Object Modeling with OMG UML Tutorial Series
Behavioral Modeling
Gunnar Övergaard, Bran Selic, Conrad
Bock and Morgan Björkander
UML Revision Task Force
© 1999-2001 OMG and Contributors: Crossmeta, EDS, IBM, Enea Data, Hewlett-Packard, IntelliCorp, Kabira Technologies, Klasse Objecten,
Rational Software, Telelogic, Unisys
1
Overview
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!
!
Tutorial series
UML Quick Tour
Behavioral Modeling
!
Part 1: Interactions and Collaborations
!
!
Part 2: Statecharts
!
!
!
Gunnar Övergaard, Jaczone AB
Bran Selic, Rational Software
Morgan Björkander, Telelogic
Part 3: Activity Graphs
!
Conrad Bock, Kabira Technologies
Behavioral Modeling with UML
2
Tutorial Series
!
!
!
Lecture 1: Introduction to UML:
Structural and Use Case Modeling
Lecture 2: Behavioral Modeling with
UML
Lecture 3: Advanced Modeling with UML
[Note: This version of the tutorial series is based on OMG UML
Specification v. 1.4, UML Revision Task Force recommended final draft,
OMG doc# ad/01-02-13.]
Behavioral Modeling with UML
3
Tutorial Goals
!
What you will learn:
!
!
!
!
!
!
what the UML is and what is it not
UML’s basic constructs, rules and diagram
techniques
how the UML can model large, complex systems
how the UML can specify systems in an
implementation-independent manner
how UML, XMI and MOF can facilitate metadata
integration
What you will not learn:
!
!
!
Object Modeling
Development Methods or Processes
Metamodeling
Behavioral Modeling with UML
4
Quick Tour
!
The UML is a graphical language for
!
!
!
!
!
!
!
!
specifying
visualizing
constructing
documenting
the artifacts of software systems
Added to the list of OMG adopted technologies in
November 1997 as UML 1.1
Most recent minor revision is UML 1.3, adopted in
November 1999
Next minor revision will be UML 1.4, planned to be
adopted in Q2 2001
Next major revision will be UML 2.0, planned to be
completed in 2002
Behavioral Modeling with UML
5
UML Goals
!
!
!
!
!
!
!
Define an easy-to-learn but semantically rich visual
modeling language
Unify the Booch, OMT, and Objectory modeling
languages
Include ideas from other modeling languages
Incorporate industry best practices
Address contemporary software development issues
! scale, distribution, concurrency, executability, etc.
Provide flexibility for applying different processes
Enable model interchange and define repository
interfaces
Behavioral Modeling with UML
6
OMG UML Evolution
2001
(planned major revision)
<<document>>
UML 2.0
<<refine>>
Q3 2000
(planned minor revision)
<<document>>
UML 1.4
<<refine>>
Q3 1999
<<document>>
UML 1.3
Other relevant
standards TBA
<<informalLiaison>>
ISO Publicly
Available
Specifications
(PAS)
<<formalLiaison>>
<<refine>>
Q2 1998
<<document>>
UML 1.2
Editorial revision
with no significant
technical changes.
<<refine>>
Q3 1997
(OMG Adopted
Technology)
<<document>>
UML 1.1
Unification of major
modeling languages,
including Booch, OMT
and Objectory
Behavioral Modeling with UML
7
OMG UML 1.3 Specification
!
!
!
!
UML
UML
UML
UML
!
!
!
!
!
Summary
Semantics
Notation Guide
Standard Profiles
Software Development Processes
Business Modeling
UML CORBAfacility Interface Definition
UML XML Metadata Interchange DTD
Object Constraint Language
Behavioral Modeling with UML
8
Tutorial Focus: the Language
!
language = syntax + semantics
!
!
!
!
syntax = language elements (e.g. words)
are assembled into expressions (e.g.
phrases, clauses)
semantics = the meanings of the syntactic
expressions
UML Notation Guide – defines UML’s
graphic syntax
UML Semantics – defines UML’s
semantics
Behavioral Modeling with UML
9
Unifying Concepts
!
classifier-instance dichotomy
!
!
specification-realization dichotomy
!
!
e.g. an object is an instance of a class OR
a class is the classifier of an object
e.g. an interface is a specification of a class
OR
a class is a realization of an interface
analysis-time vs. design-time vs. runtime
!
!
modeling phases (“process creep”)
usage guidelines suggested, not enforced
Behavioral Modeling with UML
10
Language Architecture
!
!
Metamodel architecture
Package structure
Behavioral Modeling with UML
11
Metamodel Architecture
<<metamodel>>
MOF Metametamodel
Meta-Metamodel Layer
(M3): Specifies metametaclasses for the
UML metamodel
<<metamodel>>
UML Metamodel
Metamodel Layer (M2):
Specifies metaclasses
for the UML
metamodel, such as
Class
Model Layer (M1): Specifies
classes for the UML user
models, such as
Passenger, Ticket,
TravelAgency
User Model
:Foo
:Bar
:Baz
Behavioral Modeling with UML
User Objects Layer (M0):
User objects that are
instances of UML user
model classes, such as
instances of Passenger,
Ticket, TravelAgency
12
Package Structure
<<metamodel>>
UML
Behavioral
Elements
Model
Management
dependency
Foundation
Behavioral Modeling with UML
package
13
Package Structure
Behavioral Elements
Collaborations
Use Cases
State Machines
Activity Graphs
Model
Management
Common
Behavior
Foundation
Behavioral Modeling with UML
14
Behavioral Modeling
!
!
!
Part 1: Interactions and Collaborations
Part 2: Statecharts
Part 3: Activity Diagrams
Behavioral Modeling with UML
15
Interactions
!
!
!
!
!
!
What are interactions?
Core concepts
Diagram tour
When to model interactions
Modeling tips
Example: A Booking System
Behavioral Modeling with UML
16
What are interactions?
!
!
Interaction: a collection of
communications between instances,
including all ways to affect instances,
like operation invocation, as well as
creation and destruction of instances
The communications are partially
ordered (in time)
Behavioral Modeling with UML
17
Interactions: Core Elements
Construct
Description
Instance
(object,
data value,
component
instance
etc.)
