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Object Modeling with UML: Behavioral Modeling
 

Object Modeling with UML: Behavioral Modeling

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    Object Modeling with UML: Behavioral Modeling Object Modeling with UML: Behavioral Modeling Presentation Transcript

    • Object Modeling with UML: Behavioral Modeling Gunnar Övergaard, Bran Selic and Conrad Bock January 2000 © 1999 OMG and Tutorial Contributors: EDS, IBM, Enea Data, IntelliCorp, Klasse Objecten, ObjectTime Ltd., Rational Software, Unisys
    • Overview • Tutorial series • UML Quick Tour • Behavioral Modeling „ Part 1: Interactions and Collaborations „ Gunnar Övergaard, Rational Software „ Part 2: Statecharts „ Bran Selic, ObjecTime Limited „ Part 3: Activity Graphs „ Conrad Bock, IntelliCorp Behavioral Modeling with UML 2
    • Tutorial Series • Introduction to UML „ November 1999, Cambridge, US • Behavioral Modeling with UML „ January 2000, Mesa, Arizona, US • Advanced Modeling with UML „ March 2000, Denver, US • Metadata Integration with UML, XMI and MOF „ June 2000, Oslo, Norway 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
    • UML 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 (November 1999) 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 m ajor revision) <<docum ent>> UM L 2.0 << refine>> Other relevant standards TBA Q3 2000 <<docum ent>> (planned m inor revision) << inform alLiaison>> UM L 1.4 ISO Publicly << refine>> Available Specifications (PAS) <<docum ent>> Q3 1999 << form alLiaison> > UM L 1.3 << refine>> E ditorial revision <<docum ent>> with no significant Q2 1998 UM L 1.2 technical changes. << refine>> Q3 1997 U nification of m ajor (OM G Adopted <<docum ent>> m odeling languages, Technology) UM L 1.1 including B ooch, O M T and O bjectory Behavioral Modeling with UML 7
    • OMG UML 1.3 Specification • UML Summary • UML Semantics • UML Notation Guide • UML 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 „ e.g. an object is an instance of a class OR a class is the classifier of an object • specification-realization dichotomy „ 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. run-time „ 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 M eta-M etam odel Lay er <<m e ta m ode l>> (M 3): S pec ifies m eta- MOF Me ta - m etac las s es for the m e ta m ode l UM L m etam odel M etam odel Lay er (M 2): S pec ifies m etac las s es <<m e ta m ode l>> for the UM L UML Me ta m ode l m etam odel, s uc h as Clas s M odel Lay er (M 1): S pec ifies c las s es for the UM L us er Use r Mode l m odels , s uc h as P as s enger, Tic k et, TravelA genc y Us er O bjec ts Lay er (M 0): :Foo :B ar :B az Us er objec ts that are ins tanc es of UM L us er m odel c las s es , s uc h as ins tanc es of P as s enger, Tic k et, TravelA genc y Behavioral Modeling with UML 12
    • Package Structure <<m etam odel>> UM L Behavioral M odel Elem ents M anagem ent dependency Foundation package Behavioral Modeling with UML 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 Gunnar Övergaard, Rational Software gunnaro@it.kth.se • 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 Syntax Instance An entity with a unique identity and (object, to which a set of operations can be name data value, applied (signals be sent) and which attr values component has a state that stores the effects of instance the operations (the signals). etc.) Action A specification of an executable textual statement. A few different kinds of actions are predefined, e.g. CreateAction, CallAction, DestroyAction, and UninterpretedAction. Behavioral Modeling with UML 18
    • Interaction: Core Elements (cont’d) Construct Description Syntax Stimulus A communication between two instances. Operation A declaration of a service that can textual be requested from an instance to effect behavior. Signal A specification of an asynchronous «Signal» Name stimulus communicated between parameters instances. Behavioral Modeling with UML 19
    • Interaction: Core Relationships Construct Description Syntax Link A connection between instances. Attribute Link A named slot in an instance, which textual holds the value of an attribute. Behavioral Modeling with UML 20
    • Example: Instance triangle : Polygon underlined name triangle : Polygon center : Point = (2,2) triangle vertices : Point* = ((0,0), (4, 0), (2,4)) borderColor : Color = black fillColor : Color = white : Polygon attribute links Behavioral Modeling with UML 21
