UML Behavioral Models

Transcription

1 UML Behavioral Models Dept. of Computer Science Baylor University Some slides adapted from materials in the following sources: UMLTutorial by Dr. R. France, Lecture slides by Dr. C. Constantinides Specifying behavior using the UML Class models describe objects and their relationships Behavior can be specified in terms of operation pre and postconditions, but behavior is not the primary focus of a class model Behavioral models in the UML Interaction models: describe interactions among objects State models: describe control aspects of a system provides descriptions sequences of operations without regard for what the operation do. Activity models: description of a behavioral feature expressed in terms of sequences of steps. Behavioral Models-1 Behavioral Models-2 Introduction to UML interaction diagrams: 1) Communication diagrams 2) Sequence diagrams message1( ) :ClassAInstance 1: message2() 2: message3() :ClassBInstance :ClassAInstance :ClassBInstance message2() message3() Interaction diagrams illustrate how objects interact via messages. Communication diagrams illustrate object interactions in a graph or network format. Behavioral Models-3 Sequence diagrams illustrate interactions in a kind of fence format. Set of all operation contracts defines system behaviour. We will create an interaction diagram for each operation contract. Behavioral Models-4 Comm. diagram vs. Seq. diagram Communication diagram message1( ) :ClassAInstance Sequence diagram 1: message2() 2: message3() :ClassBInstance Example communication diagram: makepayment direction of message first internal message makepayment(cashtendered) 1: makepayment(cashtendered) :ClassAInstance :ClassBInstance parameter link line 1.1: create(cashtendered) message2() first message instance object creation message3() Behavioral Models-5 Behavioral Models-6 1

2 How to read the makepayment communication diagram Example sequence diagram: makepayment makepayment(cashtendered) 1: makepayment(cashtendered) 1.1: create(cashtendered) makepayment (cashtendered) makepayment (cashtendered) 1. The message makepayment is sent to an instance of Register. The sender is not identified. 2. The Register instance sends a makepayment message to a Sale instance. 3. The Sale instance creates an instance of Payment. create (cashtendered) Behavioral Models-7 Behavioral Models-8 Illustrating classes and instances Messages to self or this Sale Class Instance msg1() s1 Named instance 1: clear() To show an instance of a class, the regular class box graphic symbol is used, but the name is underlined. Additionally a class name should be preceded by a colon. An instance name can be used to uniquely identify the instance. A message can be sent from an object to itself. This is illustrated by a link to itself, with messages flowing along the link. Behavioral Models-9 Behavioral Models-10 Creation of instances makenewsale( ) 1: create () makepayment() makepayment( ) newly created instance create( ) The language independent creation message is create, being sent to the instance being created. The create message may include parameters, indicating passing of initial values. An object lifeline shows the extend of the life of an object in the diagram. Note that newly created objects are placed at their creation height. Behavioral Models-11 Behavioral Models-12 2

3 Conditional messages: 1) communication diagrams msg1 ( ) 1: [new sale] create () 2) Sequence diagrams :A :B [color=red] calculate() A conditional message is shown by following a sequence number with a conditional clause in square brackets, similar to the iteration clause. The message is sent only if the clause evaluates to true. Guard condition in UML 1.x. Interaction Fragments (e.g., alt, opt) are introduced in UML 2.x. Behavioral Models-13 Behavioral Models-14 Mutually exclusive conditional paths: Example 1 Mutually exclusive conditional paths: Example 2 unconditional after either msg2() or msg4() 2: msg6() :ClassE 1a and 1b are mutually exclusive conditional paths. Both are sequence number 1 since either could be the first internal message. :A :B :C [x<10] calculate() msg1 ( ) :ClassA 1a: [test1] msg2() :ClassB [x>15] calculate() :ClassD 1b: [not test1] msg4() 1b.1: msg5() :ClassC 1a.1: msg3() In UML 2.x., alt Interaction Fragment. Behavioral Models-15 Behavioral Models-16 Iteration or looping Examples with different kinds of arrows msg1( ) 1*: li := nextlineitem(): SalesLineItem or 1*: [i :=1..10] li := nextlineitem(): SalesLineItem Iteration is indicated by following the sequence number with a star * This expresses that the message is being sent repeatedly, in a loop, to the receiver. It is also possible to include an iteration clause indicating the recurrence values. Nested Flow teller : Order : Article getvalue price getname Flat Flow caller exchange callee lift receiver dial tone dial digit dial digit ringing tone ringing signal lift receiver Behavioral Models-17 Behavioral Models-18 3