An entity with a unique identity and
to which a set of operations can be
applied (signals be sent) and which
has a state that stores the effects of
the operations (the signals).
Action
A specification of an executable
statement.
A few different kinds of actions are
predefined, e.g. CreateAction,
CallAction, DestroyAction, and
UninterpretedAction.
Behavioral Modeling with UML
Syntax
name
attr values
textual
18
Interaction: Core Elements
Construct
Description
Stimulus
A communication between two
instances.
Operation
A declaration of a service that can
be requested from an instance to
effect behavior.
Signal
A specification of an asynchronous
stimulus communicated between
instances.
Behavioral Modeling with UML
(cont’d)
Syntax
textual
«Signal»
Name
parameters
19
Interaction: Core Relationships
Construct
Link
Description
Syntax
A connection between instances.
Attribute Link A named slot in an instance, which
holds the value of an attribute.
Behavioral Modeling with UML
textual
20
Example: Instance
triangle : Polygon
underlined name
triangle : Polygon
center : Point = (2,2)
vertices : Point* = ((0,0), (4, 0), (2,4))
borderColor : Color = black
fillColor : Color = white
attribute links
triangle
: Polygon
Behavioral Modeling with UML
21
Example: Instances and Links
: Family
Joe : Person
husband
wife
Behavioral Modeling with UML
Jill : Person
22
Operation and Method
Triangle
+ move (in dist : Point)
+ scale (in factor : Real)
foreach v in vertices do
v.x := v.x + dist.x;
v.y := v.y + dist.y
foreach v in vertices do
v.x := factor * v.x;
v.y := factor * v.y
Behavioral Modeling with UML
23
Interaction Diagram Tour
!
Show interactions between instances in
the model
!
!
!
!
graph of instances (possibly including links)
and stimuli
existing instances
creation and deletion of instances
Kinds
!
!
sequence diagram (temporal focus)
collaboration diagram (structural focus)
Behavioral Modeling with UML
24
Interaction Diagrams
Sequence Diagram
x
y
Collaboration Diagram
z
1.1: a
1.2: c
x
a
y
b
1.1.1: b
c
z
Behavioral Modeling with UML
25
Sequence Diagram
object symbol
name : Class
other
lifeline
stimulus
name (…)
activation
new (…)
: Class
delete
return
create
Behavioral Modeling with UML
26
Arrow Label
predecessor sequence-expression return-value := message-name argument-list
move (5, 7)
3.7.4: move (5, 7)
A3, B4 / C3.1: res := getLocation (fig)
3.7 *[1..5]: move (5, 7)
predecessor
sequence number
return value
iteration
message name
3.7 [ z > 0 ]: move (5, 7)
Behavioral Modeling with UML
argument list
condition
27
Different Kinds of Arrows
Procedure call or other
kind of nested flow of
control
UML 1.4: Asynchronous
Flat flow of control
Explicit asynchronous
flow of control
UML 1.4: Variant of async
Return
Behavioral Modeling with UML
28
Example: Different Arrows
UML 1.4: Alternative notation
UML 1.4: Asynchronous flow for async flow
Nested Flow
teller
: Order
: Article
Flat Flow
caller
exchange
Asynchronous Flow
callee
appl
err handl
alarm
lift receiver
getValue
unknown
dial tone
price
alarm
dial digit
dial digit
getName
ringing tone
ringing signal
lift receiver
Behavioral Modeling with UML
29
Recursion, Condition, etc.
calculator
filter
value
[ x > 0]: getValue ()
[ x < 0]: transform ()
getValue ()
iterate ()
Behavioral Modeling with UML
30
Collaboration Diagram
object symbol
standard
stereotype
link symbol
redisplay ()
stimulus
window
: Controller
standard
stereotype
1: displayPositions (window)
1.1 *[i := 1..n]: drawSegment (i)
standard
stereotype
1.1.1a: r0 := position ()
left : Bead
window «parameter»
standard
constraint
1.1.3.1 add (self)
wire
contents {new}
«local» line
wire :Wire
«self»
: Window
1.1.2: create (r0, r1)
1.1.3: display (window)
1.1.1b: r1 := position ()
{new}
: Line
standard
constraint
right : Bead
Behavioral Modeling with UML
31
When to Model Interactions
!
!
!
To specify how the instances are to
interact with each other.
To identify the interfaces of the
classifiers.
To distribute the requirements.
Behavioral Modeling with UML
32
Interaction Modeling Tips
!
!
!
!
!
Set the context for the interaction.
Include only those features of the instances
that are relevant.
Express the flow from left to right and from
top to bottom.
Put active instances to the left/top and
passive ones to the right/bottom.
Use sequence diagrams
!
!
!
to show the explicit ordering between the stimuli
when modeling real-time
Use collaboration diagrams
!
!
when structure is important
to concentrate on the effects on the instances
Behavioral Modeling with UML
33
Example: A Booking System
Behavioral Modeling with UML
34
Use Case Description: Change Flt Itinerary
!
!
!
Actors: traveler, client account db, airline
reservation system
Preconditions: Traveler has logged in
Basic course:
!
!
!
!
!
!
!
!
Traveler selects ‘change flight itinerary’ option
System retrieves traveler’s account and flight itinerary from client account
database
System asks traveler to select itinerary segment she wants to change;
traveler selects itinerary segment.
System asks traveler for new departure and destination information;
traveler provides information.
If flights are available then …
…
System displays transaction summary.
Alternative course:
!
If no flights are available then…
Behavioral Modeling with UML
35
Sequence Diagram: Change Flight Itinerary
Traveler
: Booking System
Client Account DBMS
Airline Reservation System
change flight itinerary
get customer account
get itinerary
present itinerary
select segment
present detailed info
update information
available flight
:
:
Behavioral Modeling with UML
36
Collaboration Diagram: Change Flt Itinerary
1: change flight itinerary
5: select segment
7: update information
2: get customer account
3: get itinerary
: Booking System
4: present itinerary
Traveler 6: present detailed info
Client Account DBMS
8: available flight
Airline Reservation System
Behavioral Modeling with UML
37
Collaboration
!
!
!
!
!
!
What is a collaboration?
Core concepts
Diagram tour
When to model collaborations
Modeling tips
Example: A Booking System
Behavioral Modeling with UML
38
What is a collaboration?
