Executable UML

The Models are the Code -Executable UML

Lecture 10 – Wrapping things up

Paul Krause

Executable UML

Subject Matter Partitioning

Sally Shlaer and Stephen Mellor established the foundations for this approach in 1988 Object-oriented Systems Analysis - Modelling the

World in Data

Recognises that a system consists of a set of subject matters - domains Each domain consists of a set of classes Domains are represented as packages in UML

A Domain Chart captures the dependencies between domains

Executable UML

What is a Domain? A domain is an autonomous, real, hypothetical

or abstract world inhabited by a set of conceptual entities that behave according to characteristic rules and policies Mellor and Balcer, p30

Real Worlds Air traffic control, patient administration, banking,

…

Hypothetical Worlds 3D geometry, statistical analysis, …

Abstract Worlds User interface, messaging, workflow, …

Executable UML

Example Domain Chart

Fuel Sales Shopping

ForecourtHardwareInterfacing

Checkout

User Interface LoggingTelecommunications

Interface

Executable UML

Advantages of Subject Matter Partitioning Reuse

Well-defined interfaces

Effective use of subject-matter knowledge

Stability to changing requirements

Stability to changing technology

Incorporation of third party software

Effective integration with Use-Case driven development

Executable UML

Use Case DescriptionUse Case Name

Purpose

Preconditions

Invariants

Primary Scenario

Postconditions

Make Fuel Delivery

To allow a paying customer to deliver fuel of a selected grade

The desired fuel grade is available

Tank level >4% tank capacity while pump is on

1. Customer removes nozzle from holster;

2. Attendant enables pump;

3. Customer selects one fuel grade;

4. Pump motor is started;

5. Customer uses trigger to control fuel delivery;

6. Customer replaces nozzle in holster;

7. Pump motor is stopped.

At least 2 litres of fuel have been delivered

Executable UML

Domain Level Sequence Diagram

<Boundary>Forecourt Hardware Interfacing User Interface Fuel Sales Checkout

1: binaryInputChanges

2: nozzleRemoved

3:requestPumpEnable

4:alertAttendantToRequestForPumpEnable

5:pumpEnableButtonPressed

6:pumpEnabled

7:GO creation

8:enablePump

9:setBinaryOutput

10:binaryInputChanges

11:triggerDepressed

12:startPumping13:impellorPulse

14:fuelUnitDelivered

1: Customer removes nozzle

2:

3:Request pump enable

4: Alert attendant of Customer

5: Attendant enables pump

6:

7: Create Transaction Item

8:

9: Pump motor enabled

10: Customer presses trigger

11:

12: Start pumping fuel

13: loop until trigger released

14: Unit of fuel is delivered

15: …

Executable UML

Domain Class Diagram - Fuel Sales

Pump

PumpSpecification FillingStation

Nozzle Tank

FuelGrade

Executable UML

Domain Class Diagram - Fuel Sales

Pump

PumpSpecification FillingStation

Nozzle Tank

FuelGrade

1 isDispensingFuelFor

1..* dispensesFuelAt

isSpecifiedBy 1

specifies 0..*

isInUseAt 0..1

hasInUse 0..1

1 isLocatedAt

1..* isLocationFor

suppliesFuelTo

0..*1

acquiresFuelFrom

1 currentlyStores

0..* isCurrentlyStoredIn

R4 R10

R6 R5

R1

R2

Executable UML

Domain Class Diagram - Fuel Sales

Pump

PumpSpecification FillingStation

Nozzle Tank

FuelGrade

1 isDispensingFuelFor

1..* dispensesFuelAt

isSpecifiedBy 1

specifies 0..*

isInUseAt 0..1

hasInUse 0..1

1 isLocatedAt

1..* isLocationFor

suppliesFuelTo

0..*1

acquiresFuelFrom

1 currentlyStores

0..* isCurrentlyStoredIn

R4 R10

R6 R5

R1

R2

Delivery

1 wasMadeFrom

0..* wasUsedToMake

Executable UML

Active vs Passive Classes

Active Classes The behaviour of instances of active classes

(“active objects”) varies over time e.g. Instances of a Thread class can be started,

paused, continued, stopped This behaviour can be captured in a Statechart

Passive Classes Passive objects have the same behaviour at all

times Operations on a class are sufficient to define its

behaviour Information classes, e.g. Address, are typically of

this kind

Executable UML

Modelling Operations Operations are used to model state-

independent behaviour

An operation is the invocation of some action via a parameterised interface think of a method call in Java or a function call in C

Operations are executed synchronously the caller waits until the action has been executed

and a result returned before continuing

The resulting action may in turn invoke (synchronously) other actions, or asynchronous behaviour by generating signals

Executable UML

UML Statecharts

Closed Down

Idle

Entry / displayWelcome

startup closedown

ProcessingCustomer

Input

card inserted / get pin

validation received [invalid card] / confiscate TerminatingTransaction

ProcessingTransaction

withdrawal selected [valid card] / display wait

Executable UML

Good Practice for Statecharts

Express the behaviour of Active Classes using a Statechart for each active class

Restrict usage to a subset of the full Statechart notation for clarity: Actions are specified on entry into a state (not

on exit, or on the transition itself) An individual event can only cause a single

transition out of a given state

This usage corresponds to expressing behaviour as a “Moore” machine

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Statechart for Delivery Class

Initialised

InProgress

fuelUnitDelivered()fuelUnitDelivered( )

Cancelled

Complete

deliveryComplete()

Executable UML

Statechart for Delivery Class

Initialised

InProgress

entry/ update volume delivered and cost

fuelUnitDelivered() fuelUnitDelivered( )

Cancelled

Complete

deliveryComplete()

Executable UML

Statechart for Delivery Class

Initialised

InProgress

entry/ update volume delivered and cost

fuelUnitDelivered() fuelUnitDelivered( )

Cancelled

Complete

deliveryComplete()

Action Language specifiesthe detailed action

that is performed herein terms of the concepts

in the associated domain model

Executable UML

Interactions within Domains

Operations can be invoked on objects or classes within a Domain.

Signals can be sent to (active) objects or classes within a domain.

Object-level sequence diagrams

Collaboration diagrams

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Interactions with other domains

Domain-level sequence diagrams

Operations can be invoked on other domains

Signals can be sent to other domains

Executable UML

Next Actions

Final Lab Class Tomorrow

Example Exam papers will put up on the Website tomorrow

If you have any further questions, please e-mail me or come along to office hours 2-4.00pm on Mondays