4 Interaction modeling tips Set the context for the interaction. Include only those attributes of the objects that are relevant. Express the flow from left to right and from top to bottom. Put active objects 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 Advanced concepts in UML interaction models Object interactions are described in terms of Collaborations: descriptions of object structures that support required behaviors Interactions: descriptions of communication structures that support required behaviors Interaction diagrams allow one to view only the parts of a system involved in accomplishing use case goals Behavioral Models-19 Behavioral Models-20 Key definitions Collaboration: a collaboration defines the roles a set of objects play when performing a particular task, e.g. a task specified by a use case. Interaction: an interaction specifies a communication pattern to be performed by instances playing the roles of a collaboration. Interaction context Class or Collaboration Behaviors (Interactions) Internal Structure Part A collaboration identifies the objects that will interact to perform some service An interaction context identifies the collaboration and interactions sd GoHome GoHomeServiceContext sd Authorization :ServiceTerminal ServiceUser ServiceBase ServiceTerminal Other concepts which may themselves have an internal structure Behavioral Models-21 Behavioral Models-22 A more complex Sequence Diagram (UML 2.0) Frame and Name Lifeline is an object Interaction Occurrence Combined Fragment Plain asynchronous message sd GoHomeSetup opt SetHome SetInvocationTime SB_GoHomeSetup Authorization SetTransportPerences :ServiceTerminal sd Authorization Code OK SB_Authorization OK OnWeb :ServiceTerminal Combined fragment types Alternatives (alt) choice of behaviors at most one will execute depends on the value of the guard ( else guard supported) Option (opt) Special case of alternative Break (break) Represents an alternative that is executed instead of the remainder of the fragment (like a break in a loop) Parallel (par) Concurrent (interleaved) sub-scenarios Negative (neg) Identifies sequences that must not occur Behavioral Models-23 Behavioral Models-24 4

5 r Combined fragment types Combined fragments and data Critical Region (region) Traces cannot be interleaved with events on any of the participating lifelines Assertion (assert) Only valid continuation Loop (loop) Optional guard: [<min>, <max>, <Boolean-expression>] No guard means no specified limit loop Choice Operand Separator Guarding InteractionOperand with an InteractionConstraint sd GoHomeInvocation(Time invoc) :Clock :ServiceTerminal [Now>invoc] InvocationTime TransportSchedule loop alt [Now>interv+last] ScheduleIntervalElapsed TransportSchedule [pos-lastpos>dist] GetTransportSchedule TransportSchedule FetchSchedule Behavioral Models-25 Behavioral Models-26 Referencing interaction diagrams Interaction Frame sd ATM-transaction Lifeline is one object or a part Interaction Occurrence Interaction Overview Diagram Interaction with the syntax of Activity Diagram sd GoHomeSetup Authorization client: atm: dbase: insertcard CheckPin sd CheckPin client: atm: dbase: Interaction Occurrence sd askforpin SetHome alt DoTransaction error(badpin) [chk= OK] [else] data(pin) result(chk) check(pin) result(chk) Expanded sequence diagram sd SetInvocationTime SetTransportPerences Combined (in-line) Fragment Behavioral Models-27 Behavioral Models-28 Timing Diagram Duration constraint StateInvariant sd UserAcc_User {d..3*d} Lifeline WaitAccess :User WaitCard CardOut Time constraint Idle Code OK {t..t+3} t Time values Message event Timing ruler Behavioral Models-29 Behavioral Models-30 5

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