!
!
Collaboration: a collaboration defines
the roles a set of instances play when
performing a particular task, like an
operation or a use case.
Interaction:an interaction specifies a
communication pattern to be performed
by instances playing the roles of a
collaboration.
Behavioral Modeling with UML
39
Collaborations: Core Elements
Construct
Collaboration
Interaction
Description
A collaboration describes how an
operation or a classifier, like a
use case, is realized by a set of
classifiers and associations used
in a specific way.
The collaboration defines a set of
roles to be played by instances
and links, possibly including a
collection of interactions.
Syntax
Name
An interaction describes a
communication pattern between
instances when they play the
roles of the collaboration.
Behavioral Modeling with UML
40
Collaborations: Core Elements
Construct
Description
Collaboration- A collection of instances which
together play the roles declared
Instance
in a collaboration.
InteractionInstance
(cont’d)
Syntax
Name
A collection of stimuli
exchanged between instances
playing specific roles according
to the communication pattern of
an interaction.
All new in UML 1.4
Behavioral Modeling with UML
41
Collaborations: Core Elements
Construct
Description
Classifier
Role
A classifier role is a specific role
played by a participant in a
collaboration. It specifies a restricted
view of a classifier, defined by what
is required in the collaboration.
Message
A message specifies one
communication between instances.
It is a part of the communication
pattern given by an interaction.
Behavioral Modeling with UML
(cont’d)
Syntax
/ Name
label
42
Collaborations: Core Relationships
Construct
Description
Association
Role
An association role is a specific
usage of an association needed
in a collaboration.
Generalization
A generalization is a taxonomic
relationship between a more
general element and a more
specific element. The more
specific element is fully consistent
with the more general element.
Behavioral Modeling with UML
Syntax
43
Classifier-Instance-Role Trichotomy
!
!
!
An Instance is an
entity with behavior
and a state, and has
a unqiue identity.
A Classifier is a
description of an
Instance.
A Classifier Role
defines a usage (an
abstraction) of an
Instance.
id
«originates from»
ClassName
«conforms to»
/ RoleName
Behavioral Modeling with UML
«view of»
44
Classifier-Instance-Role Trichotomy (cont’d)
Classifier
Attribute-1
Attribute-2
Attribute-3
Operation-1 (…)
Operation-2 (…)
Operation-3 (…)
ClassifierRole
Attribute-1
Attribute-2
«originates from»
«conforms to»
Operation-1 (…)
Operation-3 (…)
Instance
AttributeValue-1
AttributeValue-2
AttributeValue-3
•The attribute values of an Instance corresponds to the attributes of its
Classifier.
•All attributes required by the ClassifierRole have corresponding attribute
values in the Instance.
•All operations defined in the Instance’s Classifier can be applied to the
Instance.
•All operations required by the ClassifierRole are applicable to the Instance.
Behavioral Modeling with UML
45
Different Ways to Name a Role
/ ClassifierRoleName : ClassifierName
A role name is preceeded by a ‘/’
Example:
A classifier name is preceeded by a ‘:’
/ Parent : Person
/ Parent
: Person
instanceName / ClassifierRoleName : ClassifierName
Example:
: Person
Charlie
Charlie / Parent
Charlie : Person
Charlie / Parent : Person
Behavioral Modeling with UML
46
Association and Association Role
Class
Class-1
Association
Class
0..5
{changeable}
Class-2
«view of»
«view of»
/ Role-1
{frozen}
ClassifierRole
«view of»
3..4
/ Role-2
AssociationRole ClassifierRole
•An Association Role specifies the required
properties of a Link used in a
Collaboration.
•The properties of an AssociationEnd may
be restricted by a AssociationEndRole.
Behavioral Modeling with UML
47
Example: A School
/ Teacher : Person
1 tutor
student *
/ Student : Person
program : Text
position : Text
faculty member *
faculty 1
1 lecturer
participant *
given course *
: Faculty
taken course *
: Course
Behavioral Modeling with UML
48
Role Model vs. Class Model
The Classes give the complete description while the
Roles specify one usage.
Role Model
Class Model
Extra attribute
/ Teacher : Person 1
position : Text
*
1
: Faculty
* / Student : Person
Person
Resulting multiplicity
program : Text
*
*
1
*
*
: Course
0..1
Faculty
Behavioral Modeling with UML
Resulting multiplicity
0..1
name : Text
position : Text
program : Text
1
*
*
*
*
Course
49
A Collaboration and Its Roles
A Collaboration
and how its roles
are mapped onto
a collection of
Classifiers and
Associations.
CollaborationName
roleName-1
roleName-2
Classifier-1
Behavioral Modeling with UML
roleName-3
Classifier-2
50
Patterns in UML
Constraint that must
be fulfilled in each instance
of this pattern.
Handler.reading = length (Subject.queue)
Handler.range = {0..Subject.capacity}
Observer
Subject
Handler
CallQueue
SlidingBarIcon
queue : List of Call
source : Object
waitAlarm : Alarm
capacity : Integer
reading : Real
color : Color
range : Interval
Behavioral Modeling with UML
51
Generalization Between Collaborations
Subject
CallQueue
Handler
Subject
ManagedQueue
SlidingBarIcon
Observer
Supervisor
Manager
Controller
•All roles defined in the parent are present
in the child.
•Some of the parent’s roles may be
overridden in the child.
•An overridden role is usually the parent of
the new role.
Behavioral Modeling with UML
52
Collaboration Diagram Tour
!
!
Show Classifier Roles and Association
Roles, possibly together with extra
constraining elements
Kinds
!
!
!
