Last lectureState Machine Diagrams

Use Case Diagrams

Specification and Documentation Techniques:Graphical Notations (3)

CS/SE 3RA3

Ryszard Janicki

Department of Computing and Software, McMaster University, Hamilton,Ontario, Canada

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Last lectureState Machine Diagrams

Use Case Diagrams

Context diagrams - chemical tracking system

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Dataflow diagrams: chemical tracking system

Last lectureState Machine Diagrams

Use Case Diagrams

From context diagrams to dataflow diagrams: ChemicalTracking System

Ryszard Janicki Graphical Notations (3) 4/18

Last lectureState Machine Diagrams

Use Case Diagrams

Finite state machines, transition systems, finite automata

Capture the admissible behaviors of system components

Behavior of component instance = sequence of statetransitions for the items it controls

State Machine State = set of situations where a variablecharacterizing a controlled item has always the same value

- e.g. state MeetingScheduled : always same value for Date,Location (while other variable WithWhom on Meeting maychange value)

- Initial, final states = states where item appears, disappears- States may have some duration

State transition: caused by associated event

- if item in source state and event ev occurs then it gets totarget state

- Events are instantaneous phenomena

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UML type notation: Hotel reservation

Notation:

Example: Hotel reservation

State Machine Diagram: Meeting scheduler

Example of state machine diagram:meeting controlled by a meeting schedulerg y g

[Unauthorized] RequestDenied

initial state final state

meetingRequest Gathering

MeetingData KO-request

ValidatingMeeting

Data

[Authorized]

OK-request

ConstraintsRequested

Planning[All available]

statetransition

[Noconflicts]

Requested[Conflicts]weakening

Requestschedule

Determination

state

event

notification

Resolving MeetingScheduledstate

guardMeetingNotified

g

Last lectureState Machine Diagrams

Use Case Diagrams

State Machine Diagram: Road treatment (deicing)

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State Machine Diagram: Home security system (part of)

Chemical request in the Chemical Tracking System

Dataflows and state machine diagrams

Flows are modeled by state machines

Last lectureState Machine Diagrams

Use Case Diagrams

Example (Elevator: A person using an elevator)

Q6[5+5=10]

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Last lectureState Machine Diagrams

Use Case Diagrams

Example (Elevator: A car of an elevator)

Q6[5+5=10]

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Last lectureState Machine Diagrams

Use Case Diagrams

System operations: use case Diagrams

Capture operations to be performed by a system componentand interactions with other components

- yet simpler, outline view ... but vague- to be made precise by annotations, interaction scenarios, etc.- introduced in UML to replace dataflow diagrams

Structuring mechanisms:

- <<include>>: to specify “suboperation”- <<extend>> + precondition: to specify “variant” operation

in exception case

Ryszard Janicki Graphical Notations (3) 14/18

Use case diagrams: scheduler

Use case diagram: example

operation interactionenvironment component

Check Request

Initiator <<extend>>Unauthorized

AskConstraints

CollectConstraints

ParticipantUnauthorized

Deny Requestvariant

operation

DetermineSchedule

C fli t<<include>>

MergeConstraints

R l

software component

Scheduler

ConflictResolver

ResolveConflictsParticipant

suboperation

operation performer

Use case diagrams: chemical tracking system

Use case diagrams: roads deicing

Example (Elevator: Use Case)

Q5[10]

Marking Scheme：

1) At least three types of user should be covered and well-described.

or

2) If you included Passenger/User and Site Manager/ Operator only, AND you

provided a very good use case diagram, also could be full-mark.

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