2 Introduction UML stands for Unified Modeling Language. It is a standard language for specifying, visualizing, constructing, and documenting the artifacts of software systems.SpecifyingVisualizingConstructingDocumentingBusiness ModelingCommunications
3 UML Building Blocks Class: Class represents set of objects having similar responsibilities.Use case:Use case represents a set of actions performed by a system for a specific goal.Interaction:Interaction is defined as a behavior that consists of a group of messages exchanged among elements to accomplish a specific task.
4 Cont . . .State machine:State machine is useful when the state of an object in its life cycle is important.It defines the sequence of states an object goes through in response to events. Events are external factors responsible for state change.Note:A note is used to render comments, constraints etc of an UML element.
5 Cont . . . Generalization: Aggregation: Composition: Generalization can be defined as a relationship which connects a specialized element with a generalized element. It basically describes inheritance relationship in the world of objects.Aggregation:Whole part relationship i.e. large part “whole” contains one or more parts. E.g. building “whole” contains rooms ”parts”Composition:Is a relationship in which if the “whole” part dies, the child has to die as well. E.g. if building collapse , rooms no more exist
6 UML Models, Views, Diagrams UML is a multi-diagrammatic languageEach diagram is a view into a modelDiagram presented from the aspect of a particular stakeholderProvides a partial representation of the systemIs semantically consistent with other viewsExample views
8 UML DiagramsUML diagrams are the ultimate output of the entire discussion.All the elements, relationships are used to make a complete UML diagram and the diagram represents a system.UML includes the following nine diagramsClass diagramObject diagramUse case diagramSequence diagramCollaboration diagramActivity diagramState chart diagramDeployment diagramComponent diagram
9 UML Modeling TypesDifferent diagrams are used for different type of UML modeling.There are three important type of UML modeling :Structural modeling:Structural modeling captures the static features of a system.They consist of the followings: Class diagrams , Objects diagrams , Deployment diagrams , Component diagram etcStructural model represents the framework for the system and this framework is the place where all other components exist.They all represent the elements and the mechanism to assemble them.E.g. class written once remain same through out the execution.
10 Cont . . . Behavioral Modeling: Behavioral model describes the interaction in the system.It represents the interaction among the structural diagrams.Behavioral modeling shows the dynamic nature of the systemActivity diagrams , Interaction diagrams, Use case diagramsDepends upon the behavior of an object/entity object can have more then one state, and depending upon its state its behavior would be different.E.g. bank account may be working(deposit/ withdraw)Not working(closed/ dead)
11 Cont . . . Dynamic Modeling: The dynamic model is used to express and model the behavior of the system over time.It includes support for activity diagrams, state diagrams, sequence diagramse.g. user login(id, password), valid tries to login , its set of sequences will be different as compared to an invalid user.
12 Use-Case DiagramUse Case Diagram is used to describe the functionalities provided by a system and the users associated with that system.The Use case diagram is used to identify the primary elements and processes that form the system.The primary elements are termed as "actors" and the processes are called "use cases."The Use case diagram shows which actors interact with each use case.
13 Use-Case Diagram The main purpose of the use-case diagram is: to help development teams visualize the functional requirements of a systemTo help identify relationship of "actors" (human beings who will interact with the system) with essential processesand understand the relationships among different use cases
14 Elements of a use-case diagram Use-case diagrams contain the following elements:Actors, which represent users of a system, including human users and other systems.Use Cases, which represent functionality or services provided by a system to users.