Instance level – Instances and Links
Specification level – Roles
Static Diagrams are used for showing
Collaborations explicitly
Behavioral Modeling with UML
53
Collaboration Diagram at Specification Level
/ Teacher : Person 1 tutor
position : Text
faculty member *
faculty 1
: Faculty
student * / Student : Person
program : Text
* participant
1 lecturer
given course *
* taken course
: Course
UML 1.4: The diagram shows the contents of a Collaboration
Behavioral Modeling with UML
54
Collaboration Diagram at Instance Level
student
tutor
faculty member
Alice / Student
John / Teacher
tutor
faculty
student
participant
Bob / Student
participant
: Faculty
taken course
faculty
Sara / Teacher
lecturer
given course
taken course
English : Course
faculty member
UML 1.4: The diagram shows the contents of a
CollaborationInstance
Behavioral Modeling with UML
55
Collaborations including Interactions
Sequence Diagram
x
y
Collaboration Diagram
z
1.1: a
1.2: c
x
a
y
b
1.1.1: b
c
z
UML 1.4: The diagrams show the contents
of a CollaborationInstance with an
InteractionInstance superposed
Behavioral Modeling with UML
56
Roles on Sequence Diagrams
Sequence Diagram
/X
/Y
/Z
a
b
c
UML 1.4: The diagram shows the contents of a
Collaboration with an Interaction superposed
Behavioral Modeling with UML
57
Collaboration Diagram with Constraining Elements
/ Generator
: Printer Device
Constraining Element
(A Generalization is not
an AssociationRole )
: Laser Printer
: Line Printer
Behavioral Modeling with UML
58
Static Diagram With Collaboration and Classifiers
Subject
CallQueue
Handler
Subject
ManagedQueue
SlidingBarIcon
Observer
Supervisor
Manager
Behavioral Modeling with UML
Controller
59
When to Model Collaborations
!
!
!
Use Collaborations as a tool to find the
Classifiers.
Trace a Use Case / Operation onto
Classifiers.
Map the specification of a Subsystem
onto its realization (Tutorial 3).
Behavioral Modeling with UML
60
Collaboration Modeling Tips
!
!
!
A collaboration should consist of both
structure and behavior relevant for the
task.
A role is an abstraction of an instance,
it is not a class.
Look for
!
!
!
initiators (external)
handlers (active)
managed entities (passive)
Behavioral Modeling with UML
61
Example: A Booking System
Behavioral Modeling with UML
62
Use Case Description: Change Flt Itinerary
!
!
!
Actors: traveler, client account db, airline
reservation system
Preconditions: Traveler has logged in
Basic course:
!
!
!
!
!
!
!
!
Traveler selects ‘change flight itinerary’ option
System retrieves traveler’s account and flight itinerary from client account
database
System asks traveler to select itinerary segment she wants to change;
traveler selects itinerary segment.
System asks traveler for new departure and destination information;
traveler provides information.
If flights are available then …
…
System displays transaction summary.
Alternative course:
!
If no flights are available then…
Behavioral Modeling with UML
63
Booking System: Change Flt Itinerary Collaboration
4: get customer account
7: get itinerary
1: change flight itinerary
: Traveler
/ Flight Itenerary Form
10: present
2: create modifier
/ DBMS Protocol
9: display
/ Flight Itinerary Modifier
5: create
/ Account
: Client Account DBMS
3: get customer account
6: get itinerary
8: create
/ Itinerary
/ ARS Protocol
: Airline Reservation System
Behavioral Modeling with UML
64
Wrap Up: Interactions & Collaborations
!
!
Instances, Links and Stimuli are used
for expressing the dynamics in a model.
Collaboration is a tool for
!
!
!
!
identification of classifiers
specification of the usage of instances
expressing a mapping between different
levels of abstraction
Different kinds of diagrams focus on
time or on structure
Behavioral Modeling with UML
65
Behavioral Modeling
!
!
!
Part 1: Interactions and Collaborations
Part 2: Statecharts
Part 3: Activity Diagrams
Behavioral Modeling with UML
66
Overview
!
!
!
!
!
Basic State Machine Concepts
Statecharts and Objects
Advanced Modeling Concepts
Case Study
Wrap Up
Behavioral Modeling with UML
67
Automata
!
!
A machine whose output behavior is not only
a direct consequence of the current input, but
of some past history of its inputs
Characterized by an internal state which
represents this past experience
ON
ON ON
ON
OFF
OFF
Behavioral Modeling with UML
68
State Machine (Automaton) Diagram
!
Graphical rendering of automata
behavior
on
Lamp On
on
off
off
Lamp Off
Behavioral Modeling with UML
69
Outputs and Actions
!
As the automaton changes state it can
generate outputs:
on
on
Lamp On
print(”on”)
Lamp
On
on
on/print(”on”)
off
off
Lamp
Off
off
Mealy automaton
Lamp
Off
off
Moore automaton
Behavioral Modeling with UML
70
Extended State Machines
!
Addition of variables (“extended state”)
on
ctr
ctr :: Integer
Integer
Lamp On
on/ctr := ctr + 1
off
off
Lamp Off
Behavioral Modeling with UML
71
A Bit of Theory
!
An extended (Mealy) state machine is defined
by:
!
!
!
!
a
a
a
a
set
set
set
set
!
!
!
!
!
of
of
of
of
input signals (input alphabet)
output signals (output alphabet)
states
transitions
triggering signal
action
a set of extended state variables
an initial state designation
a set of final states (if terminating automaton)
Behavioral Modeling with UML
72
Basic UML Statechart Diagram
“top”
“top” state
state
Initial
Initial
pseudostate
pseudostate
State
State
top
Trigger
Trigger
Ready
Transition
Transition
stop /ctr := 0
Final
Final
state
state
Done
Action
Action
stop
Behavioral Modeling with UML
73
What Kind of Behavior?
!
In general, state machines are suitable
for describing event-driven, discrete
behavior
!
inappropriate for modeling continuous
behavior
threshold
time
Behavioral Modeling with UML
74
Event-Driven Behavior
!
Event = a type of observable occurrence
!
interactions:
!
!
!
occurrence of time instants (time event)
!
!
!
!
synchronous object operation invocation (call event)
asynchronous signal reception (signal event)
interval expiry
calendar/clock time
change in value of some entity (change event)
Event Instance = an instance of an event
(type)
!
occurs at a particular time instant and has no
duration
Behavioral Modeling with UML
75
The Behavior of What?
!
In principle, anything that manifests
event-driven behavior
!
!
In practice:
!
!
!
NB: there is no support currently in UML
for modeling continuous behavior
the behavior of individual objects
object interactions
The dynamic semantics of UML state
machines are currently mainly specified
for the case of active objects
Behavioral Modeling with UML
76
Basic State Machine Concepts
Statecharts and Objects
Advanced Modeling Concepts
Case Study
Wrap Up
Behavioral Modeling with UML
77
Object Behavior - General Model
!
