Www.ddss.arch.tue.nl 7M822 UML Use Case Diagram / Use Case Text / Activity Diagram 23 September...

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7M822

UML Use Case Diagram /Use Case Text / Activity Diagram

UML Use Case Diagram /Use Case Text / Activity Diagram

23 September 2010


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Requirements analysisRequirements analysis

Figure out what the users and customers of a software effort want the system to do.– A class diagram drawn from the conceptual perspective (, which

can be a good way of building up a rigorous vocabulary of the domain)

– Use cases, which describe how people interact with the system


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Needs

Features

Software requirements

problemdomain

solutiondomain


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Use Case approachUse Case approach

Lending services

User administration

Books database

Library user

Library staff

library system

Lending services


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Use Case modellingUse Case modelling

• Use Case model – A model that describes the functional requirements of a system in terms of use cases.

• A use case model partitions system functionality into– requirements / goals / transactions (‘use cases’) that are– meaningful to users (‘actors’);

and is shown on a use case diagram

• System developers and customers/end-users discuss a use case model. {In an iterative process, this lead to a requirement specification on which all agree.}


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UML ViewsUML Views

Design view

Interaction view

Implementa-tion view

Deployment view

Use Case view

vocabularyfunctionality

behaviour

performancescalabilitythroughput

system assemblyconfiguration management

system topologydistributiondeliveryinstallation

physicallogical


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Use Case definitionUse Case definition

• Fowler:– A use case is a typical interaction that a user has with a system in

order to achieve some goals.– A use case is a description of a set of sequence of actions,

including variants, that a system performs to yield an observable result of value to an actor.

• Cockburn:– A use case describes a system’s behavior.


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ActorActor

• An actor is someone or something that interacts with the system. It is who or what uses the system.

• An actor communicates with the system by sending and receiving messages.

• An actor is a role that a user plays with respect to the system. ActorName


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Use CaseUse Case

• A use-case is a set of sequences of actions a system performs that yield an observable result of value to a particular actor.

• A use-case describes a requirement for the system, that is, what it should do, but not how it should do it.

• A use-case is a set of scenarios tied together by a common user goal.

UseCaseName


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System boundarySystem boundary

• Represents the boundary between the (physical) system and the actors who interact with the (physical) system.


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Use Case DiagramUse Case Diagram

A diagram that shows the relationships among actors and use cases within a system.

Set Limits

Capture Deal

Price Deal

Analyze Risk

Value Deal

Update Accounting

Financial Trading System

Accounting System

Salesperson

Trading Manager

Trader

<<include>>

<<include>>


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Include (Uses) relationshipInclude (Uses) relationship

• Include : this relationship is used when there is a common chunk of behaviour across more than one use case.

• Primary use case includes the functionality of included use case.


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Use case relationshipsUse case relationships

Place Order

Supply CustomerData

Order Product Arrange Payment

Cash Payment Credit Payment

Request Catalog

<<include>> <<include>><<include>>

<<extend>>

These use cases are varieties of

Arrange Payment

generalization


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Generalization relationshipGeneralization relationship

• Generalization is used when there is one use case similar to another.

• Inheriting parent behaviour, adding and overriding with the child’s behaviour.

• Sub use case inherits behaviour and semantics from super use cases.


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Place Order

Supply CustomerData



Request Catalog


<<extend>>


Arrange Payment

generalization


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Place Order

Supply CustomerData



Request Catalog


<<extend>>


Arrange Payment

generalization

condition: {user request catalog}extension point: more requests

Place Order___________

more requests


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Extend relationshipExtend relationship

• Extend is used to add behaviour to the primary use case at certain extension points.

• A use case is optionally extended by functionality of another use case.


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D2D exampleD2D example

• D2D is a commercial online dating service• Requirements

– Interest– Subscribe

• Request for a subscription

• Cancel a subscription

– Profiles• Inspect a profile

• Modify a profile

– Messages– News


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D2D exampleD2D example

• D2D is a commercial online dating service• Requirements

– Interest– Subscribe

• Request for a subscription

• Cancel a subscription

– Profiles• Inspect a profile

• Modify a profile

– Messages– News

Request for subscription

Inspect profile

Modify profile

Cancel subscription

Visitor

Subscriber

D2D


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Primary use cases : examplesPrimary use cases : examples


Visitor

Inspect profile

Subscriber

Visitor

Modify profile

Subscriber


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Separation Separation

• If there are many requirements (also called processes in this

stadium); a requirement can be managed separately.

• In the case of D2D Profiles:– Inspect a profile

• Look for a profile

• Consult a profile

– Modify a profile


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Secondary use cases : an exampleSecondary use cases : an example

Use cases that supports the use case request for a subscription


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Secondary use cases : an exampleSecondary use cases : an example

Use cases that supports the use case request for a subscription– Import a subscription– Validate a subscription– Import credit card– Validate credit card– Mail confirmation by e-mail


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Secondary use cases : an example {uses include / extend relationships}

Secondary use cases : an example {uses include / extend relationships}


Inspect profile

Modify profile

Cancel subscription

Visitor

Subscriber

D2D

Visitor


Validate subscription

Import subscription

Import creditcard

Validate creditcard

Mail confirmation

<<include>>

<<include>>

<<include>>

<<include>>

<<extend>>


Inspect profile

Modify profile

Cancel subscription

Visitor

Subscriber

D2D


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Secondary use cases : an example {uses generalization relationships}