    • Example: Instances and Links : Family husband wife Joe : Person Jill : Person Behavioral Modeling with UML 22
    • Operation and Method Triangle foreach v in vertices do + move (in dist : Point) v.x := v.x + dist.x; + scale (in factor : Real) 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 Collaboration Diagram x y z 1.1: a 1.2: c a x 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 guard-condition sequence-expression return-value := message-name argument-list move (5, 7) 3.7.4: move (5, 7) A3, B4 / [ x < 0 ] C3.1: res := getLocation (fig) 3.7 *[1..5]: move (5, 7) iteration predecessor guard sequence number return value message name argument list 3.7 [ z > 0 ]: move (5, 7) condition Behavioral Modeling with UML 27
    • Different Kinds of Arrows Procedure call or other kind of nested flow of control Flat flow of control Explicit asynchronous flow of control Return Behavioral Modeling with UML 28
    • Example: Different Arrows Nested Flow Flat Flow Asynchronous Flow teller : Order : Article caller exchange callee appl err handl alarm lift receiver getValue dial tone unknown 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 link symbol standard stereotype redisplay () window stimulus : Controller : Window standard standard window «parameter» 1: displayPositions (window) stereotype constraint 1.1.3.1 add (self) wire contents {new} 1.1 *[i := 1..n]: drawSegment (i) «local» line {new} wire :Wire : Line standard 1.1.2: create (r0, r1) «self» stereotype 1.1.3: display (window) standard 1.1.1a: r0 := position () 1.1.1b: r1 := position () constraint left : Bead 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: T Traveler selects ‘change flight itinerary’ option T System retrieves traveler’s account and flight itinerary from client account database T System asks traveler to select itinerary segment she wants to change; traveler selects itinerary segment. T System asks traveler for new departure and destination information; traveler provides information. T If flights are available then … T … T System displays transaction summary. • Alternative course: T 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 2: get customer account 3: get itinerary 7: update information : 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 Description Syntax Collaboration 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 Name roles to be played by instances and links, as well as a set of interactions that define the communication patterns between the instances when they play the roles. Behavioral Modeling with UML 40
    • Collaborations: Core Elements (cont’d) Construct Description Syntax Classifier A classifier role is a specific role Role played by a participant in a / Name collaboration. It specifies a restricted view of a classifier, defined by what is required in the collaboration. Message A message specifies one label communication between instances. It is a part of the communication pattern given by an interaction. Behavioral Modeling with UML 41
    • Collaborations: Core Relationships Construct Description Syntax Association An association role is a specific Role 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 42
    • Classifier-Instance-Role Trichotomy • An Instance is an entity id with behavior and a state, and has a unqiue identity. «originates from» • A Classifier is a description ClassName of an Instance. «conforms to» • A Classifier Role defines a / RoleName «view of» usage (an abstraction) of an Instance. Behavioral Modeling with UML 43
    • Classifier-Instance-Role Trichotomy (cont’d) Classifier ClassifierRole Attribute-1 Attribute-1 Attribute-2 Attribute-2 Attribute-3 «originates from» «conforms to» Operation-1 (…) Operation-1 (…) Operation-3 (…) Operation-2 (…) 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 44
    • Different Ways to Name a Role / ClassifierRoleName : ClassifierName A role name is preceeded by a ‘/’ A classifier name is preceeded by a ‘:’ Example: / Parent : Person / Parent : Person instanceName / ClassifierRoleName : ClassifierName Example: : Person Charlie Charlie : Person Charlie / Parent Charlie / Parent : Person Behavioral Modeling with UML 45
    • Association and Association Role Class Association Class 0..5 Class-1 Class-2 {changeable} «view of» «view of» «view of» {frozen} 3..4 / Role-1 / Role-2 ClassifierRole 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 46