Simple server model:
Handling
Handling depends
depends on
on
specific
specific request
request type
type
Initialize
Initialize
Object
Object
Wait
Waitfor
for
Request
Request
void:offHook ();
{busy = true;
obj.reqDialtone();
…
};
Handle
Handle
Request
Request
Terminate
Terminate
Object
Object
Behavioral Modeling with UML
78
Object Behavior and State Machines
!
Direct mapping:
on
Initialize
Object
Lamp
On
Wait for
Event
Handle
Event
on/print(”on”)
off
Lamp
Off
Terminate
Object
off
stop
Behavioral Modeling with UML
79
Object and Threads
•Passive objects: depend on external power (thread
of execution)
•Active objects: self-powered (own thread of
execution)
Initialize
Initialize
Object
Object
Initialize
Initialize
Object
Object
Wait
Waitfor
for
Request
Request
Wait
Waitfor
for
Request
Request
Handle
Handle
Request
Request
Handle
Handle
Request
Request
Terminate
Terminate
Object
Object
Terminate
Terminate
Object
Object
Behavioral Modeling with UML
80
Passive Objects: Dynamic Semantics
Initialize
Initialize
Object
Object
Wait
Waitfor
for
Request
Request
Handle
Handle
Request
Request
Terminate
Terminate
Object
Object
•Encapsulation does not protect the object from
concurrency conflicts!
•Explicit synchronization is still required
Behavioral Modeling with UML
81
Active Objects and State Machines
!
Objects that encapsulate own thread of
execution
anActiveObject
#currentEvent : Eventpoll/defer
created
start
+ start ( )
+ poll ( )
+ stop ( )
start/^master.ready()
ready
ready
stop/
poll/^master.ack()
Behavioral Modeling with UML
82
Active Objects: Dynamic Semantics
ActiveObject:
Run-to-completion model:
•serialized event handling
•eliminates internal concurrency
•minimal context switching overhead
Behavioral Modeling with UML
83
The Run-to-Completion Model
!
A high priority event for (another) active
object will preempt an active object that is
handling a low-priority event
Active1
Active1
Active2
Active2
lo
hi
hi
Behavioral Modeling with UML
84
Basic State Machine Concepts
Statecharts and Objects
Advanced Modeling Concepts
Case Study
Wrap Up
Behavioral Modeling with UML
85
State Entry and Exit Actions
!
A dynamic assertion mechanism
LampOn
entry/lamp.on();
e2
exit/lamp.off();
e1
Behavioral Modeling with UML
86
Order of Actions: Simple Case
!
!
Exit actions prefix transition actions
Entry action postfix transition actions
LampOn
entry/lamp.on();
LampOff
off/printf(“to off”);
entry/lamp.off();
exit/printf(“exiting”);
exit/printf(“exiting”);
Resulting action sequence:
printf
(“exiting”);
printf(“exiting”);
printf
(“to off”);
printf(“to
lamp.off();
off/printf(“needless”);
printf
(“exiting”);
printf(“exiting”);
printf
(“needless”);
printf(“needless”);
lamp.off();
Behavioral Modeling with UML
87
Internal Transitions
!
Self-transitions that bypass entry and
exit actions
Internal transition
triggered by
an “off” event
LampOff
entry/lamp.off();
exit/printf(“exiting”);
off/null;
Behavioral Modeling with UML
88
State (“Do”) Activities
!
Forks a concurrent thread that executes
until:
!
!
the action completes or
the state is exited through an outgoing
transition
“do” activity
Error
entry/printf(“error!”)
do/while (true) alarm.ring();
Behavioral Modeling with UML
89
Guards
!
Conditional execution of transitions
!
guards (Boolean predicates) must be side-effect free
bid [value < 100] /reject
bid [value >= 200] /sell
Selling
Happy
bid [(value >= 100) & (value < 200)] /sell
Unhappy
Behavioral Modeling with UML
90
Static Conditional Branching
!
Merely a graphical shortcut for
convenient rendering of decision trees
Selling
Happy
bid
[value >= 200] /sell
[value < 100] /reject
[(value >= 100) & (value < 200)] /sell
Unhappy
Behavioral Modeling with UML
91
Dynamic Conditional Branching
!
Choice pseudostate: guards are evaluated at
the instant when the decision point is reached
Selling
Happy
bid /gain := calculatePotentialGain(value)
[gain >= 200] /sell
[gain < 100] /reject
[(gain >= 100) & (gain < 200)] /sell
Dynamic
Dynamic
choicepoint
choicepoint
Unhappy
Behavioral Modeling with UML
92
Hierarchical State Machines
!
Graduated attack on complexity
!
states decomposed into state machines
LampOff
LampOff
entry/lamp.off()
flash/
LampFlashing
FlashOn
FlashOn
entry/lamp.on()
off/
1sec/
on/
LampOn
LampOn
1sec/
on/
on/
FlashOff
FlashOff
entry/lamp.off()
entry/lamp.on()
Behavioral Modeling with UML
93
“Stub” Notation
!
Notational shortcut: no semantic
significance
LampOff
LampOff
entry/lamp.off()
flash/
LampFlashing
FlashOn
off/
on/
LampOn
LampOn
on/
on/
FlashOff
entry/lamp.on()
Behavioral Modeling with UML
94
Group Transitions
!
Default
Default transition
transition to
to
Higher-level transitions
the
the initial
initial pseudostate
pseudostate
LampOff
LampOff
entry/lamp.off()
LampFlashing
flash/
FlashOn
FlashOn
entry/lamp.on()
off/
1sec/
1sec/
on/
LampOn
LampOn
on/
FlashOff
FlashOff
entry/lamp.off()
entry/lamp.on()
Group
Group transition
transition
Behavioral Modeling with UML
95
Completion Transitions
!
Triggered by a completion event
!
generated automatically when an immediately
nested state machine terminates
Committing
completion
transition (no trigger)
Phase1
Phase1
CommitDone
Phase2
Phase2
Behavioral Modeling with UML
96
Triggering Rules
!
Two or more transitions may have the same
event trigger
!
!
innermost transition takes precedence
event is discarded whether or not it triggers a
transition
LampFlashing
FlashOn
FlashOn
on/
on/
off/
FlashOff
FlashOff
Behavioral Modeling with UML
97
Deferred Events
!