15 UML notation used to represent an actor Definition:The outside entity which communicates with the system:A Person (user)An external systemPhysical EnvironmentAn Actor has a unique name and an optional descriptionSymbol:UML notation used to represent an actor
16 Actor (Example)Consider the following scenario related to a “University Management System” :In a university management system, a Student can submit the assignments, the instructor marks those assignments and then uploads the result. The Student is allowed to view the Results.Now, by recalling the definition of actor, can you identify the actors in this System?StudentInstructor
17 Actor (Example/2) Student Instructor Student is an external entity which interacts with the system. Student is a user of this system, as some services are used by it.Instructor is another external entity which interacts with the university management system.StudentInstructor
18 Use-caseRepresent functionality or services provided by a system to users.It is a description of set of sequence of actions that a system perform that produces an observable result.A use case represents a class of functionality provided by the system as an event flow.Use cases describe the interaction between a primary actor and the system itself
19 UML notation used to represent a use-case The use case technique is used in software and systems engineering to capture the functional requirements of a system.Each use case describes how the actor will interact with the system to achieve a specific goal.One or more scenarios may be generated from each use case, corresponding to the detail of each possible way of achieving that goal.Symbol :UML notation used to represent a use-case
20 Use-case (Example) Consider the same example again: In a university management system, a Student can submit the assignments, the instructor marks those assignments and then uploads the result. The Student is allowed to view the Results.Now, by recalling the definition of use-case, can you identify the use-cases in this System?Submit AssignmentsMark AssignmentsUpload ResultsView Results
21 Use-case (Example/2)The use-cases are linked with the functional requirements of this system. In this example :Student submit the assignments.Instructor marks the assignments.Instructor upload the marks.Student can view the marks.It is now clear that how actors are interacting with different use-cases of this system.Now, lets combine actors and use-cases in one diagram?
22 Symbols in Use-Case Diagrams ACTORUSE-CASEINTERACTION:denotes set of messages exchanged among objectsNOTES/COMMENTS
23 Use-Case Diagram (University Management System) SYSTEM BOUNDARYSubmit AssignmentsMark AssignmentsStudentUpload ResultsView ResultsInstructorPackage: University Management System
24 Cont . . . Other types of associations and relationships; Generalization between use casesGeneralization between actorsInclude relationship between use casesExtend relationship between use cases
25 Generalization between Use cases Represented by a line and a hollow arrowFrom child to parentA use case generalization shows that one use case is simply a special kind of another.A child can be substituted for its parent whenever necessary.Generalization appears as a line with a triangular arrow head toward the parent use caseChild use caseParent use case
26 Example Example : ATM Register car sharer CarMatch AdministratorWeb ServerRegister car sharerTransfer car sharer from web serverManually add car sharerExample : ATM
27 Generalization between Actors (examples) studentForeign studentLocal student
28 Include relationship between use cases Some times one use case includes the functionality of another use case.Include relationship is drawn as an open arrow with dashed lines that points towards the use case that is being includedThe word include is written in << >>OrIf x is a task and y is a sub task but acting as a part of it then use <<include >> stereotypeArrowhead towards the subtask
30 Extend relationship between use cases There are occasions where one use case may optionally be extended by the functionality in another use case.The relationship is drawn as an open arrow with dashed line the points towards the use case that is being extended.The word extend is written in <<……..>>OrIf x is a task and y is a sub task of x but little bit differentArrow head towards the main task
32 Practice Read the following case : Identify the actors Identify (extract ) the use casesConstruct a proper use-case diagram (with proper symbols & notations)
33 Case-StudyConsider the Library Management System of UOW. A Student is allowed to issue books for a period of two weeks. Student can read newspapers/magazines in the library and can even access the databases for e-books. The Library Staff is responsible for maintaining the records of students and along with the issued books. The Staff marks an entry in the register whenever a student issue or return a book. A fine is charged on a student if he/she fail to return the book on time. The Librarian is there to manage the staff, check the records and prepare reports for DG/DEAN.
34 Class diagrams Gives a graphical representation of domain model. It represents relationship of classes objects with object specification in detail.It gives static view of the systemEach class is represented by a rectangle subdivided into three compartmentsNameAttributesOperations
35 Class Diagram: Visibilities Modifiers are used to indicate visibility of attributes and operations.‘+’ is used to denote Public visibility (everyone)‘#’ is used to denote Protected visibility (derived)‘-’ is used to denote Private visibility (no one)By default, attributes are hidden and operations are visible.The last two compartments may be omitted to simplify the class diagrams
36 An example of Class Account_Name - Custom_Name - Balance Name +AddFunds( )+WithDraw( )+Transfer( )NameAttributesOperations
37 Other representations of class Boeing 737Boeing 737length: meterfuelCapacity: Galdoors: intlift ( )roll ( )thrust ( )Boeing 737length: meterfuelCapacity: Galdoors: intBoeing 737lift()roll()
38 Class Attributes (Cont’d) PersonAttributes are usually listed in the form:attributeName : TypeA derived attribute is one that can becomputed from other attributes, butdoesn’t actually exist. For example,a Person’s age can be computed fromhis birth date. A derived attribute isdesignated by a preceding ‘/’ as in:/ age : Datename : Stringaddress : Addressbirthdate : Date/ age : Datessn : Id
39 Class Attributes (Cont’d) Person+ name : String# address : Address# birthdate : Date/ age : Date- ssn : IdAttributes can be:+ public# protected- private/ derived
40 Class Diagram: Association Associations represent relationships between instancesof classes .An association is a link connecting two classes.Bi-directional association Associations are assumed to be bi-directionalUni-directional association e.g. Bank Account and personBankAccountPersonBankAccountPerson
41 Association: Multiplicity and Roles InstructorStudent1..*learns fromteachesMultiplicitySymbol Meaning1 One and only one0..1 Zero or oneM..N From M to N (natural language)* From zero to any positive integer0..* From zero to any positive integer1..* From one to any positive integerNote: if no multiplicity is given it is assumed to be 1Association name: represents natureof participants classes in a relationship.Association Role: role played by theparticipant class
42 Notation of Class Diagram: Generalization StudentTeachingAssistantEmployeeSubtype2SupertypeSubtype1PersonStudentGeneralization expresses a relationship among related classes. It is a class that includes its subclasses.