    • Example: A School / Teacher : Person / Student : Person 1 tutor student * position : Text program : Text faculty member * 1 lecturer participant * faculty 1 given course * taken course * : Faculty : Course Behavioral Modeling with UML 47
    • Role Model vs. Class Model The Classes give the complete description while the Roles specify one usage. Role Model Class Model Resulting multiplicity Extra attribute / Teacher : Person 1 * / Student : Person Person 0..1 Resulting multiplicity position : Text program : Text name : Text position : Text * * * program : Text * 1 0..1 1 * 1 * * * * : Faculty : Course Faculty Course Behavioral Modeling with UML 48
    • A Collaboration and Its Roles A Collaboration and how its roles are mapped onto CollaborationName a collection of Classifiers and Associations. roleName-1 roleName-2 roleName-3 Classifier-1 Classifier-2 Behavioral Modeling with UML 49
    • Patterns in UML Constraint that must Handler.reading = length (Subject.queue) be fulfilled in each instance Handler.range = {0..Subject.capacity} of this pattern. Observer Subject Handler CallQueue SlidingBarIcon queue : List of Call reading : Real source : Object color : Color waitAlarm : Alarm range : Interval capacity : Integer Behavioral Modeling with UML 50
    • Generalization Between Collaborations Subject Handler CallQueue Observer SlidingBarIcon Subject Manager ManagedQueue Supervisor 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 51
    • 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 52
    • Collaboration Diagram at Specification Level / Teacher : Person 1 tutor student * / Student : Person position : Text program : Text faculty member * * participant 1 lecturer faculty 1 given course * * taken course : Faculty : Course Behavioral Modeling with UML 53
    • Collaboration Diagram at Instance Level student tutor Alice / Student faculty member John / Teacher participant faculty tutor Bob / Student student : Faculty participant taken course taken course faculty lecturer given course Sara / Teacher English : Course faculty member Behavioral Modeling with UML 54
    • Collaborations including Interactions Sequence Diagram Collaboration Diagram x y z 1.1: a 1.2: c a x y b 1.1.1: b c z Behavioral Modeling with UML 55
    • Collaboration Diagram with Constraining Elements / Generator : Printer Device Constraining Element (A Generalization is not an AssociationRole ) : Laser Printer : Line Printer Behavioral Modeling with UML 56
    • Static Diagram With Collaboration and Classifiers Subject Handler CallQueue Observer SlidingBarIcon Subject Manager ManagedQueue Supervisor Controller Behavioral Modeling with UML 57
    • 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 58
    • 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 59
    • Example: A Booking System Behavioral Modeling with UML 60
    • Use Case Description: Change Flt Itinerary • Actors: traveler, client account db, airline reservation system • Preconditions: Traveler has logged in • Basic course: T Traveler selects ‘change flight itinerary’ option T System retrieves traveler’s account and flight itinerary from client account database T System asks traveler to select itinerary segment she wants to change; traveler selects itinerary segment. T System asks traveler for new departure and destination information; traveler provides information. T If flights are available then … T … T System displays transaction summary. • Alternative course: T If no flights are available then… Behavioral Modeling with UML 61
    • Booking System: Change Flt Itinerary Collaboration 4: get customer account 1: change flight itinerary 7: get itinerary : Traveler / Flight Itenerary Form / DBMS Protocol : Client Account DBMS 10: present 9: display 3: get customer account 2: create modifier 6: get itinerary / Flight Itinerary Modifier 5: create 8: create / Account / Itinerary / ARS Protocol : Airline Reservation System Behavioral Modeling with UML 62
    • 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 63
    • Behavioral Modeling • Part 1: Interactions and Collaborations • Part 2: Statecharts Bran Selic, ObjecTime Limited bran@objectime.com • Part 3: Activity Diagrams Behavioral Modeling with UML 64
    • Overview • Basic State Machine Concepts • Statecharts and Objects • Advanced Modeling Concepts • Case Study • Wrap Up Behavioral Modeling with UML 65
    • 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 66
