,
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the transition is taken immediately
after the source state's internal
behavior
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The life cycle of an object
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the life cycle of an AccountApplication object
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as it passes from pending
to approved or rejected
and then to finalizing
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Example how to use
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State diagram modeling a troll in a FPS game
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FPS: first-person shooter
the troll's behavior is determined by his state
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Composite States
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A composite state is a state
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contains one or more state diagrams.
Each diagram belongs to a region,
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A state in a region is referred to as a
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substate of the composite state.
Composite states work as follows:
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when the composite state becomes active,
the initial pseudostate of each region becomes active,
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and the contained state diagrams begin executing.
if a trigger on the composite state occurs
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regions are divided by a dotted line
The contained state diagrams are interrupted
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Composite States Example
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Composite states contain
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one or more state diagrams;
execute in parallel
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Advanced Pseudostates
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A choice pseudostate
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determines
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has guards
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used to emphasize a Boolean condition
represented on outgoing transitions
the transition depends on the guard.
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Fork and join pseudostates
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show branching
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into concurrent states
and then rejoining
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Signals
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transition-oriented view:
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to draw attention
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to transitions and transition behavior
using special icons for transitions.
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End of Chapter
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