Events can be retained if they do not
trigger a transition
LampOff
LampOff
Deferred
Deferred event
event
entry/lamp.off()
off/defer
off/
on/
LampOn
LampOn
entry/lamp.on()
Behavioral Modeling with UML
98
Order of Actions: Complex Case
!
Same approach as for the simple case
S1
exit/exS1
S2
entry/enS2
initS2
S11
exit/exS11
E/actE
S21
entry/enS21
Actions execution sequence:
exS11 " exS1 " actE " enS2 " initS2 " enS21
Behavioral Modeling with UML
99
History
!
Return to a previously visited hierarchical
state
!
deep and shallow history options
Diagnosing
suspend/
resume/
H*
H*
Diagnostic1
Diagnostic1
Diagnostic2
Diagnostic2
Step11
Step11
Step21
Step21
Step12
Step12
Step22
Step22
Behavioral Modeling with UML
100
Orthogonality
!
age
Multiple simultaneous perspectives on the
same entity
financialStatus
Child
Poor
Adult
Rich
Retiree
Behavioral Modeling with UML
101
Orthogonal Regions
!
Combine multiple simultaneous descriptions
age
financialStatus
Child
Poor
Adult
Retiree
age
financialStatus
Rich
Child
Poor
Adult
Retiree
Rich
Behavioral Modeling with UML
102
Orthogonal Regions - Semantics
!
All mutually orthogonal regions detect the
same events and respond to them
“simultaneously”
!
usually reduces to interleaving of some kind
legalStatus
LawAbiding
LawAbiding
robBank/
Outlaw
Outlaw
financialStatus
Poor
Poor
robBank/
Rich
Rich
Behavioral Modeling with UML
103
Interactions Between Regions
!
Typically through shared variables or
awareness of other regions’ state changes
sane
sane :: Boolean
Boolean
flying
flying :: Boolean
Boolean
Catch22
Catch22
sanityStatus
flightStatus
Crazy
Crazy
Flying
Flying
entry/sane
entry/sane :=
:= false;
false;
entry/flying
entry/flying :=
:= true;
true;
(flying)/
request
Grounding/
(sane)/
(~sane)/
Sane
Sane
Grounded
Grounded
entry/sane
entry/sane :=
:= true;
true;
entry/flying
entry/flying :=
:= false;
false;
Behavioral Modeling with UML
104
Transition Forks and Joins
!
For transitions into/out of orthogonal
regions:
age
Child
Child
Staff
Staff
Member
Member
Adult
Adult
Retiree
Retiree
Manager
Manager
employee
Behavioral Modeling with UML
105
Common Misuse of Orthogonality
!
Using regions to model independent objects
Person1
Person2
Person1
Person2
Child
Child
Adult
Adult
Retiree
Retiree
Behavioral Modeling with UML
106
Basic State Machine Concepts
Statecharts and Objects
Advanced Modeling Concepts
Case Study
Wrap Up
Behavioral Modeling with UML
107
Case Study: Protocol Handler
!
A multi-line packet switch that uses the
alternating-bit protocol as its link
protocol
AB
AB protocol
protocol
End user
AB
sender
line card 1
End user
.
.
.
unreliable
telecom lines
AB
sender
AB
receiver
End user
AB
receiver
SWITCH
line card N
Behavioral Modeling with UML
108
Alternating Bit Protocol (1)
!
A simple one-way point-to-point packet
protocol
AB
AB protocol
protocol
packetizer
Sender
Receiver
unpacker
data(1)
pktA
data(1)
ack
ackA
ack
data(2)
pktB
data(2)
ack
ackB
ack
…etc.
Behavioral Modeling with UML
109
Alternating Bit Protocol (2)
!
State machine specification
Receiver SM
Sender SM
AcceptPktA
RcvdPktA
ackB/^ack
data/^pktA
pktA/^data
ack/^ackA
timeout/^pktB
WaitAckA
timeout/^ackB
WaitAckB
WaitPktA
timeout/^ackA
timeout/^pktA
ackA/^ack
WaitPktB
data/^pktB
pktB/^data
AcceptPktB
ack/^ackB
RcvdPktB
Behavioral Modeling with UML
110
Additional Considerations
!
Support (control) infrastructure
operator
interface
AB
receiver
System
operator
AB lines
manager
AB
sender
SWITCH
DB
interface
DBase
Behavioral Modeling with UML
111
Control
The set of (additional) mechanisms and
actions required to bring a system into the
desired operational state and to maintain it in
that state in the face of various planned and
unplanned disruptions
For software systems this includes:
•system/component start-up and shut-down
•failure detection/reporting/recovery
•system administration, maintenance, and
provisioning
•(on-line) software upgrade
Behavioral Modeling with UML
112
Retrofitting Control Behavior
Hardware
Audit
JustCreated
Analysing
Failure
ReadyToGo
GettingData
AcceptPktA
WaitAckA
Failed
WaitAckB
AcceptPktB
Behavioral Modeling with UML
113
The Control Automaton
!
In isolation, the same control behavior
appears much simpler
JustCreated
GettingData
Hardware
Audit
ReadyToGo
Analysing
Failure
Failed
Operational
Behavioral Modeling with UML
114
Exploiting Inheritance
!
Abstract control classes can capture the
common control behavior
AbstractController
Sender
Receiver
. . .
Behavioral Modeling with UML
115
Exploiting Hierarchical States
JustCreated
Analysing
Failure
AbstractController
GettingData
Failed
Hardware
Audit
ReadyToGo
Sender
Operational
Behavioral Modeling with UML
116
Basic State Machine Concepts
Statecharts and Objects
Advanced Modeling Concepts
Case Study
Wrap Up
Behavioral Modeling with UML
117
Wrap Up: Statecharts
!
UML uses an object-oriented variant of
Harel’s statecharts
!
!
Used to model event-driven (reactive)
behavior
!
!
adjusted to software modeling needs
well-suited to the server model inherent in the
object paradigm
Primary use for modeling the behavior of
active event-driven objects
!
!
systems modeled as networks of collaborating
state machines
run-to-completion paradigm significantly simplifies
concurrency management
Behavioral Modeling with UML
118
Wrap Up: Statecharts (cont’d)
!