    • State Machine (Automaton) Diagram • Graphical rendering of automata behavior on Lamp On on off off Lamp Off Behavioral Modeling with UML 67
    • Outputs and Actions • As the automaton changes state it can generate outputs: on on Lamp Lamp On On print(”on”) on/print(”on”) on off off off off Lamp Lamp Off Off Mealy automaton Moore automaton Behavioral Modeling with UML 68
    • Extended State Machines • Addition of variables (“extended state”) on ctr :: Integer ctr Integer Lamp On on/ctr := ctr + 1 off off Lamp Off Behavioral Modeling with UML 69
    • A Bit of Theory • An extended (Mealy) state machine is defined by: „ a set of input signals (input alphabet) „ a set of output signals (output alphabet) „ a set of states „ a set of 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 70
    • Basic UML Statechart Diagram “top” state State Initial Initial pseudostate pseudostate top Trigger Ready Transition stop /ctr := 0 Done Final Action Action state stop Behavioral Modeling with UML 71
    • 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 72
    • Event-Driven Behavior • Event = a type of observable occurrence „ interactions: „ synchronous object operation invocation (call event) „ asynchronous signal reception (signal event) „ occurrence of time instants (time 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 73
    • The Behavior of What? • In principle, anything that manifests event- driven behavior „ NB: there is no support currently in UML for modeling continuous behavior • In practice: „ 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 74
    • • Basic State Machine Concepts • Statecharts and Objects • Advanced Modeling Concepts • Case Study • Wrap Up Behavioral Modeling with UML 75
    • Object Behavior - General Model • Simple server model: Initialize Initialize Handling depends on Handling depends on Object Object specific request type specific request type Wait for Wait for Request Request void:offHook (); Handle Handle {busy = true; obj.reqDialtone(); Request Request … }; Terminate Terminate Object Object Behavioral Modeling with UML 76
    • Object Behavior and State Machines • Direct mapping: on Initialize Object Lamp On Wait for Event on/print(”on”) Handle Event off off Lamp Off Terminate Object stop Behavioral Modeling with UML 77
    • Object and Threads • Passive objects: depend on external power (thread of execution) • Active objects: self-powered (own thread of execution) Initialize Initialize Initialize Initialize Object Object Object Object Wait for Wait for Wait for Wait for Request Request Request Request Handle Handle Handle Handle Request Request Request Request Terminate Terminate Terminate Terminate Object Object Object Object Behavioral Modeling with UML 78
    • Passive Objects: Dynamic Semantics Initialize Initialize Object Object Wait for Wait 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 79
    • Active Objects and State Machines • Objects that encapsulate own thread of execution anActiveObject poll/defer #currentEvent : Event created + start ( ) start start/^master.ready() ready + poll ( ) + stop ( ) ready stop/ poll/^master.ack() Behavioral Modeling with UML 80
    • Active Objects: Dynamic Semantics ActiveObject: • Run-to-completion model: serialized event handling „ eliminates internal concurrency „ minimal context switching overhead Behavioral Modeling with UML 81
    • 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 82
    • • Basic State Machine Concepts • Statecharts and Objects • Advanced Modeling Concepts • Case Study • Wrap Up Behavioral Modeling with UML 83
    • State Entry and Exit Actions • A dynamic assertion mechanism LampOn e2 entry/lamp.on(); exit/lamp.off(); e1 Behavioral Modeling with UML 84
    • Order of Actions: Simple Case • Exit actions prefix transition actions • Entry action postfix transition actions LampOn LampOff off/printf(“to off”); entry/lamp.on(); entry/lamp.off(); exit/printf(“exiting”); exit/printf(“exiting”); Resulting action sequence: off/printf(“needless”); printf(“exiting”); printf(“exiting”); printf(“to off”); printf(“to printf(“exiting”); printf(“exiting”); lamp.off(); printf(“needless”); printf(“needless”); lamp.off(); Behavioral Modeling with UML 85
    • 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 86
    • 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 87
    • 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 88
    • 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 89
