Part VI: Design Continuous

1
Part VI Design Continuous

• Activity Diagams
• State Diagrams

2
Content

• Activity Diagams
• State Diagrams

3
Activity Diagrams
4
Activity Modeling

• a specialized type of behavioral modeling
• concerned with modeling the activities
• and responsibilities of elements.
• a special form of state machine to model
• the computations
• and workflow
• Represents the state of execution
• not states of objects
• applied in conjunction with
• sequence and collaboration modeling

5
Activity Diagrams

• widely used in analysis to model
• a use case flow
• flow between the use cases
• with no use of classes, objects, etc.
• but also in design to model
• details of operation
• details of algorithm

6
Using Activity Diagrams

• activity diagram can be
• attached to any modeling element
• for the purpose of modeling the behavior of that
  element.
• Activity diagrams are typically attached to
• use cases
• classes
• interfaces
• components
• nodes
• collaborations
• operations and methods

7
Action States

• Operation of Object Oriented systems
• a society of objects
• Elements communicate with one another
• each element has
• the responsibility of reacting
• to the communications it receives.
• An action state processing
• as an element fulfills a responsibility
• Example (the project management system states)
• Project Manager Enters Report Criteria
• Project Management System Generates Report
• Printer Prints Report

8
Types of action states

• Initial action state
• the first action state
• A final action state
• the last action state
• is shown using a bull's eye
• An activity diagram
• may have only one initial action state,
• but may have any number of final action states.

9
Flow Transitions

• shows how action states
• are ordered
• or sequenced.
• Whenever
• an action or subactivity state
• finishes its work,
• there is a transition
• out of the state into the next state
• types of flow transitions
• control-flow
• object-flow transitions

10
Control-Flow Transitions

• indicates
• the order of action states
• Once a source action state
• completes its processing,
• a target action state
• starts its processing

11
Example Control Flow Transitions

• task of generating a report
• for the project management system
• order of action states
• The Project Manager Enters Report Criteria
• The Project Management System
• Generates Report
• The Printer Prints Report

12
Control-flow transitions
13
Default transitions

• Control-flow transitions
• are also known as default transitions
• or automatic transitions,
• because
• they are unlabeled
• and are immediately triggered
• after the source action state
• completes processing.

14
Decisions

• A decision involves
• selecting one control-flow transition
• out of many control-flow transitions
• based upon a condition

15
Swimlanes

• a visual region in an activity diagram
• Represents
• use cases
• classes
• components
• organizational units
• in business modeling
• roles
• in workflow modeling
• indicates the element
• has responsibility
• for action states within the region

16
Object-Flow Transitions

• Indicates an action state
• input or output an object
• can modify object state
• An object-flow transition
• is shown as
• a dashed arrow
• between
• 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
17
Types of Object-Flow Transitions

• An action state uses an object as input
• show with object-flow transition arrow
• Point
• from the object
• to the action state.
• An action state updates or produces an object
• Show with the object-flow transition arrow
• Point
• from the action state
• to the object

18
Control-flow and object-flow transitions
Without unnecessary control-flow transitions
19
Signals

• A signal is a way of representing
• a package of information
• that is communicated asynchronously
• between two objects.
• A signal event occurs
• when an object receives a signal
• When an event is received
• by an object
• it may trigger a state transition in it

20
Sending Receiving Signals

• the signal called Order is sent to the
• MailOrderCompany external object
• we wait in the signal receipt
• for a signal called Goods delivered

21
Signals are classifiers

• Modeled as stereotyped classes.
• The purpose of a signal is
• to provide asynchronous communication of
  information
• between objects and so,
• unlike ordinary classes,
• they only have attributes
• and the single implicit operation
• send(targetSet)
• allows them to be sent to a set of target
  objects.
• As this operation is implicit,
• it is never actually shown on signal diagrams
• it is just assumed that it is there for every
  signal.
• The signal attributes
• specify the information content of the signal

22
Example GUI events

• a generalization hierarchy of raw GUI events
  modeled as signals

23
Concurrency

• selecting multiple transitions simultaneously

24
State Diagrams
25
State Diagrams

• also known as
• statechart diagrams
• state machines (in UML 2.0)
• depict the lifecycle of elements
• that make up a system
• State modeling
• is a specialized type of behavioral modeling
• concerned with modeling
• the lifecycle of an element

26
States Definition

• A state
• is a condition of being at a certain time.
• is drawn as a rounded rectangle
• with the name of the state in the center
• can be
• a passive quality,
• Example light objectgt On and Off.
• an active quality (object is doing something
• Example Person gt moving, sleeping, reading,
• Example coffeemaker gt Brewing

27
Simple States

• indicates a condition or situation of an element.
  
• Example
• the project management system
• Inactive
• is not available to its users,
• because it is not started or has been shut down
• Active
• started and available to its users
• Suspended
• has encountered some severe error,
• Possible reason
• is running low on secondary storage
• requires user intervention

28
Initial and Final States

• Initial state
• the state of an element ,
• when it is created.
• is shown with a small solid filled circle.
• A final state
• the state of an element
• when it is destroyed.
• is shown with
• a circle surrounding a small solid filled circle
• a bull's eye

29
Transitions

• A transition,
• shown with an arrow
• represents
• a change of states
• from a source state to a target state
• A transition description,
• written along the arrow,
• describes the circumstances
• causing the state change to occur.

30
Trigger

• A trigger is
• an event cause a transition.
• Example
• User input processing systems
• a keystroke trigger
• may cause the system to change states
• from Gathering input
• to Processing input.

31
Transition Variations

• A trigger with no guard
• the transition is taken
• when the trigger occurs.
• This is useful
• for modeling a state change
• in response to an event.
• A trigger with a guard
• the transition is taken
• when the trigger occurs
• if the guard evaluates to true.
• Otherwise, the transition isn't taken.
• Combining a trigger and a guard is useful
• for modeling a transition is blocked
• depending on a condition.
• Neither a trigger nor a guard are specified,
• the transition is taken immediately
• after the source state's internal behavior

32
The life cycle of an object

• the life cycle of an AccountApplication object
• as it passes from pending
• to approved or rejected
• and then to finalizing

33
Example how to use

• State diagram modeling a troll in a FPS game
• FPS first-person shooter
• the troll's behavior is determined by his state

34
Composite States

• A composite state is a state
• contains one or more state diagrams.
• Each diagram belongs to a region,
• regions are divided by a dotted line
• A state in a region is referred to as a
• substate of the composite state.
• Composite states work as follows
• when the composite state becomes active,
• the initial pseudostate of each region becomes
  active,
• and the contained state diagrams begin executing.
  
• if a trigger on the composite state occurs
• The contained state diagrams are interrupted

35
Composite States Example

• Composite states contain
• one or more state diagrams
• execute in parallel

36
Advanced Pseudostates

• A choice pseudostate
• used to emphasize a Boolean condition
• determines
• which transition is followed.
• has guards
• represented on outgoing transitions
• the transition depends on the guard.

37
Fork and join pseudostates

• show branching
• into concurrent states
• and then rejoining

38
Signals

• transition-oriented view
• to draw attention
• to transitions and transition behavior
• using special icons for transitions.

39
End of Chapter