wk5 uml activity diagram

8/3/2019 Wk5 UML Activity Diagram

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7M822

UML Activity DiagramsUML Activity Diagrams

6 October 2008


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ExampleExample


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Activity Diagram: what is it?Activity Diagram: what is it?

Describes activities and flows of data or

decisions between activities

Provides a very broad view of business

processes

Can be used to break out the activities

that occur within a use case Good for showing parallel threads


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Activity Diagram: when to use it?Activity Diagram: when to use it?

When describing work flow across many use

cases

When analysing a use case, and before

methods are assigned to symbols

When dealing with multi-threaded applications


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Creating an Activity DiagramCreating an Activity Diagram

This diagram is useful in showing work flowconnections and describing behaviour that has a

lot of parallel processing.When you use an activity diagram you can choose

the order in which to do things.

It expresses the essential sequencing rules to

follow.It is different from a flow chart in that it shows

parallel processes, not just sequential processes.


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Activity DiagramActivity Diagram

Shows a set of activities, the flow from activity

to activity.

Represents the dynamic view of a system.

Models the function of a system.


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Activity DiagramActivity Diagram

Activity diagrams show the flow of control

between activities

They can model the sequential and concurrent

steps in a computational process

They can also model the flow of an object as it

moves from state to state at different points in the

activity


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UML Activity symbolsUML Activity symbols

ActionState initial state final state

Transition(Fork)

Transition(Join)

Control FlowDecision

Swimlane


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Action StateAction State

In a conceptual diagram an activity is a task that

needs to be done either by a human or a

computer In a specification-perspective diagram or an

implementation-diagram, an activity is a method

on a class


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Sequential BranchingSequential Branching

A sequential branch is represented as a diamond

It may have one incoming transition and two or more

outgoing transitions Guards are associated with each transition. The guards

are evaluated upon entering the branch, and the one

that evaluates to true is then taken


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ExampleExample


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Branch & MergeBranch & Merge

Calculate Risk

Issue a Loan

[ risk low]

Ask for Authorization

Continue

[ risk high]


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Forking and JoiningForking and Joining

Concurrent activities within an activity diagram are modelled

with the use of synchronised bars

Synchronisation bars are drawn as a thick horizontal or vertical

line

Joins and Forks should balance

The number of flows that leave a fork should equal to the number

of flows entering the corresponding join.


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Fork & JoinFork & Join

Issue a Loan

Reserve Money Make a Agreement

Make an Offer


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PrepareMeal

CookSpaghetti MakeSauce

Combine

OpenBottleWine

[ in the mood for wine]

Serve


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Forks, Joins & conditional ThreadsForks, Joins & conditional Threads

PrepareMeal

CookSpaghetti MakeSauce

Combine

OpenBottleWine

Serve

[ in the mood for wine]


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Swim lanesSwim lanes

The activities of an activity diagram may be performed by

different groups.

Each zone or lane represents the responsibilities of a particular

group.

If swimlanes are used, each activity can belong to one and only

one swimlane.

To use swimlanes, you must arrange your activity diagrams into

vertical zones separated by dashed lines.


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Swim lanesSwim lanes

AdministrationDeskFinance

Issue a Loan

Reserve Money Make a Agreement

Make an Offer


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Activity

Diagram

Activity

Diagram


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Composite ActivityComposite Activity


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Receive Order

Assign Goods to item

Authorize Payment

[ for each line item] /

Cancel Order

[ failed]

*

Reorder Goods

[ need to order]

[ succeeded]

Dispatch Order

[ stock assigned to all items and payment authorized]


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ExampleExample


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Object FlowObject Flow

Objects may be involved in the flow of control associated with an

activity.

These associations can be shown in activity diagrams by placing objects

in the diagram and linking them to specific activities using a dependencylink.

The same object may be the output of one action and the input of one or

more subsequent activities.

To distinguish the various appearances of the same object, the state of

the object at each point may be placed in brackets and appended to the

name of the object.


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Object

Flow

Example

Object

Flow

Example

StockroomSalesCustomer

Request service

Take order

Fill order

Deliver order

Pay

Take order

StockroomSalesCustomer

Request service

Take order

Fill order

Deliver order

Pay

Collect order

Order [placed]

Order [entered]

Order [filled]

Order [delivered]


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Date2date example: scenariosDate2date example: scenarios

Use caseLog in Subscriber

Step-by-step Plan1. Validate number of invalid logins

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

3. Show web-page4. Actor enters login and password

5. Actor confirms login

6. Application validates login

7. If login is valid

7.1 Actor is marked as subscriber

7.2 Stop

8. If login is invalid8.1 Increase the number of steps

8.2 Repeat from 1.


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Use Case Log in subscriber

Actors Subscriber, Visitor

Description

Pre-conditions

Check validity actor as subsciriber

----

Basic flow 1. Validate number of invalid logins

2. Show web-page

3. Actor enters login and password

4. Actor confirms login

5. Application validates login

6. Actor is marked as subscriber

Extension /

Exception flow 1a Login is invalid

1a1 Number of logins >2, stop

5a Login is invalid

5a1 Increase number of logins, repeat 1

Post-conditions Actor is known as subscriber and actor is logged in

Date2date : Log in Subscriber use case textDate2date : Log in Subscriber use case text


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Date2date :

Log in

subscriber activity diagram

Date2date :

Log in

subscriber activity diagram


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Key pointKey point

Activity diagrams are useful for

Business Process Redesign

Work Flow Modelling

Analysing Use Cases


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NS Ticket serviceNS Ticket service

Define a use case diagram of

NS Ticket service

Describe an use case.

Take ticket

Destination

Single / Retour

No Reduction /

40% reduction

2e class / 1e class


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Use Case diagram NS Ticket serviceUse Case diagram NS Ticket service

Traveller

Buy OV ticket

Buy NS ticket

Pay ticket

extends

uses


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Use 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. Showsdestination 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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Make a class diagram of NS ticket service

including the classes Ticket and

Destination

Make a class diagram of NS ticket service

including the classes Ticket and

Destination

+create()

+payPrice()

+printTicket()

-fromStation-toStation

-oneWay : Boolean

-reduction : Boolean

-class

-date : Date

-price : Currency

Ticket

+validateDestination()

+showPrice()

-code

-name

-distance

-base price

Destination

+Print()

+checkStatusPrinter()

-statusPrinter

Printer

* 1


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Make an activity diagram for the actor TravellerMake an activity diagram for the actor Traveller

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]

wk5 uml activity diagram

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