    • 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 90
    • Hierarchical State Machines • Graduated attack on complexity „ states decomposed into state machines LampOff LampOff flash/ LampFlashing entry/lamp.off() FlashOn FlashOn off/ entry/lamp.on() 1sec/ 1sec/ on/ on/ FlashOff FlashOff LampOn on/ LampOn entry/lamp.off() entry/lamp.on() Behavioral Modeling with UML 91
    • “Stub” Notation • Notational shortcut: no semantic significance LampOff LampOff flash/ LampFlashing entry/lamp.off() off/ FlashOn on/ on/ LampOn on/ FlashOff LampOn entry/lamp.on() Behavioral Modeling with UML 92
    • Group Transitions • Higher-level transitions Default transition to Default transition to the initial pseudostate the initial pseudostate LampOff LampOff flash/ LampFlashing entry/lamp.off() FlashOn FlashOn off/ entry/lamp.on() 1sec/ 1sec/ on/ FlashOff FlashOff LampOn on/ LampOn entry/lamp.off() entry/lamp.on() Group transition Group transition Behavioral Modeling with UML 93
    • Completion Transitions • Triggered by a completion event „ generated automatically when an immediately nested state machine terminates completion Committing transition (no trigger) Phase1 Phase1 CommitDone Phase2 Phase2 Behavioral Modeling with UML 94
    • Triggering Rules • Two or more transitions may have the same event trigger „ innermost transition takes precedence „ if no transition is triggered, event is discarded LampFlashing FlashOn FlashOn on/ off/ on/ FlashOff FlashOff Behavioral Modeling with UML 95
    • Order of Actions: Complex Case • Same approach as for the simple case S1 S2 exit/exS1 entry/enS2 initS2 S11 E/actE S21 exit/exS11 entry/enS21 Actions execution sequence: exS11 Ö exS1 Ö actE ÖenS2 Ö initS2 Ö enS21 Behavioral Modeling with UML 96
    • History • Return to a previously visited hierarchical state „ deep and shallow history options Diagnosing suspend/ Diagnostic1 Diagnostic1 Diagnostic2 Diagnostic2 Step11 Step11 Step21 Step21 resume/ Step12 Step12 Step22 Step22 H* H* Behavioral Modeling with UML 97
    • Orthogonality • Multiple simultaneous perspectives on the same entity age financialStatus Child Poor Adult Rich Retiree Behavioral Modeling with UML 98
    • Orthogonal Regions • Combine multiple simultaneous descriptions age financialStatus Child Poor Adult age financialStatus Child Rich Retiree Poor Adult Retiree Rich Behavioral Modeling with UML 99
    • Orthogonal Regions - Semantics • All mutually orthogonal regions detect the same events and respond to them “simultaneously” „ usually reduces to interleaving of some kind legalStatus financialStatus LawAbiding LawAbiding Poor Poor robBank/ robBank/ Outlaw Outlaw Rich Rich Behavioral Modeling with UML 100
    • Interactions Between Regions • Typically through shared variables or awareness of other regions’ state changes sane : Boolean sane : Boolean flying : Boolean flying : Boolean Catch22 Catch22 sanityStatus flightStatus Crazy Crazy Flying Flying entry/sane := false; entry/sane := false; entry/flying := true; entry/flying := true; (flying)/ (sane)/ request Grounding/ (~sane)/ Sane Sane Grounded Grounded entry/sane := true; entry/sane := true; entry/flying := false; entry/flying := false; Behavioral Modeling with UML 101
    • Transition Forks and Joins • For transitions into/out of orthogonal regions: age Child Child Adult Adult Retiree Retiree Staff Staff Manager Manager Member Member employee Behavioral Modeling with UML 102
    • Common Misuse of Orthogonality • Using regions to model independent objects Person1 Person2 Person1 Person2 Child Child Adult Adult Retiree Retiree Behavioral Modeling with UML 103
    • • Basic State Machine Concepts • Statecharts and Objects • Advanced Modeling Concepts • Case Study • Wrap Up Behavioral Modeling with UML 104
    • Case Study: Protocol Handler • A multi-line packet switch that uses the alternating-bit protocol as its link protocol AB protocol AB protocol AB End user sender line card 1 . unreliable AB End user receiver . telecom lines . AB sender AB SWITCH receiver End user line card N Behavioral Modeling with UML 105
    • Alternating Bit Protocol (1) • A simple one-way point-to-point packet protocol AB protocol AB 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 106
    • Alternating Bit Protocol (2) • State machine specification Sender SM Receiver SM AcceptPktA RcvdPktA ackB/^ack pktA/^data data/^pktA ack/^ackA timeout/^pktB timeout/^ackB WaitAckA WaitAckB WaitPktB WaitPktA timeout/^pktA timeout/^ackA ackA/^ack data/^pktB pktB/^data ack/^ackB AcceptPktB RcvdPktB Behavioral Modeling with UML 107