Includes a number of sophisticated features
that realize common state-machine usage
patterns:
!
!
!
!
entry/exit actions
state activities
dynamic and static conditional branching
Also, provides hierarchical modeling for
dealing with very complex systems
!
!
!
hierarchical states
hierarchical transitions
orthogonality
Behavioral Modeling with UML
119
Behavioral Modeling
!
!
!
Part 1: Interactions and Collaborations
Part 2: Statecharts
Part 3: Activity Diagrams
Behavioral Modeling with UML
120
Activity Diagram Applications
!
!
!
!
Intended for applications that need control
flow or object/data flow models …
... rather than event-driven models like state
machines.
For example: business process modeling and
workflow.
The difference in the three models is how
step in a process is initiated, especially with
respect to how the step gets its inputs.
Behavioral Modeling with UML
121
Control Flow
!
!
!
Each step is taken when the previous one
finishes …
…regardless of whether inputs are available,
accurate, or complete (“pull”).
Emphasis is on order in which steps are
taken.
Weather Info
Start
Analyze
AnalyzeWeather
WeatherInfo
Info
Not UML
Notation!
Chart
ChartCourse
Course
Cancel
CancelTrip
Trip
Behavioral Modeling with UML
122
Object/Data Flow
!
!
!
Each step is taken when all the required input
objects/data are available …
… and only when all the inputs are available
(“push”).
Emphasis is on objects flowing between steps.
Design
DesignProduct
Product
Acquire
AcquireCapital
Capital
Procure
Procure
Materials
Materials
Build
Build
Subassembly
Subassembly22
Build
Build
Subassembly
Subassembly11
Not UML
Notation
Final
Final
Assembly
Assembly
Behavioral Modeling with UML
123
State Machine
!
!
!
Each step is taken when events are
detected by the machine …
… using inputs given by the event.
Emphasis is on reacting to environment.
Ready
ReadyTo
ToStart
Start
Coin
Deposited
Ready
ReadyFor
ForOrder
Order
Selection
Made
Cancel Button
Pressed
Dispense
Dispense
Product
Product
Return
Return
Change
Change
Not UML
Notation
Behavioral Modeling with UML
124
Activity Diagrams Based on State Machines
!
!
!
!
Currently activity graphs are modeled
as a kind of state machine.
Modeler doesn't normally need to be
aware of this sleight-of-hand ...
... but will notice that "state" is used in
the element names.
Activity graphs will become independent
of state machines in UML 2.0.
Behavioral Modeling with UML
125
Kinds of Steps in Activity Diagrams
!
Action (State)
!
Subactivity (State)
!
!
!
Action
Subactivity
Just like their state machine counterparts
(simple state and submachine state) except
that ...
... transitions coming out of them are taken
when the step is finished, rather than being
triggered by a external event, ...
... and they support dynamic concurrency.
Behavioral Modeling with UML
126
Action (State)
Action
!
!
An action is used for anything that does not
directly start another activity graph, like
invoking an operation on an object, or
running a user-specified action.
However, an action can invoke an operation
that has another activity graph as a method
(possible polymorphism).
Behavioral Modeling with UML
127
Subactivity (State)
Subactivity
!
!
!
A subactivity (state) starts another activity
graph without using an operation.
Used for functional decomposition, nonpolymorphic applications, like many workflow
systems.
The invoked activity graph can be used by
many subactivity states.
Behavioral Modeling with UML
128
Example
POEmployee.sortMail
Deliver Mail
Deliver Mail
POEmployee
sortMail()
Check Out
Truck
Behavioral Modeling with UML
Put Mail
In Boxes
129
Activity Graph as Method
POEmployee.sortMail
POEmployee.deliverMail
POEmployee
PO Employee Deliver Mail Method
sortMail()
deliverMail()
!
!
«realize»
Check Out
Truck
Put Mail
In Boxes
Application is completely OO when all action states
invoke operations
All activity graphs are methods for operations.
Behavioral Modeling with UML
130
Dynamic concurrency
Action/Subactivity
!
Applies to actions and subactivities.
!
Not inherited from state machines.
!
!
!
!
*
Invokes an action or subactivity any number of times in parallel,
as determined by an expression evaluated at runtime.
Expression also determines arguments.
Upper right-hand corner shows a multiplicity restricting the
number of parallel invocations.
Outgoing transition triggered when all invocations are done.
Currently no standard notation for concurrency expression or
how arguments are accessed by actions. Attach a note as
workaround for expression. Issue for UML 2.0.
Behavioral Modeling with UML
131
Object Flow (State)
Class
[State]
!
!
!
A special sort of step (state) that represents
the availability of a particular kind of object,
perhaps in a particular state.
No action or subactivity is invoked and
control passes immediately to the next step
(state).
Places constraints on input and output
parameters of steps before and after it.
Behavioral Modeling with UML
132
Object Flow (State)
Take Order
!
!
!
Order
[Taken]
Fill Order
Take Order must have an output parameter
giving an order, or one of its subtypes.
Fill Order must have an input parameter
taking an order, or one of its supertypes.
Dashed lines used with object flow have the
same semantics as any other state transition.
Behavioral Modeling with UML
133
Coordinating Steps
!
Inherited from state machines
!
Initial state
!
Final state
!
Fork and join
Behavioral Modeling with UML
134
Coordinating Steps
!
!
Decision point and merge ( ) are
inherited from state machines.
For modeling conventional flow chart
decisions.
Calculate
Cost
[cost < $50]
Charge
Account
[cost >= $50]
Get
Authorization
Behavioral Modeling with UML
135
Coordinating Steps
!
!
State machine
notation
Synch state ( ) is inherited from state
machines but used mostly in activity graphs.
Provides communication capability between
parallel processes.
Put
On
Roof
Build
Frame
Install
Foundation
Install
Walls
Inspect
*
*
Install
Electricity
in Foundation
Install
Electricity
In Frame
Behavioral Modeling with UML
Install
Electricity
Outside
136
Convenience Features (Synch State)
!
!
Activity diagram
notation
Forks and joins do not require composite
states.
Synch states may be omitted for the common
case (unlimited bound and one incoming and
outgoing transition).