44 Notation of Class Diagram: Composition Class WClass P1Class P2COMPOSITIONWhole ClassPart ClassesAutomobileEnginewindowsExampleComposition: expresses a relationship among instances of related classes.It is a specific kind of Whole-Part relationship.It expresses a relationship where an instance of the Whole-class has the responsibility to create and initialize instances of each Part-class. Composition should also be used to express relationship where instances of the Whole-class have exclusive access to and control of instances of the Part-classes.
46 Notation of Class Diagram: Aggregation Aggregation: expresses a relationship among instances of related classes. It is a specific kind of Container-Containee relationship.It expresses a relationship where an instance of the Container-class has the responsibility to hold and maintain instances of each Containee-classAggregation is appropriate when Container and Containees have no special access privileges to each other.Class CClass E1Class E2AGGREGATIONContainer ClassContainee ClassesBagApplesMilkExample
48 Aggregation vs. Composition Composition is really a strong form of aggregationcomponents have only one ownercomponents cannot exist independent of their owner;both have coincident lifetimescomponents live or die with their ownere.g. (1)Each car has an engine that can not be share with other car(2) If the polygon is destroyed, so are the points.Aggregations may form "part of" the aggregate, but may not be essential to it.They may also exist independent of the aggregate. Less rigorous than a compositione.g. (1)Apples may exist independent of the bag.(2)An order is made up of several products, but the products are still there even if an order is cancelled.
49 Class Diagram example class * Multiplicity: mandatory Association Order-dateReceived-isPrepaid-number :String-price : Money+dispatch()+close()Customer-name-address+creditRating() : String()Corporate Customer-contactName-creditRating-creditLimit+remind()+billForMonth(Integer)Personal Customer-creditCard#OrderLine-quantity: Integer-price: Money-isSatisfied: BooleanProduct*1Employee0..1OperationsAttributesNameAssociationMultiplicity: mandatoryMultiplicity:Many valueMultiplicity: optionalGeneralizationclass
50 Interaction DiagramsIn object oriented systems, tasks are performed by objects interacting with other by passing messages.In UML this interaction is provided by sequence diagrams.Class diagrams model static nature of systemInteractions diagrams model the dynamic nature of system and emphasis the order of the message over time
51 Cont . . .squares with object type, optionally preceded by object name and colon
52 Purpose of interaction diagrams These are used to model :high level interaction between active objects in systemInteraction between objects involved in a use caseInteraction between objects involved in an operationGeneric interactions (showing all possible paths through interaction)
53 Sequence DiagramShows how objects communicate with each other over time.That is, sequence diagrams are used to model object interactions arranged in time sequence and to distribute use case behavior to classes.They can also be used to illustrate all the paths a particular use case can ultimately produce.The sequence diagram consists of Active Objects, Messages represented as solid-line arrows, and Time represented as a vertical progression.
54 Sequence Diagram - Objects A life line illustrates what is happening to an object in a chronological fashion.:NameLife lineActivation(focus of control)Object
55 Sequence Diagram – Time & Messages Messages are used to illustrate communication between different active objects of a sequence diagram.:Name1:Name2Message TwoActorMessage One
56 Types of MessagesSynchronous (flow interrupt until the message has completed.1st object waits until the 2nd object completes its operationsAsynchronous (don’t wait for response)1st object does not wait for the 2nd object tocompletes its operationsFlat – no distinction between sysn/asyncReturn – control flow has returned to the caller.