    • Additional Considerations • Support (control) infrastructure operator System AB interface operator receiver AB lines manager AB sender DB interface SWITCH DBase Behavioral Modeling with UML 108
    • 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 109
    • Retrofitting Control Behavior Hardware JustCreated Audit Analysing Failure ReadyToGo GettingData AcceptPktA Failed WaitAckA WaitAckB AcceptPktB Behavioral Modeling with UML 110
    • The Control Automaton • In isolation, the same control behavior appears much simpler JustCreated GettingData Analysing Failure Hardware Audit ReadyToGo Failed Operational Behavioral Modeling with UML 111
    • Exploiting Inheritance • Abstract control classes can capture the common control behavior AbstractController Sender Receiver . . . Behavioral Modeling with UML 112
    • Exploiting Hierarchical States Analysing AbstractController JustCreated Failure GettingData Failed Hardware Audit Sender ReadyToGo Operational Behavioral Modeling with UML 113
    • • Basic State Machine Concepts • Statecharts and Objects • Advanced Modeling Concepts • Case Study • Wrap Up Behavioral Modeling with UML 114
    • Wrap Up: Statecharts • UML uses an object-oriented variant of Harel’s statecharts „ adjusted to software modeling needs • Used to model event-driven (reactive) behavior „ 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 115
    • 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 116
    • Behavioral Modeling • Part 1: Interactions and Collaborations • Part 2: Statecharts • Part 3: Activity Diagrams Conrad Bock, Intellicorp bock@intellicorp.com Behavioral Modeling with UML 117
    • 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 118
    • 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. Start Weather Info Analyze Weather Info Analyze Weather Info Not UML Chart Course Chart Course Cancel Trip Notation! Cancel Trip Behavioral Modeling with UML 119
    • 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 Product Design Product Acquire Capital Acquire Capital Procure Procure Materials Materials Build Build Build Build Subassembly 11 Subassembly 22 Subassembly Subassembly Not UML Final Final Assembly Assembly Notation Behavioral Modeling with UML 120
    • 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 To Start Ready To Start Coin Deposited Ready For Order Ready For Order Selection Cancel Button Made Pressed Dispense Return Return Dispense Change Product Product Change Not UML Notation Behavioral Modeling with UML 121
    • 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 quot;statequot; is used in the element names. • Activity graphs will become independent of state machines in UML 2.0. Behavioral Modeling with UML 122
    • Kinds of Steps in Activity Diagrams • Action (State) Action • Subactivity (State) 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 123
    • 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 124
    • Subactivity (State) Subactivity • A subactivity (state) starts another activity graph without using an operation. • Used for functional decomposition, non- polymorphic applications, like many workflow systems. • The invoked activity graph can be used by many subactivity states. Behavioral Modeling with UML 125
    • Example POEmployee.sortMail Deliver Mail Deliver Mail POEmployee sortMail() Check Out Put Mail Truck In Boxes Behavioral Modeling with UML 126
    • Activity Graph as Method POEmployee.sortMail POEmployee.deliverMail POEmployee PO Employee Deliver Mail Method sortMail() «realize» deliverMail() Check Out Put Mail Truck In Boxes • Application is completely OO when all action states invoke operations, and all activity graphs are methods for operations. Behavioral Modeling with UML 127
    • 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 1.4. Behavioral Modeling with UML 128
    • 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 129
    • Object Flow (State) Order Take Order Fill Order [Taken] • 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 130
    • Coordinating Steps • Inherited from state machines • Initial state • Final state • Fork and join Behavioral Modeling with UML 131
    • Coordinating Steps • Decision point and merge ( ) are inherited from state machines. • For modeling conventional flow chart decisions. Calculate [cost < $50] Charge Cost Account [cost >= $50] Get Authorization Behavioral Modeling with UML 132