Build
Frame
Put
On
Roof
Install
Walls
Install
Foundation
Inspect
Install
Electricity
in Foundation
Install
Electricity
In Frame
Behavioral Modeling with UML
Install
Electricity
Outside
137
Convenience Features (Synch State)
!
Object flow states can be synch states
A11
A12
A13
Obj
[S2]
A21
A22
Behavioral Modeling with UML
A23
138
Convenience Features
!
Fork transitions can have guards.
[ priority = 1]
Evaluate
Impact
Revise
Plan
Register
Bug
Release
Fix
Fix
Bug
!
Test
Fix
Instead of doing this:
[ priority = 1]
Register
Bug
Evaluate
Impact
Revise
Plan
Release
Fix
[else]
Fix
Bug
Test
Fix
Behavioral Modeling with UML
139
Convenience Features
!
!
!
!
Partitions are a grouping mechanism.
Swimlanes are the notation for partitions.
They do not provide domain-specific semantics.
Tools can generate swimlane presentation from
domain-specific information without partitions.
Management
Evaluate
Impact
Revise
Plan
[ priority = 1]
Support
Register
Bug
Release
Fix
Engineering
Fix
Bug
Test
Fix
Behavioral Modeling with UML
140
Convenience Features
!
Signal send icon
Wake Up
Signal
!
!
… translates to a transition
with a send action.
Signal receipt icon
Turn on Coffee Pot
Get Cups
Coffee
Pot
Signal
!
… translates to a wait state (a
state with no action and a
signal trigger event).
Behavioral Modeling with UML
Coffee Done
Drink Coffee
141
partition
Submission Team
action state
Task Force
Revision Task Force
initial state
control flow
Begin
Adapted from
Kobryn, “UML 2001”
Communications of the ACM
October 1999
Case Study
fork of control
Develop
technology
specification
conditional
fork
Issue RFP
RFP
[issued]
join of control
Submit
specification
draft
[optional]
Collaborate with
competitive
submitters
object flow
Specification
[initial
proposal]
input value
Evaluate initial
submissions
Finalize
specification
Specification
[final
proposal]
Behavioral Modeling with UML
142
Collaborate with
competitive
submitters
Evaluate initial
submissions
Finalize
specification
Case Study
Specification
[final
proposal]
Evaluate final
submissions
Vote to
recommend
guard
Specification
[adopted]
[YES]
[NO]
decision
Revise
specification
Adapted from
Kobryn, “UML 2001”
Communications of the ACM
October 1999
Implement
specification
Specification
[revised]
Enhance
specification
[else]
Recommend
revision
[Enhanced]
Behavioral Modeling with UML
final state
143
When to Use Activity Diagrams
!
Use activity diagrams when the
behavior you are modeling ...
!
!
!
!
does not depend much on external events.
mostly has steps that run to completion,
rather than being interrupted by events.
requires object/data flow between steps.
is being constructed at a stage when you
are more concerned with which activities
happen, rather than which objects are
responsible for them (except partitions
possibly).
Behavioral Modeling with UML
144
Activity Diagram Modeling Tips
!
!
!
Control flow and object flow are not
separate. Both are modeled with state
transitions.
Dashed object flow lines are also
control flow.
You can mix state machine and
control/object flow constructs on the
same diagram (though you probably do
not want to).
Behavioral Modeling with UML
145
Activity Diagram Modeling Tips
From UML
User Guide:
Customer
Telesales
Accounting
Warehouse
Request
Return
Get Return
Number
Ship Item
Receive
Item
Item
[returned]
Restock
Item
Credit
Account
Behavioral Modeling with UML
Item
[available]
146
Customer
Telesales
Accounting
Warehouse
Request
Return
Get Return
Number
Activity Modeling Tips
Ship Item
Receive
Item
Item
[returned]
Restock
Item
Credit
Account
Behavioral Modeling with UML
Item
[available]
147
Activity Diagram Modeling Tips
!
!
!
!
Activity diagrams inherit from state machines the
requirement for well-structured nesting of composite
states.
This means you should either model as if composite
states were there by matching all forks/decisions with
a correspond join/merges …
… or check that the diagram can be translated to one
that is well-nested.
This insures that diagram is executable under state
machine semantics.
Behavioral Modeling with UML
148
Activity Diagram Modeling Tips
Well-nested:
Behavioral Modeling with UML
149
Activity Diagram Modeling Tips
Not well-nested:
Apply structured coding principles. (Be careful with goto’s!)
Behavioral Modeling with UML
150
Activity Diagram Modeling Tips
Can be translated to well-nested
diagram on earlier slide:
Behavioral Modeling with UML
151
Wrap Up: Activity Diagrams
!
!
!
!
!
Use Activity Diagrams for applications that are
primarily control and data-driven, like business
modeling …
… rather than event-driven applications like
embedded systems.
Activity diagrams are a kind of state machine until
UML 2.0 …
… so control and object/data flow do not have
separate semantics.
UML 1.3 has new features for business modeling that
increase power and convenience. Check it out and
give feedback!
Behavioral Modeling with UML
152
Preview - Next Tutorial
!
Advanced Modeling with UML
!
!
!
Model management
Standard elements and profiles
Object Constraint Language (OCL)
Behavioral Modeling with UML
153
References
!
!
[UML 1.3] OMG UML Specification v. 1.3,
OMG doc# ad/06-08-99
[UML 1.4] OMG UML Specification v. 1.4, UML
Revision Task Force recommended final draft,
OMG doc# ad/01-02-13.
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Further Info
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Web:
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UML 1.4 RTF: www.celigent.com/omg/umlrtf
OMG UML Tutorials: www.celigent.com/omg/umlrtf/tutorials.htm
UML 2.0 Working Group:
www.celigent.com/omg/adptf/wgs/uml2wg.htm
OMG UML Resources: www.omg.org/uml/
Email
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[email protected]
Contributors:
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Gunnar Övergaard: [email protected]
Bran Selic: [email protected]
Conrad Bock: [email protected]
Morgan Björkander: [email protected]
Conferences & workshops
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UML World 2001, New York, June 11-14, 2001
UML 2001, Toronto, Canada, Oct. 1-5, 2001
OMG UML Workshop 2001, San Francisco, Dec. 3-6, 2001
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