57 Steps in drawing a sequence diagram 1.Decide the context of the interactionSystem, subsystem, use case or operation2. Identify the structural elements(objects) necessary to carry our functionality of use case3. Consider alternative scenario that may be required4. Draw the sequence diagramLayout the objects from left to rightStarting with the message that starts the interactionAdd focus of controlAdd timing constructs
59 Example :making phone call CallerPhoneRecipientPicks upDial toneDialRing notificationRingHello
60 Task 1 Draw a sequence diagram for: In Beauty and the Beast kitchen items came to life. Draw a sequence diagram for making a peanut butter and jelly sandwich if the following objects are alive: knife, peanut butter jar (and peanut butter), jelly jar (and jelly), bread, plate. I may or may not want the crusts cut off. Don’t forget to open and close things like the jars, and put yourself away, cleanup, etc…
61 Task 2Draw a sequence diagram showing a customer’s interaction to withdraw money from ATM .Show all sequence of steps involved e.g. insert card, enter pin number , amount etc.
62 Activity diagrams Purpose of Activity diagrams is listed as under : Are a means of describing workflowsCan be used as an analysis tool to describe business flows in different level of detailDescribe complex flows within or between use caseAt design level, it can be use to describe flow within an operation.
64 Notations An activity is a unit of work that needs to be carried out symbol used to represent an activityEach activity can be followed by another activity (sequencing).Activity name
65 Triggering an activity There are four ways in which an activity can be triggeredOn Entry: these actions are triggered as soon as the activity startsDo: these actions take place during the life time of the activityOn Event: these actions take place in response to an eventOn Exit: these actions takes place just before the activity completes
66 Cont . . . Actions -> is triggering of an event Activity name Entry/ actionDo/actionEvent name/actionExit/action
67 States & ActivitiesA state in an activity diagram is a point where some event needs to take place before activity continuesActivities & states are roughly equivalent and states can carry out actions just as an activity can.However activities need to complete all their actions before exiting normally.States are used to imply waiting, not doingWait forpayment
68 Cont . . . There are two special states: Start State: is the entry point to a flowOnly one start state is allowed in an diagramShows as a block dot and is labeledEnd State: are drawn as black dots with a surrounding circle
69 Transition Transition : Is the movement from one activity to another The change from one state to anotherThe movement between states and an activity in either direction.A transition normally occurs when all the actions of an activity have been completed.Or when an event triggers the exit from a particular state or activity.Are shown as arrowed lined between two activityWait forpaymentRequest payment
70 Cont . . . There are two types of transitions: Trigger-less transitions: are permissible when exiting activities, and meaning is that the activity has completed all its actions and next phase of workflow can beginTriggered Transitions: when exiting a state, some event needs to trigger it.E.g. when waiting for payment, exit from the state could be triggered by a PaymentArrives eventWait forpaymentRequest paymentPaymentArrives
71 Cont . . .There can be more than one transition out of a single activity or a state.This is used when different events results in a state or activity terminationWait forpaymentChase paymentProcess paymentPaymentPeriodExpiresPaymentArrives (amount)
72 Decision PointsA decision points in a workflow where the exit transition from a state or an activity may branch in alternative directionDepending on a conditionRepresented by a diamond.
73 Synchronisation bar Synchronisation bar. All triggers from this attach to activities that can occur in parallel, with no specific sequence, or concurrently.Symbolor
74 Example Process payment Update cash balance Process Cheque Clear Debt Cheque paymentCash paymentClear Debt
75 Activity Diagrams - Notation Start at the top black circleIf condition 1 is TRUE, go right; if condition 2 is TRUE, go downAt first bar (a synchronization bar), break apart to follow 2 parallel pathsAt second bar, come together to proceed only when both parallel activities are done
78 Creating an activity diagram Modelling a workflow in an activity diagramIdentify a workflow objective.Decide the pre and post-conditions of the workflow.Define all activities and states.Define any objects that are created or modified.Decide on responsibility for performing the activities.Connect all elements on the diagram with transitions.Place decisions on the diagram.Evaluate your diagram for concurrent workflows.Set all actions, triggers and guard conditions in the specifications of each model element.
79 TaskDraw an activity diagram to issue book from library