    • Coordinating Steps • Synch state ( ) is inherited from state machines but used mostly in activity graphs. • Provides communication capability between parallel processes. State machine notation Put Build Install Frame On Walls Roof Install Inspect Foundation * * Install Install Install Electricity Electricity Electricity in Foundation In Frame Outside Behavioral Modeling with UML 133
    • Convenience Features (Synch State) • 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). Activity diagram notation Put Build Install Frame On Walls Roof Install Inspect Foundation Install Install Install Electricity Electricity Electricity in Foundation In Frame Outside Behavioral Modeling with UML 134
    • Convenience Features (Synch State) • Object flow states can be synch states A 11 A 12 A 13 O bj [S 2] A 21 A 22 A 23 Behavioral Modeling with UML 135
    • Convenience Features • Fork transitions can have guards. Evaluate Revise [ priority = 1] Impact Plan Register Release Bug Fix Fix Test Bug Fix • Instead of doing this: [ priority = 1] Evaluate Revise Impact Plan Register Release [else] Bug Fix Fix Test Bug Fix Behavioral Modeling with UML 136
    • 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 Revise Impact Plan [ priority = 1] Support Register Release Bug Fix Engineering Fix Test Bug Fix Behavioral Modeling with UML 137
    • Convenience Features • Signal send icon Wake Up Signal • … translates to a transition Turn on Coffee Pot with a send action. Get Cups Coffee Pot • Signal receipt icon Signal Coffee Done • … translates to a wait state (an state with no action and a signal trigger event). Drink Coffee Behavioral Modeling with UML 138
    • partition Submission Team Task Force Revision Task Force initial state action state control flow Begin fork of control Case Study Develop technology Issue RFP specification RFP [issued] conditional fork join of control Submit specification draft object flow Specification [optional] input value [initial proposal] Collaborate with competitive Communications of the ACM submitters Evaluate initial submissions Kobryn, “UML 2001” Finalize October 1999 Adapted from specification Specification [final proposal] Behavioral Modeling with UML 139
    • Collaborate with competitive submitters Evaluate initial submissions Finalize specification Specification [final proposal] Case Study Evaluate final submissions Vote to recommend guard Specification [YES] [NO] [adopted] decision Revise specification Implement specification Communications of the ACM Specification [revised] Enhance Recommend specification revision Kobryn, “UML 2001” October 1999 Adapted from [else] [Enhanced] final state Behavioral Modeling with UML 140
    • 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 141
    • 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 142
    • Activity Diagram Modeling Tips From UML Customer Telesales Accounting Warehouse User Guide: Request Return Get Return Number Ship Item Receive Item Item [returned] Restock Item Credit Item Account [available] Behavioral Modeling with UML 143
    • Customer Telesales Accounting Warehouse Request Return Get Return Number Ship Item Activity Modeling Tips Receive Item Item [returned] Restock Item Credit Account Item [available] Behavioral Modeling with UML 144
    • 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 145
    • Activity Diagram Modeling Tips Well-nested: Behavioral Modeling with UML 146
    • Activity Diagram Modeling Tips Not well-nested: Apply structured coding principles. (Be careful with goto’s!) Behavioral Modeling with UML 147
    • Activity Diagram Modeling Tips Can be translated to well-nested diagram on earlier slide: Behavioral Modeling with UML 148
    • 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 149
    • Preview - Next Tutorial • Advanced Modeling with UML „ Model management „ Standard elements and profiles „ Object Constraint Language (OCL) Behavioral Modeling with UML 150
    • Further Info • Web: „ OMG UML Resource Page „ www.omg.org/uml/ „ UML Tutorial 1 (OMG Document omg/99-11-04) „ www.omg.org/cgi-bin/doc?omg/99-11-04 „ UML Tutorial 2 (OMG Document number TBA) • Email „ Gunnar Övergaard: gunnaro@it.kth.se „ Bran Selic: bran@objectime.com „ Conrad Bock: bock@intellicorp.com • Conferences & workshops „ UML World 2000, NYC, March ‘00 „ UML ’00, York, England, Oct. ‘00 Behavioral Modeling with UML 151