Secondary use cases : an example {uses generalization relationships}

D2D

Renew subscription

Pay subscription

<<include>>

Pay subscription with Creditcard

Pay subscription via Collection

Pay subscription via Account


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Use Case diagram – secondary actorUse Case diagram – secondary actor

Visitor


Validate subscription

Import subscription

Import creditcard

Validate creditcard

Mail confirmation

<<include>>

<<include>>

<<include>>

<<include>>

<<extend>>

Credit card company


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Use case descriptionUse case description

A use case can be described by a use case text, including the next characteristics:– Name: the name of the use case concisely– Actors: the involved actors– Precondition: condition of the system at the start of the use case– Stepwise description: interaction between system and actor(s)– Exception: exceptional cases– Result: post condition of the system


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Use case text example from Inspect a profileUse case text example from Inspect a profile

Visitor

Inspect profile

Inspect preferences

Look for profile

Inspect photo

Mail message

<<include>>

<<extend>>

Subscriber

<<extend>>

<<extend>>


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Use case text example from Inspect a profileUse case ‘mail a message’

Use case text example from Inspect a profileUse case ‘mail a message’

• Name mail a message• Actors subscriber, visitor• Precondition profile is known, actor is logged in• Description 1. get the profile

2. show web page

3. actor types in a new message

4. actor confirms mailing the message

5. application (d2d) sends message to profile

6. actor receives confirmation of sending a message

• Result message mailed to profile; or actor has canceled


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ScenarioScenario

A scenario is a sequence of steps describing an interaction between a user and a system.– A scenario is an instance of a use-case.– A scenario describes a possible interaction with the system.


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Scenario for use case ‘log in subscriber’Scenario for use case ‘log in subscriber’

Description1. Validate number of invalid logins .

2. If number of invalid logins more than 2, stop.

3. Show web page.

4. Actor types in login name and password.

5. Actor confirms.

6. Application validates login.

7. If login valid

7.1 mark actor as subscriber.

8. If login invalid

8.1 raise the number of invalid logins.

8.2 repeat from step 1.

Chosen scenarioNumber of valid logins < 3.

Show web page.

Actor types in login name and password.

Actor confirms.

Login is valid.

Mark actor as subscriber.


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Scenario example 1 of 2Scenario example 1 of 2

• Consider a Web-based on-line store, we might have a ‘Buy a Product’ scenario that would say this :– The customer browses the catalogue and

adds desired items to the shopping basket. – When the customer describes the shipping and credit card

information and confirms the sale. – The system checks the authorization on the credit card and

confirms he sale both immediately and with a follow-up mail.


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Scenario example 2 of 2Scenario example 2 of 2

Buy a ProductMain Success Scenario:

1. Customer browses through catalog and selects items to buy

2. Customer goes to check out

3. Customer fills in shipping information (address; next-day or 3-day delivery)

4. System presents full pricing information, including shipping

5. Customer fills in credit card information

6. System authorizes purchase

7. System confirms sale immediately

8. System sends confirming email to customer

Extensions:3a: Customer is regular customer

3a1: System displays current shipping, pricing, and billing information

3a2: Customer may accept or override those defaults, returns to MSS at step 6

6a: System fails to authorize credit purchase

6a1: Customer may re-enter credit card information or may cancel


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Template of use case textTemplate of use case text

Name Name used to refer to a use case.

Actors All actors involved.

Preconditions Condition of the system at the start of the use case.

Description A complete stepwise description of the interaction between system and actor(s).

Exceptions Special and/or unexpected exceptional cases.

Result Condition of the system at the end of the use case.


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NS Ticket machine – a use case approachNS Ticket machine – a use case approach

Traveler

Purchase Ticket

Maintenance basic data

NSTake ticket

Destination


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NS Ticket machine – use case diagramNS Ticket machine – use case diagram

<<extend>>

<<include>>

Pay ticket

Buy NS ticket

Buy OV ticket

Traveler


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NS Ticket machine – use case textNS Ticket machine – use case textUse Case Buy OV Ticket

Actors Traveller

Preconditions Traveller has a valid pass

Description 1. Ticket device expects destination code

2. Traveller enters destination code

3. Extension point: NS ticket

4. Ticket device checks code and calculates the charge. Shows destination code & fare. Activates ticket machine for paying

5. Traveller pays (use case: Pay ticket)

6. Ticket device print and supplies ticket

7. Traveller takes ticket

Extension Destination code = NS station.

3a. Ticket device expects ticket type

3b. Traveller enters Single/Return, Discount Y/N, Class

Exceptions Traveller interrupt the interaction or walk away

Traveller enters an incorrect destination code

Payment is not finished off successful

Result Traveller has ticket.

(NS can look forward to the payment)


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Activity diagramActivity diagram

Enter Destination

[else]

[ correct NS destination]

Choose single or return Choose reduction Y/N Choose 1st / 2snd class

[ bus&tram card]

Pay ticket

[ payment not OK]

Take ticket[ else]

Description can be modeled by an activity diagram

Make an activity diagram for the actor ‘Traveller’


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Study matterStudy matter

• Martin FowlerUML distilled , 2nd / 3rd edition – UML beknoptAddison Wesley

• Sander HoogendoornPragmatisch modelleren met UML 2.0Addison Wesley

• Grady Booch, James Rumbaugh, Ivar JacobsonThe Unified Modeling Language User Guide, 2nd editionAddison Wesley

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